texts: Why does the Boeing 777X have a flight deck similar to the 787 and not to the previous 777?

texts:
Almost 3 years ago I posted this question, Why didn't the A330neo and A320neo share the cockpit of the A350?, and short answers were:

  "it's what the market wanted"

  "there is a huge disadvantage to drastically changing the cockpit when going from an A320 to the A320 NEO or from a B737-300 to the B737-700, or 737 NG to 737 Max, and that has to do with the existing fleets."

Ok, I surely understood those ones, even if I specifically cited examples like complete transformations of B737 flight desk in 40 years history (explained as well in the second answer, thanks to sort of "compatibility mode" for old pilots).

I recently discover that new B777x has a flight deck almost equal to B787 (here a video) and not to previous generation B777 so argumentations explained so well in past answers are not suitable for this model.

Generally it seems that Boeing is "more courageous" in their updates than Airbus that seems more traditional (I am an Airbus fan but in this case, this seems the truth).

Anybody knows why B777X is so different from the original model, considering that efficiency seems increased of about 15%, something like difference between A330 and A330neo, or A320 and A320neo that share more things with original models?


texts: How does the "pendulum effect" affect biplanes?

texts:
A high wing airplane will correct itself (lateral stability) when disturbed because its c.g. is below the c.p. (looking at the plane from it's side), according to this forum post and the book below.

So my question is, how does this "pendulum effect" affect a biplane with two centres of pressure?


texts: What are the particular challenges faced when landing at Bristol airport (UK)?

texts:
Earlier this year I returned to Bristol on flight TOM-6633, and like most landings at Bristol the passengers found the experience physically immersive, attention grabbing, and at least a little exciting - enough for the odd gasp and finally some small amount of scattered cheers and claps.

In layman's terms - the approach was characterised by the plane apparently hitting a very large number of considerable bumps, while wagging the wings up and down/rolling from side to side all the way in (trying to avoid the bumps, maybe?). Finally we got near the tarmac and the plane touched down "decisively", enough to make all aboard thankful for buttock fat.

So what are the particular challenges typically facing a pilot coming into Bristol (UK) airport?

Are these challenges considered fun by those folks in the front seats with the fancy hats and scrambled egg (ie: Pilots)?


texts: Have any operational aircraft ever used over wing fuel tanks?

texts: We are most familiar with under wing fuel tanks, has any operational aircraft ever used over wing fuel tanks?


texts: When do carriers overhaul their flight schedules with flight re-numbering?

texts:
A (US domestic) carrier can obviously stop flying a flight, or some legs of that flight, for a host of reasons. But - occasionally it makes more significant changes, like re-numbering many flights, or changing a bunch of routes on offer etc.
My question is: Are there rules, or is there an established custom, regarding when this happens? Specifically, do operators always align these changes to the beginning of years, quarters, or months? Or do they just happen at arbitrary times and not even bunched together?
I'm interested in the period between 2000 and the present time.


texts: On old sectional charts, what was the purpose of the domestic ADIZ regions and what was the difference between a "Defense Area" and an "Open Area"?

texts:
Looking at an old US sectional chart from 1956, I noticed a few oddities around where Air Defense Identification Zones (ADIZs) were placed.
Compared to modern airspace where the US ADIZ is strictly off the coast and along the borders, there appear to have been additional land-based ADIZs dividing the country up into three parts. There was also a large ADIZ centered over Albuquerque. They also seem to have made a distinction between a "Defense Area" and an "Open Area".
What was the purpose of having an ADIZ inside the country? What's the difference between an "Open Area" and a "Defense Area"? And just what was so special about Albuquerque?


texts: How to start an approach in IMC loss of communication under IFR?

texts:
Suppose I lost my radio communication while en-route, I am following the cleared route to the last fix. I am flying the higher of my last assigned altitude and MEA. Then, I am holding at my last en-route fix and the filed expected arrival time is coming. In this case, how may I start to descent and commerce an approach? regarding which IAP to use and which IAF to head for, provided that the last en-route fix is none of IAFs in any IAPs and my last altitude is much higher than the minimums prescribed in the IAPs.

POST EDIT:

Transponder is on 7600
No VMC within the range of fuel
Destination airport is tower-controlled


texts:
I was recently answering this question and for some reason it made me think of this fairly famous aviation saying

  The three most useless things to a pilot are the altitude above you, runway behind you and fuel on the ground

Now, I get altitude above you - you may as well use some of it lest you meet a mountain. I also get fuel on the ground - if in any doubt fuel up before you go.

But I'm not sure I understand why "runway behind you" is useless in this context

Could someone explain?


texts: How do you calculate the vertical and horizontal tail volume if you have Vvbar and Vhbar?

texts:
I know the general formulas for calculating the horizontal and vertical tail volumes. Unfortunately, I only have Vvbar and Vhbar. I’ve checked through multiple textbooks and I don’t know why I can’t find an expression for Vvbar.

This is what I have.


texts:
Flight suits made of Nomex are flame retardant, which is important for flying some kinds of aircraft. However, they're not oil, dirt, or sweat retardant, so sooner or later they need a wash - a wash strong enough to remove all that muck.

Is there anything special you need to do to get them clean without losing their flame retardant quality?


texts: During VTOL landings, do Harrier pilots cut power before touching the ground?

texts: When vertically landing, do Harrier pilots cut power before they touch the ground?


texts: How likely are flares to be fire hazards once touching the ground?

texts:
According to the Wikipedia page of flares, flares create intense heat.

  A flare, also sometimes called a fusee, is a type of pyrotechnic that produces a brilliant light or intense heat without an explosion.

Could the flares launched by an aircraft as a defensive countermeasure against a heat-seeking missile cause a fire once they reach the ground?


texts: If my parachute fails to open, why should I aim for land rather than water?

texts:
I was watching these 'what if' parachute failure videos on YouTube and everywhere they say do not choose water over land. Why should we not choose water and what happens if we land in water?

One such video:


texts:
Who invented the canard wing?

I know that early planes like those built by Santos Dumont and the Voisin brothers used canard wings but who invented the canard wing?

Update

The plane built by Hiram Maxim and tested in 1894 had a canard wing for pitch control.

(source)

(source)

Hiram Maxim's plane

So, it is quite evident that this type of wing was not invented by the Wright brothers as some people believe.


texts: How do airlines handle communication/notification after an accident?

texts:
I'm a frequent subscriber of airport messaging services where you get notified of check-in queue times, delays in takeoff, ETA + 10 minutes, landed timestamp, baggage claim time and these kinds of information, but not life-dependent messages.

However, if something bad happens I assume I won't get a "Flight X crashed and burned" message on my cell, but most likely a "Contact the airline at 555-1212 for more information" or something similar.

What's the standard operating procedure in these cases?


texts:
Does a biplane need wing twist?

I understand wing twist is used to:

creat a soft/partial stall ( hopefully create a partial stall before a full stall)
balance the wing so a smaller horizontal tail is needed with less drag.

So if the top wing on a biplane is canted upward, in a mild stall, it will stall first, with the bottom wing still flying, creating a partial stall.

If the bottom is at a lