texts: What are the differences between the SR 71 variants?

texts: I read that all SR 71 blackbirds were different, what was different with each one and is one regarded as superior to the rest? Why?


texts: Is an F-16 able to fire any of its weapons while on the ground?

texts:
I can recall at least one Hollywood movie, where this takes place (although not an F-16 in the movie).

Is this at all possible? Can the F-16 fire its M61 while taxiing on the ground? What about other weapons?

Note that I'm not even sure myself what good this would do or what the point would be. I'm just curious.

I can imagine the bullets would not even be able to hit a target on the ground, perhaps pass over or below the target. Does the M61 even point perfectly parallel to the ground on an F-16? At least it would change its elevation by some degrees up and down when taxiing, braking, etc. I suppose I could imagine helmet cuing of a low-flying target with an AMRAAM while the aircraft is still trying to take off. Since it has happened before that an airbase is taken by surprise, perhaps this question is not as silly as I at first thought. However, I'm under no illusion that an AMRAAM would be able to engage any target when fired from an aircraft on the ground---doesn't the missile need some time and space to drop from the rail and fire its engine?

I'd love to be told that I'm wrong though.

Nevertheless, I'm curious if the aircraft is designed to prevent firing its weapons while the landing gear is out, or a similar safety feature. If so, can it be overridden? Specifically, what, if anything, prevents an F-16 from firing its M61 while on the ground?

As a bonus question, has this by accident ever occurred, that an aircraft (F-16, or other) fired its weapons while stationary, or taxiing around at an airport?


texts:
I have known that when you climb, you push the throttle to maximum and adjust the vertical speed with the commands (elevator) and the trim. Then when you reach the desired altitude you pull the throttle to cruise RPM setting (2350 for example) and it will maintain level.

For descents you pull the throttle to decrease RPM and you adjust your vertical speed with the commands and the trim again. Then when you reach the desired altitude you push the throttle to cruise RPM setting again and it will maintain level.

Obviously, using the carb heat (hot when lowering down the RPM and cold when increasing).

Is this correct? Is there a better way to perform this maneuvers?
Thanks, and sorry for the noob question.


texts: Are turbine engine reconditioned after severe FOD damage caused by bird strikes?

texts:
I've just been watching a video of a 757 suffering a bird strike on take off. The pilots continue with their take off, declare a MAYDAY, shut the engine down and proceed to land without any issues.

Link to the video: https://www.youtube.com/watch?v=9KhZwsYtNDE

Are these engine reused after an event like this? Are they sent away to Rolls Royce, Pratt & Whitney etc to be repaired? Or are they always deemed a complete write off and replaced with new?

Obviously turbine engines are highly balanced complex pieces of machinery so I can imagine once FOD has damaged this balancing the damage is pretty high.


texts: If I'm instrument current in an ASEL, am I also considered current in an AMEL?

texts:
FAR §61.57(c)(1):

Within the 6 calendar months preceding . . . logged at least the
following tasks and iterations in an airplane, powered-lift,
helicopter, or airship, as appropriate . . .

I would infer from this that 1) instrument currency does NOT carry over from one category to another but 2) that it does carry over from one class to another within a category. Is that accurate?


texts: Why should isobars be aligned with the leading edge of the main wing for a transonic cruiser?

texts: When designing an airplane meant to cruise at transonic speeds (or supersonic speeds), I heard that one should look at the isobars on the main wing in order to assess if the shape, sweep angle and other airfoil parameters are suitably chosen. I also read that the better configuration yields isobars that are parallel to the leading edge. I already know that there are several techniques to get the isobars aligned with the leading edge (area ruling, adapting the sweep angle, extra care in the design of the junction between the fuselage and the wing), but why is this configuration better than another one? What does it improve?


texts: What is maximum displacement for aircraft engine?

texts: Is there any standards or at least typical values of aircraft engine displacement and rotation relatively to the wing in flight? Actually I'm looking for that values at Boeing 747-400 RF or ERF.


texts: How long is maximum time to investigate an airplane crash?

texts:
Lion Air flight 610 was crashed on 29 October 2018. It was Boeing 373 Max 8. Almost one year ago. I have not heard any news from National Transportation Safety Committee (NTSC) when they will release the investigation report to media.

From the previous accident, AirAsia QZ8501 occurred on 28 December 2014 with Airbus A320 airplane, NTSC took less than a year time to release the investigation report to media. On 4 December 2015, the NTSC did the release the report.

Then my question is, how long is maximum time to investigate an airplane crash?


texts: What is this vintage small airplane with low wings and twin propeller engines?

texts: Could anyone help me to identify this vintage aircraft, that can be seen in the background of this photograph, please?


texts: Do you need to fill out the MedXPress form every time you renew your medical?

texts: In the US, to get a 3rd-class medical certificate I know that you have to fill out this form on the FAA's website, get a confirmation number, then take that confirmation number to the medical examiner. My question is, do I have to do that every time? Or is the one confirmation number good forever?


texts: Is an EASA flight school required to give me my training records if I leave?

texts:
I am having troubles with my flight school in Austria/Europe. So I want to change school but the school won't give me my training records so I can't finish my training somewhere else.

Is there any EASA regulation that states they have to return my records?


texts: Is it allowed to start engines during push-back?

texts: Is it allowed, considered safe, and done, to start the engines while the aircraft is moving under the push-back power? On one hand it seems like a big time saving, on the other hand the running engines are rather dangerous and there is still a wing-walker often present during the push back.


texts: Why does this plane not pitch up after a dive?

texts:
I've tested my RC plane yesterday. It's a canard. After hand launching, the plane goes straight, then I change the elevator to go down and it's going down, but when I pitch up the canard doesn't work and the plane crashes.

The plane is at full throttle.
When diving the plane slightly rotates to right.
Controls tested before flight.

Edit:

Airfoil is a NACA 2412, but tips gets a little thick (all cutting, sanding is done by hand)
No incidences.
One servo for the canard and one servo for the ailerons.
No thrust angle.

The plane:

CG is just in front of the vertical stabilizer (the little cross in the image)


texts: What certifications must one have to repair/alter propellers and instruments?

texts:
According to 14 CFR 65 Subpart D

  A certificated mechanic may perform or supervise the maintenance, preventive maintenance or alteration of an aircraft or appliance, or a part thereof, for which he is rated (but excluding major repairs to, and major alterations of, propellers, and any repair to, or alteration of, instruments), and may perform additional duties in accordance with §§65.85, 65.87, and 65.95.

(Emphasis mine)

What certifications are necessary to affect the repairs or alterations specifically excluded from a "mechanic" certificate?


texts: Why hang glider dont over pitch when inrease AoA?

texts:
Glider change AoA with changing c.g.
To do that,you must push control bar forward,your c.g. move back,so we have torque in clockwise direction which wants rotate glider..
Situation can be even worse,because increased AoA shift center of pressure(lift) more forward.
Why glider dont over pitch(and stall),what stop this dangerous torque when you must fly with higer AoA?What gives glider restoring torque if he dont has tail?


texts: What happened to this airplane at Lombok Airport?

texts:
Last month I was in Indonesia and I had to take a flight from Lombok International Airport (IATA: LOP). While I was waiting for boarding I noticed an airplane (wreck) next to the runway that was somewhat burned down at the front (fire?).

The abandoned plane at Lombok International Airport. (personal photo)
I was intrigued by the way that it was just placed there, so close to the runway. I thought about an accident where this aircraft was involved in, could've have just happened a couple of days or weeks before. But I couldn't find any source in collaboration with this particular airport. I maybe thought that the airplane was used to train fire fighters, as I see that more often on other airports in the world. I tried to find more info about it on the web, but no luck.

The airplane on the map
I also headed out to Google Maps, Bing Maps and Apple Maps to see if the plane was there.
Google Maps has the airplane on its map (see image below, top middle and slightly to the left), the data is from 2016, so says the footer.
Google Maps location of airplane on Lombok International Airport, data consulted on 2 Dec 2016.

Bing Maps isn't having the airplane on its map, but maybe that's because the map is outdated (?).
Bing Maps location of Lombok International Airport, data consulted on 2 Dec 2016.

Apple Maps shows an airplane in almost the same spot (it's just on the concrete I think), but is it the airplane?
Apple Maps location of 'airplane' on Lombok International Airport, data consulted on 2 Dec 2016.

Zoomed pictures of the plane
The above picture is zoomed in on in the following pictures. Unfortunately, the aircraft registration is not visible.

And now?
I'm eager to know what happened to this plane. What type is it? Who is the owner? Can anyone tell me? Thanks in advance.


texts: What are aerodynamical reasons behind slight dihedral or no dihedral at all?

texts:
Regarding general aviation single engine high wing aircrafts in particular, what are the reasons for some of them to have no dihedral at all on their wing, or slight positive dihedral angle for other?

For instance, why do Piper J-3 Cub and Fiesler Fi 156 Storch both have no dihedral at all, when Zenair CH 701 and Cessna 172 display some slight positive dihedral?

And why aren't there any GA aircraft, high wing single engine, with slightly negative dihedral, like it is often seen with fighter aircrafts, such as F-104 (mid wing) or Harrier (high wing)?

Even if these examples were designed at different times, they all have wings with struts, so the reason cannot be structural, like at the time one straight wooden spar would have been more convenient.

(Piper j-3 Cub could be in the double-dihedral wing category, since its wingtips display dihedral, yet it is mainly one flat wing.)


texts: Must I log aircraft checkout flights as dual received?

texts:
14 CFR 61.51 says:

  (h) Logging training time.
  (1) A person may log training time when that person receives training from an authorized instructor in an aircraft, flight simulator, or flight training device.
  (2) The training time must be logged in a logbook and must:
    (i) Be endorsed in a legible manner by the authorized instructor; and
    (ii) Include a description of the training given, the length of the training lesson, and the authorized instructor's signature, certificate number, and certificate expiration date.

If I am rated in the aircraft and just getting a local FBOs checkout or familiarization flight with their instructor, must I (also) log it as dual received? Yes I see the word "may" in (h)(1)


texts: What is the definining line between a helicopter and a drone a person can ride in?

texts:
When I say drone in this context I don't mean an unmanned aircraft. I'm not sure what the terminology of a drone that has been adapted to carry a person? Is this picture below considered a helicopter or what? What if it ran on petroleum?

If not, then how is the separation between a VTOL aircraft and helicopter defined?

Would a Chinook that can fly itself be a drone?


texts: What does the term "white-scarf Air Force" mean?

texts:
Ron Gordon's answer to question about A-10 cannon mentions "white-scarf Air Force". As civilian, subtlety was lost on me. What does it mean? From the context, looks like fighter pilots? Are the scarves of other colors, and what they are?

In particular:

  "The white-scarf Air Force has an averse to building flying tanks and particularly doesn't like single-mission, CAS systems. They never will forget that the A-10 was forced on them."


texts: What's the difference between a "flight line" and a "tarmac"?

texts:
I was at a conference where there was a discussion on ontology for assets.  There were two classification trees, one for assets on the flight line and one for assets on the tarmac.

What is the nuance between these?  Is it active aircraft vs. inactive aircraft?


texts: What advantages are provided by an unstable canard configuration for fighters?

texts:
Why are most canard fighter aircraft unstable?  A stable design would let the canard provide lift.  My guesses are:

Increase pitch rate
Decrease stability while supersonic (supersonic, the aircraft are stable)


texts: How common is it in current British usage for the angle between the chord line of a wing and the flight path to be called the "angle of incidence"?

texts:
In American usage, the angle between the chord line of a wing and the flight path is called the "angle of attack".  The angle of attack is also represented by the greek letter "alpha".  However, some British authors, especially in the past, have referred to this angle as the "angle of incidence".  (See one supporting reference here.)

We'll call this the "older British" use of the term "angle of incidence".  How common is this usage now in the British aviation world?  Has it completely fallen by the wayside, or is still common?  Was it ever very common?

Also, what term or terms did authors and speakers following this "older British" usage, use to refer to the angle between the wing chord and the longitudinal axis of the fuselage (or some other similar defined datum line approximating the longitudinal axis of the fuselage?)  Some of the terms that have been used for this angle by writers and speakers following the "older British" usage noted above, appear to include "rigger's angle" and "rigger's angle of incidence".  Are there others?

(In American usage, this latter angle is in fact the angle that is called the "angle of incidence".)

(Bonus extra part: is there one particular greek letter that is normally assigned to this latter angle in engineering texts and papers, much as "alpha" is normally assigned to the angle that is described in the first paragraph of this question?)


texts: Does the minimum power required for level flight depend on CD0?

texts:
I came across this video few days back on Edx 16.101 youtube channel.

At 7.00 min of the video, the presenter derived an equation for minimum flight power which does not depend on Cd0.

$$P_\min = \frac{4}{3\pi e AR}  \sqrt{\frac{2W^3CL}{\rho S}}$$

I don't have a doubt on the derivation, but this result seems to be very contradictory for me.

For example, let's take 2 identical aircrafts, one with fuselage airbrakes deployed and one without. (Identical CL, AR, $\rho$, S, CL and e but different Cd0)
According to this expression the power requered cannot change. But,

For same CL, V is going to be the same
With airbrakes deployed, aircraft 1 drag is much higher than the aircraft 2
Power required (D*V) should be higher for aircraft 1.

May be I am missing something simple. Why is this apparent contradiction?


texts: How much pressure does the compressor of an engine of B787 exert on air?

texts: I have been intrigued by this new airliner, especially about the engine. Can anyone tell me how much pressure is the compressor given by the Boeing 787 and how it can be calculated?


texts: Is it possible to reload Electric Aircraft in mid-air from a tanker aircraft?

texts:
Can this be done military style refueling but with an electric wire boom supplying current from tanker aircraft to electric aircraft mid air in flight? Electricity from the tanker craft can be generated from its engines and/or an on board diesel generator. And utilising fast charging technology for quicker refuel times to recharge the electric aircraft's batteries.

Is a technology demonstrator already available? Or is Google not showing me any results?


texts: What is the "optimal" age of a fighter pilot?

texts:
Fighter pilots are always portrayed as young, fit men (and woman), in their 20s and 30s - and most of the F16 pilots I know are that age.

However, today someone, who is over 50 years old, mentioned that he was asked to be an F22 pilot.  His background is astonishing, flying in multiple "wars," and he was even the commander of the Thunderbirds in F-16s for a while.

Even though this man clearly has the background of the stereotypical F22 pilot, would age be a problem?  Wouldn't someone whose body could take more abuse be better suited for that type of assignment?


texts: For how long can an Embraer E195 airplane glide at malfunction?

texts:
E195 specs:

Maximum Takeoff Weight 52,290 kg
Max Cruise Speed M 0.82
Cruise altitude: 35000 feet

Assume the weather condition is perfect (no clouds or gust winds). Also assume this airplane is fully loaded and just reached cruising altitude at its max speed. There and then, both jet motors immediately stops due to malfunction. No fire or anything, they just stop.

Given this scenario; will this aircraft be able to "glide" downwards for an emergency landing, or will it just drop dead and head for the earth? If it won't glide, how long will it take until it reaches the ground for impact?

(Reason for asking: me, being horribly scared of flying, just took a trip with this exact plane model, and I could not get the above thoughts out of my mind)


texts: Was the foil in older FDRs reused when it ran out, or replaced?

texts: Before magnetic tape became the standard recording medium for flight data recorders, most FDRs used a long strip of metal foil that had altitude, airspeed, etc. traces scratched into it by a set of styli inside the FDR (although a few very early FDRs used wire recording instead).  Judging from a number of NTSB accident reports that mention FDRs where the foil had run out and been taped down at the end for maintenance, this presumably wasn’t a continuous loop of foil (although I can’t imagine it would have been hard to implement a continuous-loop system; it seems to me that, to make such a system workable, all you would have had to do would have been to squeeze the foil through a set of metal lips to flatten out the old traces just prior to passing under the sticks), but, instead, one that had to be removed and dealt with by maintenance when it ran out.  When a foil FDR became full and was removed for maintenance, were the traces flattened out of the foil and the foil reused, or was the strip of foil replaced with a new, empty strip (with the full strip presumably being either discarded or possibly stored in an archive somewhere)?


texts: Can an airfoil have multiple aerodynamic centers?

texts: Aerodynamic center is a point where the moment is independent of angle of attack. Can we have 2 or more such points? Does it necessarily lie inside the airfoil?


texts: How to determine climb performance for various flight speeds?

texts:
I have the following climb performance chart:

and I need to evaluate the maximum rate of climb in different flight conditions.
The problem is, this chart is valid only for 85KIAS. Is there a way to evaluate the maximum rate of climb for other flight speeds, given the RoC and climb gradient @ 85KIAS?
edit: The zero-lift drag coefficient and aspect ratio of the aircraft are given. And it is not important if it is an optimum climb or not, I simply need to predict the maximum achievable rate of climb, given flight speed, altitude and aircraft mass.


texts: How would an aircraft fly PIKES ONE departure procedure of Denver Airport?

texts:
I was examining FAA's departure procedures and I noticed PIKES ONE SID (chart and continuation) which serves Denver Airport.

In the description, it states:

  TAKEOFF ALL RUNWAYS: Fly assigned heading for RADAR vectors to assigned route. Climb and maintain 10000 or ATC assigned lower altitude. Expect filed altitude 10 minutes after departure.

  LOST COMMUNICATION: If no transmissions are received within one minute after departure, maintain assigned heading until 7000 feet, then climb to filed altitude via direct DEN VOR/DME, thence via assigned transition.  If filed altitude is above 10000 feet, cross DEN VOR/DME at or above 11000 feet.

What troubles me is that DEN navaid is (obviously) very close to the airport, so I am not sure how an aircraft would depart from the airport via a runway very close to DEN, for example 07/25, and have enough space in order to reach DEN. In addition, based on Lost Communication, an aircraft would climb until 7,000 feet and then go direct to DEN, even if it has already surpassed DEN (by departing, for example, via runway 17R/35L) and theoretically it can just follow the assigned route by skipping this navaid.

In other words, is the aircraft obliged to fly to DEN before following the assigned route under any circumstances and, if yes, what would be a possible flight path in case of a runway that is really close to it?


texts: How much is a swashplate system more energy efficient than a fixed blade system for the same load

texts:
When reading about the lifting capacity of swashplates (as found in helicopters) vs fixed blade systems (as found in e.g. DJI drones), I read a lot of comments about the fact that the bigger rotors of a helicopter are more efficient. But how does that link to the system (fixed vs swashplate) and how much efficiency are we talking about? Now, I know that the question is way too simple for the complexity of the problem, also after reading these questions 1, 2, 3
The factors that influence this problem is also part of the 'quest' and I hope to reach a ballpark figure. It also links to the complexity of the use of a swashplate or even a virtual one. A very complex system can be more efficient in the long run, but is it worth it. That is the underlying question.
If possible could you explain formula's? I had math and physics back in the day until the age of 18 (VWO for the dutchies), so it is rather rusty.
edit: the core of the question is the system efficiency vs 1 or multirotor


texts:
I know on the 737, the leading edge slats deploy at the first flap setting, and the trailing edge flaps deploy after that at higher flaps settings. Why do the slats deploy before the trailing edge flaps?

LE Flap and slat schedule as it relates to TE Flap position for the 737-300:


texts: Why would a C150 tachometer bounce so much that the needle fell off?

texts:
On a long flight in a C150E, the tachometer started bouncing a little bit and the severity of the bouncing gradually increased until it was extreme: The tachometer was spinning in loops and making a loud screeching sound.
 The counter continues to increment.

Here's a video of the tachometer in the last 10min of our flight. Just after that video, the needle fell off, but the screeching sound persists and the metal pin at the center still seems to be spinning:

What could cause this?

I understand the tach needle is not powered by any gear mechanism, but rather a small alternator that converts the angular velocity of the tachometer cable into a current which exerts a force on the needle.  This should be highly reliable and I don't see how it could cause this behavior.


texts: How do you perform a gear-up landing in a large airliner?

texts: How do you perform a gear-up landing in a large airliner (say, a Boeing 747)?  Would you fly it like a normal landing, or are there special considerations (angle of touchdown, use/non-use of thrust reversers, etc.)?


texts: Are there any fly-by-wire airliners with negative or near-neutral pitch stability?

texts:
Are any modern commercial airliners with fly-by-wire flight control systems designed with negative or near-neutral pitch stability so that they can take advantage of the capability of such systems to reduce trim drag and increase fuel efficiency?

If so, which aircraft are so designed?

And if not, why not?

In the images, the aircraft with positive static stability must produce sufficient wing Lift (the green arrow), not only to hold the aircraft up, but an additional amount to compensate for the lift from the tail surface, which is pulling the aircraft towards the dirt. The total aerodynamic force is the sum of the Wing Lift plus the tail plane lift, which must equal the weight of the aircraft plus twice the lift produced by the tail. THIS MEANS THAT IN AN AIRCRAFT WITH POSITIVE STATIC STABILITY, THERE IS SIGNIFICANTLY MORE TRIM DRAG AND THRUST REQUIRED.

In an aircraft designed with negative static stability, (bottom image) The wings, (Green arrow) plus the tail plane, (blue) both contribute to positive (upwards) lift, and so the total aerodynamic force is less, therefore the induced drag is less, and the thrust required (and fuel flow to generate that thrust) is reduced in comparison to an aircraft with positive static stability..
if you would like more details, review this video, from which I quote (at about the 1:00 minute mark), speaking about general aviation aircraft with positive static stability,  "... Something not very pretty about this situation, [positive static stability], is that we have this downwards acting lift force[ at the tail], which we call Trim Drag, which essentially, in a negative way, impacts our range and endurance, and which we'd like to avoid...", and then later, talking about the negatively stable F-16, at 1:50 minute mark, "In this situation we have, [at the tail], an upwards facing Lift force. This means ... we have, as it should be, all the lift facing UP. This means [my italics], we have an increase in our range and endurance performance.."

And, in addition, from this link, I quote "unstable designs get a slight reduction in drag and a slight increase in lift".  The rest of this article is also very informative.

To further illustrate the difference, below are two photos, of aircraft on final approach to land, where the flight path is stable and descending.
1. An F-4, with positive static stability, and 2. an F-16, which has negative static stability. Note the relative positions of the stabilators on the two aircraft, and especially, the relative angle of attack of the stabilators as compared with the AOA of the wings. In both of these pictures the aircraft is descending to land, so the relative wind is from the left, and below.


texts: Were any composites used on the A340 series?

texts: Were any composites used in the construction of the A340? If so, which ones?


texts: What does 3Q8 mean in the aircraft model Boeing 767-3Q8?

texts:
I have aircraft types like Boeing 767-3Q8, Boeing 767-33A, Boeing 767-3P6ER and many others. I know what ER means. But what is coded as 3Q, 33A, 3P6 etc.?

How can I convert it back to more common types like Boeing 767-300? Just replace last two symbols with 00?


texts: Why would there be a NOTAM for an airport rotating beacon being on continuously?

texts:
This NOTAM currently exists at Riverside airport:

!RVS 01/014 RVS AD AP ABN ON CONS 2001141700-2001291700

The rotating beacon is on continuously per this NOTAM.  It has nothing to do with the weather.

Why would an airport do this other than in IFR conditions during the daytime?


texts: Are pilots generally trained for crosswind landings?

texts:
A YouTube footage of a KLM Boeing 777 landing at Schiphol airport in the Netherlands is certainly scary as the plane bumps and weaves and rolls from side to side.

Are pilots generally trained to handle such eventualities (or are such landings common in certain regions of the world?) or was everyone involved including the pilot taking a risk in this case without diverting the aircraft to a nearby safe location?


texts: What safety mechanisms prevent thrust reverser deployment in mid-flight?

texts:
I just came across the Wiki article on Lauda Air Flight 004, which was destroyed when a thrust reverser activated in mid-air.

In the article, it says:

  The incident led Boeing to modify the thrust reverser system to prevent similar occurrences by adding sync-locks, which prevent the thrust reversers from deploying when the main landing gear truck tilt angle is not at the ground position.

But that can't possibly be enough. Landing gear is lowered and locked while the plane is still flying. That means these "sync-locks" would be released while the plane is still in the air.

Edit: Looks like I misunderstood what "not at the ground position" meant. Apparently the truck tilt angle is not flush except when the wheels have pressed onto the ground. Nevertheless, the general question of what safety mechs there are, still stands.

Are there any other safety mechanisms? Are there any that detect, somehow, that the wheels have actually touched down? Maybe a wheel RPM sensor?


texts: Why do high-speed water impacts / ditching usually result in structural loss of the airframe?

texts: Plywood sheets can penetrate tree trunks unscathed - when pushed by hurricane or tornado winds.  Why wouldn't an airplane fuselage, wings and tail behave the same way impacting ocean water at a steep angle at 300-500 mph?  That is, penetrate and remain intact. I have seen a lot of supposition written about this which seems based on common sense, but common sense might be misleading.  Has  the outcome of such an event ever been demonstrated?


texts: What keeps Russian airliners from being as fuel efficient as their Western counterparts?

texts: Peter Kampf points out in his answer on IDing Tupolevs that the Russian transport aircraft designs tend to be quite aerodynamically refined, in some ways better than their Western counterparts on that front.  What kept them from matching the West when it came to fuel efficiency then?  Was it purely a matter of the Russian need to build sturdy aircraft to withstand their rough strips in the middle of Siberia?  Or were there other factors, such as engine technology, in play?  And have the Russians "caught up to us" regarding aircraft fuel economy, or are they still trying to get the hang of building fuel-sipping airplanes?


texts: What is the name for a flight crew that includes extra members for a longer flight?

texts:
For short haul flights, airlines fly with BASIC CREW.
For long haul flights, the crew must be composed for another crew or "extra" crew members, less than a crew.

What's the designation of the crew, that comprises more than the minimum number required to operate the aeroplane?
For example: 2 captains and 2 FOs; 1 relief pilot; 2 captains and 1 FO.


texts: Why does Jet A currently cost roughly the same as 100LL?

texts:
I thought Jet A was substantially cheaper than 100LL but I recently looked at the prices throughout my area, and they are both priced at approximately $5.50 per gallon. I've never flown an aircraft that uses Jet A so I've never really paid attention, but I could have sworn that it was much cheaper than the leaded 100LL.

I can't find any articles or information online as to why Jet A is as expensive as 100LL. Avgas or 100LL is a specialty fuel and the only leaded fuel that is still made, so that explains why it is expensive, but Jet A is ubiquitous and produced in large quantity.

This previous question suggests the same thing that I'm saying, that Jet-A is cheaper because 100LL is a specialty fuel produced in small quantity, and Jet-A is widely available, etc. So, what has changed in the last 2 years?  It can't just be supply and demand.


texts: Has anyone considered filling aircraft voids with helium to reduce the risk of fire?

texts:
Watching air crash investigations, and aware of problems with batteries, the issue of fire and sparking is recurrent. As a noble gas, pure helium would not burn, and if I understand correctly would reduce though not necessarily eliminate sparks.
While any additional lift would be marginal, it would likely be sufficient to compensate for the materials necessary to ensure a sufficiently sealed envelope.

So... Has anyone considered filling aircraft voids with helium?


texts: How is risk managed in single engined piston aircraft flights?

texts:
I have already read this post:  How dangerous is flying in a single-engine plane?

Recently as reported in the NTSB accident database, a pilot of a light aircraft encountered engine failure after take off. The pilot found no suitable area for performing and emergecny landing and deployed the aircraft parachute, escaping with some injuries.

It appears that some phases of flight of a piston single, there are sections of the flight for which safe recovery from an engine failure is not possible due to the lack of reachable emergency landing areas.

For example, after take off, the aircraft may be in a position that a safe landing and stop cannot be made with remaining runway. After take off, the pilot may encounter a heavily wooded or built up area, but a few minutes later may cross a highway or an empty field. In any case, his chances for safe landing keep changing throughout the flight, going from high to low to medium and so on.

Is it correct to say that this risk has to be taken, cannot be avoided?
Is it possible to reduce this risk with either better pre-flight checks and through purely technological means? Suppose I am taking flight instruction can I do anything to reduce the risk of engine failure?


texts: Can a paraglider rescue chute and its pilot handle terminal velocity?

texts:
Imagine a paraglider cuts his main chute and reaches terminal velocity. Can he still land safely when he deploys hes rescue chute?

The european standards require that paragliding rescue chutes can handle opening shocks as high as 60 m/s at full load. Google tells me that termial velocity is around 53 m/s for a human skydiver. Is that requirement enough to safely say it can handle terminal velocity? Note that a paraglider can have equipment up to 15kg. Is it possible one could hurt himself when opening paraglider rescue chute because they can open to fast?

European Standard EN12491

EDIT: I've found this post where somebody talks about how he deployed a hangglider reserve while he was falling at terminal velocity. He talks about how he survived and how he has seen another similar case where it went the other way.


texts: Why are the 737 trim wheels located so close to the seats?

texts:
I recently had the opportunity to try a 737 simulator and one thing that struck me was the placement of the trim wheels. They are located dangerously close to the seats and, man, do they spin fast. I can only imagine the pain if you accidentally leave the manual trimming handle retracted or if you get some hair stuck in there.

Why are they placed this way? I would assume that a less prominent placement would still allow easy access for manual trimming.


texts: What are the reasons for using hydraulic power on major aircraft systems?

texts: What are the actual benefits or advantages of using Hydraulic energy in aircraft systems, compared to pneumatic and electrical systems.


texts:
Today in Ground School we learned about radio navigation. I read here that the rotating part of the VOR rotates at 1,800 RPM (wow! Is it an electric motor that spins it?)

We know that modern Active Electronically Scanned Array radars are able to send signals in different directions without physical moving but instead steering the signal electronically (by selectively delaying some of the signals precisely).

Do some modern VORs implement a similar technology and use this to rotate the signal 360 degrees instead of physically spinning?


texts: Can a MEI CFI give a valid flight review in a plane for which he is not endorsed?

texts:
A friend of mine is working towards his initial CFI.  I'm helping him work through regulatory, weather, and other knowledge stuff when time permits.  During our most recent ground session he asked me a question that I had never been asked.  Here's the setup...

A CFI with a freshly minted MEI (airplane, land) is asked to conduct a flight review for a customer in the customer's own Cessna 421C, a pressurized piston twin certified to >30,000'.  This CFI has only flown one type of twin (pick a common training twin, doesn't really matter).  He has no time at all in a 421 of any sort or any other twin aside from the trainer in which he trained for his commercial-multi and MEI.  Our MEI is otherwise current in all categories and classes for which he is certified, holds a complex endorsement gained during his commercial training, and holds a First Class with no limitations.

The customer is current in all categories and classes for which he is certified, is within the 24mo flight review window, and has a First Class.  In short, the customer is fully qualified to be PIC for the flight portion of the flight review.

What's obvious:

The five hour rule does not apply since a flight review is not
instruction given for a certificate or rating.
Our MEI cannot act as PIC of the customer's 421C because the MEI is missing a high altitude endorsement and a high performance endorsement even though he is category and class certified for airplane multi land.
A CFI does not need to be PIC, or even hold a medical, in cases where the student/customer is able to act as PIC.
Edit: it's a really bad idea to do fly an aircraft type with which you are not familiar.

The question is this:
Can our fresh MEI give the customer a valid flight review in the customer's 421C?


texts: why is rhumb line bearing for this question 270 as the answer?

texts:
An aircraft leaves position "G" in lat 40 degree South and flies the following Rhumb Line tracks and distances:
G to H : 180 (true) 240 NM
H to J : 270 (true) 240 NM
J to K : 000 (true) 240 NM

what is the rhumb line bearing from G to K ??
According to me answer should be 090 but it is given as 270 ..
can someone please give the reason for the same


texts: What will happen if an X shape wings mounted on biplane?

texts: The question is What will happen  if an X shape wings mounted on a light biplane? What will happen in the place which upper wings come closer to lower wing?


texts: Is a 5 hour 3 session process normal for a plane checkout you're already trained in?

texts: I've joined a flying club and am in the checkout process for their 152. I've trained in it, was endorsed by a 20,000+ hour instructor (who felt comfortable enough renting his personally owned 152 to me after the checkride), and my DPE (who a commercial pilot tried to steer me away from due to her supposed high fail rate, i.e. she's demanding) thought I flew the plane well. I'm a very new VFR pilot with about 70 hours total, and find this checkout process is taking longer than usual under these circumstances. Has anyone gone through a similar situation? How have they dealt with the matter? The instructor is also making me feel less safe as a pilot doing things like banking with full flaps, and pushing "flap religion" on me (i.e. 10 on DW, 20 on base, 30 on final without really considering the approach environment). Due to W/B restrictions on the 152 he's the club's only viable checkout instructor.


texts: Where should I enter the pattern when instructed to report a 2-mile left base?

texts:
Say I'm flying heading 275 and am headed in to land on runway 16 at a towered airport in Class D airspace. I'm 8 miles to the east and have been cleared: "report 2 mile left base runway 16". Should I go for a standard 45 degree traffic pattern entry to downwind at midfield or should I fly straight to the base and report when 2 miles east of the runway?

In this case I went straight for the base and reported and didn't get yelled at by the controller but I'm curious what the correct thing to do is in this situation.

I'm not asking what a 2 mile base is, I'm asking where I should enter the pattern if instructed to report on 2 mile base.


texts: When does fuel indicator indicate red index? C172

texts: Full fuel is 56 gal and usable fuel is 53 for c172r. Other than when the fuel indicator is broken, when the fuel indicator indicate red index? Is there any fuel quantity setting to indicate red?


texts: Do crosswind takeoffs increase the chance of a compressor stall?

texts:
I watched this video on YouTube:

The video shows some pretty impressive take-offs in serious crosswind. Honestly, they looked even scarier than crosswind landings.

It also made me wonder: In such conditions, when there is significant yaw due to the crosswind, and paired with the high engine setting, isn't there a significant risk for compressor stalls? Are there some formulas for calculating maximum crosswind particularly for takeoffs, or something like that, taking into consideration engine performance/response?


texts: Is it possible to get permission to fly a quadcopter around the St. Louis Arch for non-professional means

texts: Is it permissible to fly a small quadcopter (<1 kg) around St Louis Arch for non-commercial means? If so what permit/permission is required?


texts: What are the adverse effects of keeping the PACKs on the A320 running with the LP air conditioning unit connected?

texts:
I had come across this statement will reading the limitations chapter in the FCOM. But once again there is no reasoning given for it I have also read the air conditioning systems chapter but can't seem to find an explanation.

Can someone explain the reasons?


texts: Why would the front edge of an aileron fold outward?

texts:
I was just enjoying a movie of one Svetlana Kapanina flying her EA300. One camera looks out of the cockpit over the left wing. In a couple of scenes, the aileron of the wing can be seen quite clearly. The picture (see 1) shows it deflected downward, except for the red "end" deflecting upward. Other scenes show that when the aileron deflects upward, the red "end" turns downwards.

What is the reason to have this red "end" tilting in opposite direction to the aileron?

NB, you can enjoy the whole movie here:


texts: How many Harriers crashed at or near MCAS Cherry Point?

texts:
When I was stationed at MCAS Cherry Point in the last 1970's we had a Harrier flip over and crash while practicing at the hover pad. It took off in the direction of our large hangar and thankfully went into the other side (depot maintenance) instead of ours (SOES) where we had a C-9B, T-39's and CH-46 aircraft, all fully fueled. I came back from lunch to find the Harrier in the parking lot at the other side of the hangar, after it having plowed through what was left of another Harrier crash, among other things.

I was wondering... how many Harriers were lost in or near Cherry Point? Anyone know?


texts: Why the dynamic pressure is not mentioned in the explanation of lift by Bernoulli's principle?

texts:
Usual "explanation" of lift using Bernoulli principle

This theory is:

Air over the wing is accelerated, its dynamic pressure increases with velocity.
The static pressure over the wing decreases (due to Bernoulli principle, see below).
The opposite occurs below the wing, static pressure increases.
This results in an imbalance in static pressure between sides, and explains lift origin.

Source

Bernoulli's principle

Bernoulli's principle explains "an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy":

$$p + \frac{1}{2}\rho V^2 + \rho gh = k$$

where $k$ is a constant. In the case of a wing, $\rho gh$ is so small it can be omitted, the principle can be stated:

$$p_0 = p + \frac{1}{2}\rho V^2$$

where $p_0$ is a constant known as total pressure, the first term is the static pressure, and the second one the dynamic pressure.

The explanation of lift ignores the imbalance of dynamic pressure

The previous theory ignores a similar, but opposite, imbalance of the dynamic pressure (as the total pressure is constant, the arithmetic sum of the two imbalances is also constant):

Why is the force created by static pressure put ahead in the explanation of lift, and the force created by dynamic pressure is not mentioned? If this force is ignored because not significant, why and how much is this force smaller?


texts:
I was watching this video:

At around 1:28 I heard the controller clear a plane to descend to a level "given rate". I was searching online but couldn't seem to find what they meant with the term 'given rate'.

Could it be the "level change" or "open descend" button in the aircraft?


texts: Has anybody done gliding experiments with exact replicas of the birds or other real world flying creatures?

texts:
The most obvious way to verify if birds are stable or not in at least gliding flight would be to make the exact rigid model of the bird (including weight distribution) and launch it into flight. The simplest approach that even early aircraft inventors may have tried is to use a frozen real bird.

Are there any references about anybody trying such experiments? Pure logical or mathematical analysis is outside the topic of this question.


texts: What are RNP and ANP in area navigation?

texts: What are Required Navigation Performance (RNP) and Actual Navigation Performance (ANP)?


texts: What are the ejection injury and fatality rates?

texts:
Most of us have probably heard about how ejecting from a military aircraft is dangerous in and of itself, and that ejection is not a get out of jail free card.

The most common dangers seem to be:

Lacerations during the ejection, by failing to clear the cockpit.
Concussions caused by collisions with the canopy or fuselage.
Insufficient altitude or speed to deploy a parachute before impacting terrain.
Other assorted hazards associated with parachuting down in an unprepared location.

There exist a number of openly-available reports on the topic, from several different countries and time periods that could serve as a starting point.

I have multiple closely-related questions, so I hope it will be self-evident why I chose not to split them up, but feel free to focus only on the first one:

What are the odds of surviving an ejection from a military aircraft? We can presuppose a fit crew member, but make no further assumptions about the particular case.
How likely is the crew member to sustain injuries?
Are there any significant trends in the data, e.g. introduction of 0-0 seats, survival procedures, sub- vs. supersonic ejection?


texts: What are the approximate glide angles for modern passenger jets?

texts: What is a typical glide angle for a modern passenger jet with engines idling, with full flaps and with the gear down?


texts: Are aircraft capable of sustained inverted flight at constant altitude?

texts:
Inverted flight as a part of manouveres, dogfights, acrobatics is fairly common but my question is:

Are any aircraft capable of sustained inverted flight without losing altitude? e.g. Could you fly 10 mins inverted at the same flight level?

To clarify: I'm not wondering about engines, fuel systems, air-frame strength etc. Fundamentally there's no reason why those systems cannot be engineered to be robust against inverted flight.

What I'm curious about is specifically the aerofoil itself.

i.e. As far as I can see, you'd need to balance the gravity vector with lift.

Ergo, are aircraft wings generally capable of providing enough compensating lift in the "wrong" direction to balance gravity? Are all / most fighters / arerobatic certified craft capable of this?

We'd need an aerofoil that can provide a lift vector pointed in the +z direction normally but changable to a large vector pointing in the -z direction in response to a flight surface deflection?


texts: Is it legal to fly under the Golden Gate Bridge?

texts:
I recently had the opportunity to rent a plane and fly in the San Francisco Bay Area.  While flying in the HWD/OAK/SFO area is challenging enough, when I spoke of my adventures of flying above Alcatraz and the Golden Gate Bridge, some of my fellow pilots asked me if I flew UNDER the Golden Gate Bridge and voiced their desire to do so.  As a relatively new pilot (3 months), while flying is definitely an adventure for me, flying under a suspension bridge is pushing my minimum safety limits and just does not seem lawful.

Others have told me that they have seen GA aircraft fly under the bridge. While I'm sure pilots have done it...I don't see how this can be legal.  According to sources on the internet the bridge is only suspended 270' above the bay.  It doesn't seem enough space to fly through legally.

According to 91.119

Except for takeoff or landing, no person may operate an aircraft below the following altitudes;

a. Anywhere. An altitude allowing, if power unit fails, an emergency landing without undue hazard to persons or property on the ground.

c. Over other than congested areas.  An altitude of 500' feet above the surface, except over open water or sparsely populated areas. In those areas the aircraft may not be operated closer than 500' to any person, vessel, vehicle, or structure.

To me, 270' does not meet the legal requirements set in 91.119(c)  I don't consider the SF Bay or water under the bridge to be "open".

So, is it legal to fly under a suspension bridge like the Golden Gate or Verrazano-Narrows Bridges?


texts: Where can I find the latest METAR and TAF for RPVK / Kalibo International Airport?

texts:
What website holds the latest METAR and TAF for RPVK / Philippine weather?
In aviation weather the information does not exist at all times.

Could you suggest an other website that provides the required information.

Thanks for the help!


texts: To what extent (if any) is it possible or desirable for the pilot of a large airliner to "fly by the seat of the pants"?

texts:
I recall that some years ago the pilot of the A340'S first flight described its handling as "like riding a bicycle" (to me this would mean that as he went past his favourite bar he saw his friends inside so he propped it up against the wall to have a drink with them).

I can believe that despite its size and weight a large airliner would respond precisely to commands, but does the concept "flying by the seat of the pants" apply to such an aircraft?

Obviously experience and training will build up a great deal of intuition (visual, vestibular, etc) - what sort of bodily connection does an airline pilot experience with the aircraft? Is it markedly different from that of the pilot of a small plane?


texts: What's the purpose of the fairing on fuselage, near leading edge of the wing?


texts: Light Plane: Transition to Right-Seat Flying: How to Prepare, What are Common Errors?

texts:
I'm preparing to start my CFI training and have almost exclusively logged all my time from the left seat of a Cessna 172 or 182. Is there a standard training program to transition to flying from the right seat? If not, how do people generally prepare, in an effort to make this less opinion-based, what are some common errors that pilots might make when learning to fly from the right seat?

Related: Is an approval required to fly from the right seat?


texts: What is the thick, dashed, magenta line on a sectional chart?

texts: In the attached area of the sectional chart we see restricted areas R-2101 and R-2102. Also covering that general area is a circular, thick, dashed magenta line. There's a notice there that I assume corresponds to it, but I wasn't familiar with this marking before I saw it. I glanced at the Aeronautical Chart User's Guide but didn't see a reference. Anyone know what's happening here?


texts: Is a holding pattern always counter-clockwise? Or is it dependent upon the controlling airspace?


texts: Do stunt jets use laser distance meters to align with one another to maintain formations?

texts: My question is about Jets/planes performing acrobatic formations to stay well-aligned with the other jets/planes in formation. I could see a laser-distance meter coming in handy.


texts: Does leading-edge droop increase or decrease lift, other things being equal?

texts:
Consider a conventional subsonic airfoil in level flight. Typically it is cambered and with a small positive incidence, both of which features contribute to lift.

Now droop the leading edge, as with say a plain leading-edge flap. This reduces the incidence, possibly even taking it negative, but increases the camber. Will the net lift increase or decrease, and why? Can the answer vary according to other flight conditions?


texts:
In the 3D case,downward turning is immediately above and below the wing is stronger than in 2D case,for the same lift.This is because more rapid dying off the pressure above and below the airfoil means the vertical pressure gradient near the wing surface is stronger than in 2D case.The airfoil pressure field dies out more rapidly ahead of the airfoil and behind,which results in less upward turning of the flow in this region.So in 3D case we have more downward turning above and below the wing and less upward turning ahead and behind.Vertical extent of pressure distribution in 3D is lower than in 2D for the same chord and lift per unit span.
Reducing vertical extent of pressure distribution means increase  pressure gradient close to the wing surface and a reduction far from the surface.

So in short, smaller vertical extent(small pressure field) of pressure=larger pressure gradient=larger force which drives downward accelaration.

Pressure gradient=delta pressure / distance (Pa/m)

Do you see some contradictory in explanation above or everything is logically?

because,when we increase AoA,vertical extent of pressure distribution is larger so pressure gradient is smaller and downward acceleration must be also smaller,but it isnt because with AoA rise downward turning(downwash) as well.

Can someone explain in detail what happend with pressure fields,pressure gradient in relation to upwash/downwash at 2D/3D wing and when change AoA...


texts: Is Saudia's 777-368ER The Longest Passenger Aircraft?

texts:
I watched a video about passenger aircraft length (video was removed from YouTube)
It says the longest passenger aircraft is Saudia's 777-368ER.

Saudia web site says their 777-368ER is 78.86m.
But according to the Boeing web site, 777-300ER is 73.9 m.

Is the 777 be able to made longer as customer option?
I couldn't find any news souce about Saudia purchasing a modified 777.


texts: How is the terrain displayed on the ND in a A320?

texts:
When you turn on "TERR ON ND" in a A320, you see terrain info on you navigation display (ND), but where does its source come from ?

if data comes from FMGS stored inside its memory, then how come it cannot display it in all bounds of the display (see picture) ?

if data comes from the nose radar, then how is it possible to see oceans when you're on the ground in an airport, say in JFK for example ? The radar beam would never be able to get to the water directly.


texts: What is the difference between MEL and CDL?

texts: I know the MEL and CDL are the minimum equipment list is provided by the manufacturer, if component missing or damaged means the aircraft must pass the MEL and CDL, I need some suggestions how it was actually working in aircraft maintenance


texts: What does "RA" mean in the FAA Terminal Constraints?

texts:
I'm trying to interpret the Terminal Constraints listed on the Operations Plan Advisory (https://www.fly.faa.gov/adv/adv_spt.jsp). RA seems to be used in the context of weather, but I haven't been able to find a definition for what "RA" means other than "Resolution Advisory" which I don't think is applicable in this context.

Example:

TERMINAL CONSTRAINTS:
NY METS/PHL/DC METS-RA/LOCIGS
CTL/ATL/MCO/TPA/FLL/MIA-RA/TSTMS


texts: How does ATC radar/ADS-B ground stations not get confused with signals sent from multiple aircraft?

texts:
I understand that the radar sends a 1030 MHz interrogation signal to an aircraft and the aircraft's transpoder responds using 1090 MHz. When it comes to Mode S squitter, the transmissions are unsolicited (does not require interrogation). Considering that the airspace is highly populated, there would be multiple aircrafts transmitting data on the 1090 MHz to the radar. Won't these signals interfere with each other and become a huge mess at the radar side?
(Similar is the case of ADS-B, where data would be continuously broadcasted between aircraft-aircraft, aircraft-ATC and vice versa on the 1090 MHz Extended Squitter, how are the signals prevented from mixing up with each other?)

Also how is the interrogation signal transmitter from ATC to aircraft (and also back) sent? Is Frequency modulation used here? What is the bandwidth of the 1090 Mhz channel? Does it have sidebands?


texts: Is it recommended to get a life raft for short overwater operations?

texts:
I'd like to fly to Santa Catalina Island (AVX) from the mainland around Los Angeles.  There is a portion of this overwater flight where my Cessna 172 will be beyond gliding distance from land.  I know that people usually do this flight with only life jackets, but the water is about 64 degrees F (18 °C) right now and I'm pretty sure that if I needed to make a forced landing in the water I may have hypothermia before rescue arrives.

Is it recommended to take an aviation life raft?  They're pretty expensive - they start at US$1000 for a two-man raft.  I see that raft rentals are available, but that's kind of a big pain, especially because they are going to be shipped from some other location and there is the possibility of needing to reschedule the flight because of weather.

What are the recommendations of authorities? Is there any alternative equipment that would be as effective in this scenario?


texts: What is the typical voltage used on jet airliners?

texts: I have seen several parts that use 28 Volts DC, is this a standard for jet airliners (e.g., Airbuses and Boeings).


texts: Cabin crew : how do they get Oxygen in the event of decompression?

texts:
According to this answer, in the event of an explosive decompression it can take as little as 9 seconds to develop problems without an Oxygen supply.

How are cabin crew meant to get to an oxygen supply when they're a long way from their allocated seat ? There's not only distance to consider but if they're jammed between two carts in the middle of meal service they're not going anywhere too quickly !


texts: How do "tip jet" helicopters cancel the torque effect of the main rotor?

texts:
Some helicopters use "tip jet" on the rotor blades tips such as the McDonnell XH-20 Little Henry and Hiller YH-32 Hornet.

How do they cancel the rotor torque (often canceled by the tail rotor)?


texts:
After taking a new plane from the manufacturer's factory to its airport base, the plane must undergo a Certification Flight before starting to operate with the airline:

What is a certification flight?
What is the purpose of it?
What are the tasks done on a Certification Flight?
Why doing a Certification Flight if the aircraft has already been tested before?


texts: What makes spiral instability less harmful than Dutch roll?

texts:
The FAA Pilot's Handbook of Aeronautical Knowledge says on page 5-20:

  Because it is more desirable for the aircraft to have “spiral
  instability” than Dutch roll tendencies, most aircraft are designed
  with that characteristic.

What are the grounds for that?


texts: Why are different routes flown between the the same pair of airports?

texts:
On two of my trips (same airline, same kind of plane 777), I noticed that the airplane took very different routes (from New York to UAE).

1st Trip in 2012 (blue): Duration 11h 30m

2nd Trip in 2013 (green): Duration 13h 00m

I know that the blue line is the shorter distance, and probably also because of jet streams, it took lesser time. But why a plane would take this green route, even not considering jet streams?

Since I am not an important person, I could not ask the captain of the plane this question at the end of journey.

P.S.: I observed the flight paths on the entertainment system this airline has for all passengers.


texts: Can a US pilot residing in the EU fly N-reg under IFR on a US PPL?

texts: I am a US citizen living in the Netherlands, and I have an FAA PPL(A) with current IR as well as an EASA PPL(A) without IR.  I am currently trying to figure out my easiest path to IR conversion, as I do not have the required 50 hrs PIC time to do a direct conversion.  I know I can do the CBIR, but I'm wondering if I'm permitted to fly N-reg aircraft under IFR in order to build the required hours.  I've heard that as an EU resident I'm required to fly using both an EASA PPL and FAA PPL in an N-reg, and therefore I assume the answer is technically no.  Am I correct in this assessment?


texts: How much runway does an amphibious Cessna Caravan require for VFR part 135 operations?

texts:
I am trying to determine the length required for us to build a simple paved runway for a Cessna Grand Caravan EX Amphibian to depart for water landings and and return (VFR/VMC only, Part 135).

Previous questions about for "runway length required" only refer to Part 135 and Part 91 for Large Transport Category.


texts: What are the fuel requirements for Canadian flights?

texts:
I am aware of the "US Flag Jet", "Piston" and "Domestic" policies in the US, and the ICAO policies. Is there a specific requirement in Canada for domestic and also international flights? Does Transport Canada have their own regulations, or do they use the ICAO or US ones?

I'm asking this for use in simulation but I'd imagine this is also a valid question in the real world.


texts: Why are there so few high-wing jetliners?

texts:
So far, we have only seen a few civilian jet transports with high wings. All of them BAe 146, Do 328JET, seem to be regional jets. Yet military jet transports are almost completely high-wing. Why aren't we seeing high-wing large jetliners?
Some advantages of high wings:

shorter landing gear
easier access to the fuselage
a better location for the center-of-thrust.
better stability
better ground clearance for upcoming high-bypass turbofans. Lack thereof caused the design changes that ended in 737 MAX crashes
Increased flap efficiency
better able to take advantage of strut-bracing, if any.

Some disadvantages:

less efficient location of landing gear. (probably not mounted on the wings)
more likely to tailstrike
passengers may mock
belly landings could be tricky
water landings may be even more tricky

I don't know how these pros and cons add up though. Can someone give some more info?


texts: Why do the emergency oxygen masks for some 787 premium class seats have an extra 'streamer' to pull them down?

texts:
Specifically, on Norwegian 787s, you are briefed:

  "In economy seats, reach for your mask. In premium seats, pull the
  streamer for the mask to drop the full distance."

(source)

Now the overheads in premium and economy appear identical:

(Source)

And the premium seats are merely larger versions of economy, they're not beds or fully-reclinable. They're set 2 - 2 - 2 rather than 3 - 3 - 3. I'm guessing there are just two masks in each premium overhead where there would be three in economy, but that doesn't explain the "streamer" (which is just a piece of red cord).

So in premium there's an extra step; of course you end up with exactly the same mask. It puzzles me what the thinking is for the "streamer".


texts: What is the derivation of 15 and 11.3 used for estimating pivotal altitude?

texts:
Pivotal Altitude Explained: Teaching eights on pylons the easy way at AOPA repeats a common formula for pivotal altitude.

  To estimate pivotal altitude, square the groundspeed and then divide by 15 if you use mph, or 11.3 if you prefer knots.

Where do the 15 and 11.3 magic numbers come from?


texts: Guidelines for using a constant speed/adjustable pitch propeller

texts:
I have been trained in a single engine fixed pitch prop ( C152). I'm trying to move to Piper Arrow II which has an adjustable pitch propeller. I understand how constant speed propellers work. I'm trying to understand how to use this new feature in cruise flight.

My understanding is that in the highest RPM configuration, the propeller will provide the highest thrust. This implies that the lower RPM will result in lower thrust ( true? ). If the objective is to get to the destination in the shortest possible time ( the most common objective ) why would anyone want to mess with the pitch of the propeller?

I understand that using a lower RPM may have other advantages like lower engine temperature, lower noise and possibly longer engine life. I'm hoping there is an answer like: ( you can reduce the pitch but maintain cruise speed ..) :) OR for a significant reduction in noise level you will sacrifice 5kts in speed.

This answer doesn't answer my question.


texts: What's the formula to calculate static air temperature?

texts:
What's the formula to calculate external temperature (static temperature) of an aircraft, given that I have Mach, TAS and altitude?

Since I don't know the formula, I tried to search on Google. But I found that I need total air temperature, which must be know by a sensor (and I don't know). So, is there any other formular/way to calculate static air temperature using only mach/tas/altitude, or is not possible with only these data?


texts:
Background:

I'm an 18-year-old Finn and so I'll be starting my military service next summer. I'm currently applying to the Air Force to become a fighter pilot, but I don't have any previous training in aviation. I have studied a bit of theory from the internet but I just want to ask what would be the most relevant information for someone trying to become a fighter pilot.

So the quistion...

What should someone, who's wanting to become a fighter pilot, try to learn and in what order? And what are good resources for learning those things?

Thank you in advance!


texts: Are there any aircraft where the wings are swept forward of the cockpit?

texts:
Are there any aircraft where the wings are swept forward to form a C shape ahead of the cockpit? Something like this:

  --  --
 //    \\
 || /\ ||
 || || ||
 \\_||_//
  \____/

I want to do a research on that kind of aircraft and there are many science fiction examples, but I wonder if there are any real-world ones? If so, what is that wing configuration called?


texts: Are jet streams a net benefit in time and fuel savings?

texts: Suppose a plane has a cruise speed of 400 knots  TAS. In a 4000 nm route we would have a round trip of 20 hours. If there was a jet stream of 100 knots in either direction, we would have 4000/500=8 hours in the tailwind direction and 4000/300=13.3 flying into the jet stream for a total of 21.3 hours. Now clearly, airlines are smarter than this and plan flightpaths, altitudes and speeds that maximize tailwinds and minimize time spent flying against the wind. The question, is to what extent does this strategy help? Does it simply offset the time lost compared to flying at the same speed in both directions? Or does it help even more than that. In other words, would a hypothetical windless world hurt the airline industry?


texts: Could there ever be a fully solar powered airliner capable of transatlantic flights?

texts: Could a new or a modified existing airliner, e.g., a Boeing 737, be fully powered by solar energy and make the normal length trips aviation-fuel powered aircraft make?


texts: Has there ever been a plane with reversed flight controls?

texts:
Has there ever been a plane which at least one of the primary flight controls is reversed?

For example, pulling back on the stick will cause a dive, or full throttle is achieved by moving the levers backwards towards the pilot.


texts: Do aircraft manufacturers take steps to prevent pests like geckos from damaging the electronics?

texts:
Many Australians are suffering huge bills due to geckos getting into the circuit boards of their air conditioning units. Of course this is highly profitable for A/C manufacturers as they supply replacement boards on a virtually annual basis. I noticed in my unit that a simple fine mesh would have been sufficient to keep them out of the critical space where the circuit boards are.

My question is: do aircraft have the same potential problem and are aircraft manufacturers taking any steps to prevent this?


texts: How do you determine the proper rate of descent for landing?

texts:
I'm trying to use a simulator to learn to land properly.  One part that I'm finding really tricky is picking a proper rate of descent.  I know I'm supposed to do my best to keep it so I have two red lights and two white lights on the Precision Approach Path Indicator (PAPI), but at the moment I basically am just eyeballing it and adjusting my course whenever the lights aren't right.

I have to assume, though, that for any given airspeed there is a rate of descent I can maintain that will keep me right in the middle of the preferred glide slope for that airport.  I just have no idea how to figure it out.  Is there an application or formula that is preferred for this?  Or is it time to learn Vector Calculus?

PS- I did check this question to see if it related.  But that question is about starting the descent from cruise.  I'm talking about rate of descent for final. I did also check this answer, but it's about using the PAPI/VASI lights.  I'm looking for a formula to figure out the proper rate of descent during final for a given speed.


texts: Where is the toilet smoke detection indication displayed for a B777-200/300?

texts: In case of smoke detected in any of aft toilet of a B777-200/300, where is the indication displayed? Is this at a single location, or at different locations?


texts:
Participation in TRSA services is completely optional. The depicted airspace is all still class E, and you can fly straight through it sans radio or transponder without violating any regulation.
Obviously, if you do talk to them, they can provide radar services, but this is no different from any other class E airspace owned by an approach facility, including (notably) the class E above and below the depicted TRSA boundaries.
So, why bother showing it at all?  And even if there’s a reason to show it, what’s the point in such complex configurations that have zero impact on either pilots or ATC?


texts:
I used to think that for commercial aircraft from Airbus, Boeing, Embraer, etc., the take off power was always maximum and selected by the TOGA selection on the thrust levers. But I have been told that some companies would lower the takeoff power to save money (at the expense of a longer take-off length).

So the question is: for regional, continental, and long-haul aircraft, is the takeoff power always maximum or can it be adjusted depending on the configuration? And can lowering takeoff power allow savings?


texts: Current FMS with COMM tunning function capability?

texts:
I am currently more familiar with GARMIN 1000 systems than with the ones that are used nowadays in airliners.

I know that you can tune a NAV aid from the FMC in an airliner. Actually, modern FMS come with the auto-tune capability for NAV aids (which helps to achieve the desired RNAV or PBN requirements). My question is if there is something similar regarding the COMMS frequencies. Let me elaborate:

With Garmin 1000, you can even select COMMS frequencies from the FMS. You can actually search an aerodrome and, if selected, it will automatically tune the COMM frequency for that aerodrome in the standby freq. Therefore:

Is there any mechanism like this one in the FMS of typical modern airliners? (a320, b737, a380...). If not, could you please give me examples of typical GA aircrafts that come with FMS with that capability?
Is there any way that we can we select comms frequencies from a typical FMS in an A320 or B737, or do we have to use always the nav/comms station to do so?


texts: Why would a C150 tachometer be sluggish?

texts:
After having an issue with a tachometer bouncing so much that it fell off, I now have the opposite problem with the replacement (Mitchell D1-112-5025): The tachometer is sluggish. When I open the throttle from 1,000 to 1,700 for the runup, the tachometer takes about 6s to show 1,700 RPM. The delay seems even more pronounced when I reduce power. The smaller the change in RPM, the longer it takes the tachometer to update.

My A&P says that it just needs breaking in, which could possible because the sluggishness has reduced since the tachometer was installed; however, I was under the impression that modern tachometers should work without sluggishness immediately.

The counter increments as expected.

How should I approach this problem? Is it common for tachometers to need >15 hrs to break in? Is it possible for a drive cable to cause this issue (continue to spin, but in such a way that the tach speed is sluggish)? Could some kind of installation issue have caused this problem?

UPDATE Mar-22: Removed the tach cable, inspected outer and inner cable, washed, dried, lubed with graphite, and replaced. Cable seemed good, but the tachometer is still sluggish.

UPDATE Mar-24: Tachometer is now beginning to exhibit the same symptoms as the previous tachometer before the needle spun off; the tach is still sluggish, but the needle is now bouncing considerably.


texts: Are there any aerospace examples of applying a boat tail?

texts:
A way to reduce the pressure drag of bluff bodies is to apply a tapering of the tail (so called boat tailing)

I know some (extreme) examples of this method of drag reduction applied to cars:

Source

And I know that this a feature of the Very low drag bullet

Source

I was wondering if there are any aerospace applications?


texts: How often do military pilots train to retain muscle memory for use of weapons systems?


texts: Is airspace above KKIC class G at 3,500’ MSL?

texts:
Flying from KPRB to KKIC, in a straight route shown on SkyVector, except keeping slightly to the East of R-2504A&B, holding an altitude of 3500MSL, except for normal takeoff and descent rates, am I correct in the following?

Taking off from KPRB, you're in Class E airspace within the dashed magenta lines.
Once you're out of KPRB's dashed magenta lines, all the way to landing at KKIC, you're in Class G airspace.

I'm watching a video from PilotEdge, and at 47:33 he roughly says "We know we're going to be in Echo as we take off.  We're going to be in Echo for the rest.  We know we're in Echo by default, because there's nothing else around."

I think the "We're going to be in Echo for the rest" part is wrong.  Am I correct here?  If I'm wrong, can you please explain why it's Class E?  It's not within a fuzzy blue or magenta line, and we're flying at 3500MSL, so obviously never going above the Class G 14500AGL ceiling.

I think he's just simplifying things because in another video said VFR pilots in the air can practically treat all Class G airspace as Class E, not using the less restrictive weather minimums, and be safer.  But, starting to learn aeronautical charts and flight planning, I want to know if I'm fundamentally starting with a misunderstanding or not.  The YouTube video has no comments about this statement.


texts: How can I build the 40 hours instrument time required for an instrument rating?

texts:
14 CFR 61.65(d)(2) says:

(2) Forty hours of actual or simulated instrument time in the areas of operation listed in paragraph (c) of this section, of which 15 hours must have been received from an authorized instructor who holds an instrument-airplane rating, and the instrument time includes:

So 15 hours must be with an instructor.  What about the other 25?  Can I fly in instrument meteorological conditions (IMC) "solo" (not the hood) like I did for my private pilot license (PPL) after an instructor sign off?  Or does this just mean that I need another instrument rated (IR) pilot with me, but it doesn't necessarily have to be a certified flight instructor (CFI)?  If that is the case, and I use the hood rather than actual IMC, does the other pilot need an IR or just a PPL?
Basically, how do you fulfill the other 25 hours?


texts: Is it possible for the sensors which determine when an aircraft has landed in water to become damaged?

texts: A plane has sensors that should transmit data back somewhere when it hits water correct? Is it possible that these can be turned off/damaged?


texts: Could a hybrid electric steam plane be more efficient at altitude than at sea-level, and how to optimise it to frigid air?

texts:
In the thirties a steam powered plane was built.
video

Could a hybrid electric steam plane be more efficient at altitude than at sea-level, and how could such a steam engine be optimised to benefit from frigid air at altitude?

Perhaps there are two advantages to going hybrid.

The steam engine can be down sized to cruise power levels.
The radiator is being cooled by frigid stratospheric air < -40 deg so can be smaller.

This is a parallel hybrid, the electric motor drives the propeller until the plane is at altitude. Once at altitude the electric motor is disengaged and the small steam engine starts up and engages with the propeller.

[edit]

There is a replica of the Besler engine at the Smithsonian. It has more specs than the video. It had a condenser

Steam Car Developments
and Steam Aviation, VOL. III. JUNE, 1934 NO. 28., The Besler Steam-Driven Aeroplane

'Under the fuselage nose is the condenser, which is simply a section of an ordinary petrol car radiator, and this is said to be sufficient to recover more than ninety per cent. of the water from the exhaust steam.'

'The tests have shown that ten gallons of water is sufficient for a flight of 400 miles.'


texts: What is wrong with my understanding about total pressure for a rocket nozzle?

texts:
I’m using the ideal rocket equations and isentropic flow but cannot determine what is wrong in my understanding about total pressure. Can anyone explain where I am wrong using the following example?

Example:

$\gamma = 1.4 $

Converging-diverging nozzle Area ratio $A/A^\star = 12.0$

Inside the rocket chamber $P_0 = P_t = 12 MPa$

Exit area $A_e = 0.002 m^2$

Mass flow rate $\dot m = 2.5kg/s$

$Thrust=5000N$

Supersonic flow

Atmospheric pressure $P_{atm} = 101.3 kPa$

Solution:

Based on isentropic equations - (e.g. https://www.grc.nasa.gov/www/k-12/airplane/isentrop.html)

Mach No. $M = 4.127$

$P/P_t = 0.0056$

$T/T_t = 0.227$

Substituting in $P_t$ gives:
$P = P/P_t * P_t = 0.0056*12 MPa = 67200 Pa $

Then based on the ideal rocket equation (i.e. https://www.grc.nasa.gov/WWW/K-12/rocket/thrsteq.html)

$Thrust = v_e * \dot m + A_e (P-P_{atm}) $

Rearranging for exit velocity:

$v_e = \frac {Thrust - A_e (P-P_{atm})}{\dot m} $

$v_e = \frac {5000 - 0.002 (67200 - 101300)}{2.5} = 2027.28 m/s$

Then the exit density can be found by rearranging this (also from the isentropic equations website):

$a = \sqrt{\gamma \frac{P}{\rho}}$

Rearranges into:

$\rho = \frac{\gamma P}{a^2}$

Speed of sound
$a = v_e / M = 2027.28 / 4.127 = 491.22 m /s $

Substituting into the density equation:

$\rho = \frac{1.4 * 67200}{491.22 ^ 2} = 0.390 kg/m^3$

And here is the problem/confusion:

From the question the total pressure is $P_0 = P_t = 12 MPa$
This is also supposed to be the total pressure at the nozzle exit because it is reversible/isentropic flow.

But $Total Pressure = Static Pressure + Dynamic Pressure$
$Total Pressure = P + 0.5 \rho v_e^2 $
$Total Pressure = 67200 + 0.5 * 0.390 * 2027.28^2 = 868624 Pa$

And this is nowhere near 12 MPa... so what part am I not understanding correctly?


texts: Did Kai Tak have a straight-in approach to runway 13 for higher-performance aircraft?

texts:
Runway 13 at Hong Kong’s Kai Tak Airport (closed in 1998 and replaced by the current airport at Chek Lap Kok) had a hideously difficult approach in which pilots would fly in from the west, following an instrument guidance system (IGS)1 to the approach’s middle marker (also helpfully marked by a giant checkerboard painted on a hillside, which, if not spotted in time, required a missed approach), and then immediately hand-fly a steep right turn2 at very low altitude directly over the heart of Kowloon City to line up, seconds before landing, with the runway, using only the Mk. I eyeball for guidance, with no room at all for error.

For obvious reasons, only the best of the best pilots were allowed to shoot the bent approach to runway 13, and only after extensive simulator training for that specific approach, and even they had considerable trouble with it, even in good weather.

The bent approach was necessitated by the presence of an inconsiderately-placed mountain in what would otherwise have been the runway 13 approach path, which, for a straight-in approach, would have forced the use of a glideslope too steep for a widebody jetliner to safely fly.  Not all aircraft (or even all airliners) are widebody jets, though, and smaller, higher-performance aircraft (including virtually all STOL aircraft) can frequently shoot approaches much (much) steeper than what would be safe for a 747 or A330.

Given the difficulty and hazard of the standard bent approach, did Kai Tak have a straight-in approach to runway 13 for use by steep-approach-certified aircraft?

1: Like an ILS, except that following the IGS all the way down would kill you.

2: I don’t know if the Kai Tak checkerboard turn would technically qualify as a pylon turn, but it must surely have come close!


texts: Why not tow aircraft instead of single-engine taxi?

texts:
To save costs, budget airlines could potentially eliminate the single-engine taxi that is standard.

Companies are looking into things like electric motors on the wheels of airliners for taxi, which could be powered by the APU, using much less fuel than even a single-engine taxi.

But why not just tow all of them using existing towing equipment?

The related post 'Does it make sense towing airplanes to the head of airstrip by electric means?' asks for electric technology (internal or external), this one asks about using existing technology.


texts: What percentage of professional pilots end their career early for medical reasons?

texts: As an amateur pilot I'm aware that I can lose my medical at some point and have to give up flying.  For a professional, losing a medical can end their career. I know several people who wouldn't even get a PPL with their medical history. Are their any figures on the number of CPLs/ATPLs that lose their livelihood for this reason?


texts: On a constant speed propeller, how is blade pitch related to airspeed and efficiency?

texts:
I'm trying to wrap my head around what the PHAK (Pilot's Handbook of Aeronautical Knowledge from the FAA) states for constant speed propellers.

First, why is it that if airspeed increases, for a fixed RPM, your blade pitch will increase, and conversely decrease if airspeed drops? Is it because it wants to maintain that low AOA (2-4 degrees according to the PHAK) with the relative airflow? If its AOA were to increase, such as not changing blade angle as airspeed drops, would drag increase causing the RPM to fall? And if airspeed is too high and AOA is too low, there's not enough drag to slow down the blades?

On takeoff, you want max thrust/power. By setting the blades to low pitch, you get max RPM because the blades take less of a bite out of the air. This also keeps blade AOA low which in turn reduces drag and allows RPM to build? Also, is max thrust in this case the result of the blades generating a lot of lift because of their high velocities from the higher RPM (versus thrust from moving larger chunks of air)?

Why is low RPM preferred in climbs/cruise? If you increase the blade pitch in these flight regimes, you get a smaller AOA with respect to wind which from my understanding so far reduces drag? But then doesn't the blade taking larger bites of air require more power anyways to maintain that RPM? Is it more efficient to give power to blades to move larger loads of air than it is to run at lower blade angles and higher RPM?

And lastly, with regards to blade AOA and relative wind, would a blade generate more lift if it had a higher AOA, but at the expense of additional drag on the blade which in turn requires more engine power? Is this drag induced drag because it's an airfoil?


texts: How well can a helicopter handle someone jumping onto it while taking off?

texts:
I see it a lot in movies, curious how say...an Robinson R44 would respond to a 200-pound man jumping and grabbing onto the skids while it's ~10ft off the ground and in the process of taking off??

Edit:
more specifically, how dramatic would the effect be?
with Hollywood physics, the chopper would stumble as if the hand of god lightly slapped its side?


texts: How did the USS Vincennes misidentify an Airbus aircraft?

texts:
Wikipedia indicates that the USS Vincennes misidentified Iran Air Flight 655:

  Crucially, Vincennes misidentified an Iran Air Airbus A300 civilian
  airliner, Iran Air Flight 655, as an attacking F-14 Tomcat fighter
  aircraft. The Iran Air Flight 655 was climbing at the time, and her
  IFF transponder was on the Mode III civilian code rather than on the
  purely military Mode II, as recorded by Vincennes's own shipboard
  Aegis Combat System. Vincennes fired two radar-guided missiles and
  shot down the Iranian civilian airliner over Iranian airspace in the
  Strait of Hormuz, killing all 290 passengers and crew on board.

Based on the narrative (and any other supportable information): Does the root cause of misidentification comprise:

Failure to follow procedure (Military / Civilian IFF, etc.)?
Equipment Failure?
Human factors (Fatigue)?

The questions are posed because this is the first of at least two Iranian-originating civilian flights that are misidentified by military personnel: I am wondering if there is a pattern, that can produce a lesson-learned (when the final report is published).


texts: What were the disadvantages of early prop driven blended-wing aircraft?

texts:
I've been researching the history of pre-jet aircraft and I've come across several famous, and not so famous, blended-wing aircraft. The idea seemed to show promise but never really caught on, even for a limited span of time or confluence of technological factors e.g. weight vs engine power etc.

Just to be clear, I'm not interest in flying wing and/or tailless aircraft whose early problems are well known, but rather those designs that have tails but have a fuselage shaped to produced a significant component of lift.

Just a few of the designs I've stumbled across:

Burnelli CBY-3

Cunliffe-Owen OA-1 (Burnelli license)

French de Monge 7.4

Soviet LK-1 a.k.a. Fanera-2

There are quite a few more I don't have handy web links for. Junkers did a couple that would probably qualify.

The large number of designs from all over the world show that the basic idea offered promise but all the designs eventually went no where despite being tried in many countries, economies and even political systems. That in turn seems strange because in the 1920s-early-1940s, lift seemed more important than speed for larger multiengine aircraft i.e. just getting a load airborne at all was worth quite a few other tradeoffs. As engines grew more powerful that tradeoff lessened but for at least 15-20 years a high lift design should have been more desirable than a high speed one for larger aircraft.

The failure of many different designers over the course of three decades to make the blended wing work suggest to me that the basic idea has some inherent disadvantage/s that outweighed any gains. Unfortunately, none of the resources I have consulted offer any clues to why the designs did not "take off."

I suspect the designs showed some rapid onset of stall of instabilty but that's just an uninformed hunch on my part.

Any clues?


texts: What material is used to make the interior sidewalls panels, ceiling as well as luggage bins in a commercial aircraft?

texts:
What material is use to make the interior sidewalls panels, ceiling as well as luggage bins? All these elements seems to be made of similar material.

What is the weight these cabin interior elements represent for a typical single aisle aircraft like the A320?


texts: What is the definition of “blade scatter” in gas turbine compressor dynamic balancing?

texts: Can someone help me define “blade scatter” gas turbine compressor dynamic balancing?


texts: Could anyone please help me with this Spatial Orientation bit and explain me its basics. I am having alot of confusion while attempting such questions. Any help would be much appreciated.


texts: Why isn't luggage that goes in the hold scanned as thoroughly as hand luggage?

texts:
I'm a regular international flyer, my hand luggage is always scanned, and despite my best efforts it often gets searched, either due to mistakes on my part, or security being extra cautious. On my most recent flight I estimate about 5-10% of my fellow passengers also had their hand luggage opened and searched by hand.

On the other hand, I have never had any issues with checked in luggage, I've never been pulled to one side and asked to explain anything, and as far as I can tell my luggage has never been searched (unless someone has picked the lock and then been very tidy in re-packing it)

So, my guess is that either 1) checked-in luggage isn't scanned as well as hand luggage, or 2) checked-in luggage is scanned by some super-hi-tech scanners that are infallible in identifying suspicious devices and never need checking by a person.

If the answer is option 1) then why doesn't checked-in luggage need such a thorough check? What's stopping a bad-guy putting a couple of kilos of something dodgy into his bag that brings down the aircraft over the Atlantic?

If the answer is option 2) then why can't the infallible super-hi-tech scanners be used on hand luggage too so no-one ever needs to be pulled over for a manual search?


texts: What aerodynamic improvements allow variable geometry wings to be omitted on modern fighter aircraft?

texts:
This sounds like a duplicate of Why aren't variable swept wings being used in newer military aircraft? of which there is at least one existing duplicate, but this question is different.

This question is specifically about what are the aerodynamic improvements that allow the variable geometry wings to be omitted? This seems to be an interesting question, as the aerodynamic design of certain fourth generation fighters such as the Su-27 and F-15, appear to be relatively straightforward. It is certainly not clear to a layperson what enables this.

For this particular question, issues such as stealth, improved engines performance, etc. are not relevant.


texts: What is the sweep angle of the Boeing 787's horizontal stabilizers?

texts: What is the sweep angle of the horizontal stabilizers on a Boeing 787 Dreamliner? Does it have to be equal to that of the wings, and how is it determined?


texts: Are there any safety mechanisms to prevent emergency slides deploying inside an aircraft?

texts: Does this kind of situation happen, or is this a test situation? Are there mechanisms to prevent inward deployment of emergency slides?


texts: What do tower controllers do when the airport is quiet?

texts:
Listening Hayward Executive Tower on LiveATC in the night, I noticed ATC can be quiet for periods of more than 30 minutes, and sometimes the communication is not even with an aircraft, but with a maintenance car.

What do ATC operators when the airport is quiet?


texts: Who was the air traffic controller voice?

texts:
I recall reading somewhere that the 'Air traffic controller' voice (you've heard it on TV on many occasions) started with one specific person and his mannerisms have been copied by many air traffic controllers since, particularly in the US.  The article mentioned his name but I can't find the article and can't remember his name.

What was the name of this chap?

Edit: I think that I read this in Fate Is The Hunter, an autobiography of a pilot working in the '30s to '60s.  Unfortunately I don't still have my copy so I can't look it up.


texts: How can pilots lacking instruments interpret vectors given by ATC?

texts:
This video is about European Air Transport flight 2939, a Boeing 737, which "lost all the instruments of the aircraft" shortly after takeoff.

  BCS2939: We are flying heading now, and we don't have even altitude and anything, so if you can, give vectors back to the field, please.
  Approach: Roger, Eurotrans 2939, turn right heading 360 and you can climb to 3000 feet.
  BCS2939: Right turn 360, 3000 feet. -pause- We are almost in visual, we don't even have altimeters.

Despite the lack of instruments the pilots manage to fly the headings given by Shannon Approach and land safely.

It seems that the instrument panels of the 737 are entirely digital:

I understand what vectors are:

  A vector is defined by a direction and magnitude. In aviation these represent your heading (the direction) and your speed (the magnitude). However, in normal aviation usage "vector" only refers to the heading and other nomenclature is used to assign/report speeds.

The 737's cockpit seems to lack an analog compass which would survive a power outage like this one:

How might the pilots have flown the headings given by ATC (as the visualisation shows they did) without a compass or altimeter?


texts: Could leading-edge dynamic stall occur for a tripped airfoil?

texts:
As far as I know leading-edge dynamic stall is characterized by the formation of a Leading edge vortex. This leading edge vortex forms due to the 'bursting' of the LSB (Laminar separation bubble). However, if the airfoil is tripped on the upper surface to make the boundary layer fully turbulent, does that suppress the leading edge vortex? if so, what will be the process leading to the dynamic stall in this case?
Your help is greatly appreciated.


texts: How does my Casio watch know the altitude in flight?

texts:
Wrist watches usually use the barometric pressure sensors they have to calculate the altitude. I have also confirmed this from the manual of my watch, which states that:

  The watch displays altitude values based on air pressure readings taken by a built-in pressure sensor.

Fine that's understood and makes sense and has always worked for me wherever I go.

Question

But then how does it know altitude during flight? The cabin of all commercial airliners are pressurized and hence the air pressure is not changing inside the cabin with the change in altitude (as happens for descent or ascent on ground). I know that even the aircraft itself uses pressure sensors for many calculations but those sensors are mostly usually on the Pitot tube and they sense the real outside pressure and not inside an pressurized cabin

I would also like to mention that yes the altitude reading it takes during a flight is not always close to what the real value is but still it does track the altitude difference when pressure inside the cabin remains same, how so?

Please note

That I didn't include the exact details of my watch because neither am I promoting any special model or a brand nor am I asking specifics of how a watch works, focus is on air pressure inside the cabin, not on watch. If needed I can provide the model and manual reference links.


texts: What are these on the F/A-18F's wingtips?

texts:
At 5:34, former TOPGUN instructor Cdr E. Vincent Aiello (the narrator) says

  Looks like you've got [I can't decipher] Xes.

What words was he speaking?
Is he identifying the missile-looking object marked by my red arrow below?


texts: Does the Ground Proximity Warning System (GPWS) see through clouds?

texts:
Or can it only detect terrain on a clear day or night? I’m mostly asking because of PIA268
I know GPWS is much more reliable in todays  time, and I’m unsure if the accident flight even had a GPWS system, but is it safe to say the chances of that scenario repeating, are minimal? Assuming the system is functioning properly and or the crew reacts properly to the warning.


texts: Is there a Flights API to get flight information months in advance?

texts:
I hope I am at the right place here. Asking this at Stackoverflow is not allowed (off topic)

I want to be able to plan flights in the future. (6-12 months ahead) I only know the Flights ID like LH2014. All I want is to get the departure/arrival airport and times.

Do you know of any API or fresh database?

If I am booking a flight 6 months in advance I will get all the information. So it should be possible. Or is this the data from the day I booked the flight?

I tried few APIs like flightaware or flightstats, but they can only deliver data for max. 72 hours in advance, not 6 months.


texts: If a SID chart says "GPS... required", can the plane use a different GNSS?

texts:
This US/FAA standard instrument departure says "Note: GPS or DME/DME/IRU required."

If the aircraft could tune into a different GNSS like GLONASS, could the pilot still legally fly the departure given that all other requirements were met?


texts: Is ADS-B required for flight under class B airspace but outside the Mode C veil?

texts: In the U.S., can a non-ADS-B equipped aircraft legally fly under class-B airspace extensions that are outside of the 30nm Mode-C Veil circle?


texts: There are plenty of videos of aircraft performing "steep" takeoffs, such as this one. When, if ever, is this kind of takeoff appropriate. What is the procedure?


texts: How do you sump fuel when it's raining outside?

texts: I've been taught to always sump the plane's fuel system before going flying to check for water / contamination / proper fuel grade. However, I've yet to go flying in rain. What's the proper procedure to drain fuel during rain? If I took the fuel cap off to dump the fuel back into the plane, I'd be worried about rainwater getting in the tanks.


texts: How is the direction chosen when landing a seaplane on water?

texts:
When using a runway, many factors are taken into account to choose the landing direction.

A lake can be used in almost any direction by seaplanes. I imagine wind is prevalent, but I guess other elements such as waves, form of the body of water surface, water flow should also be taken into account.

What are the elements taken into account when choosing the direction to land a seaplane onto a body of water, and how do thoses elements influence the direction?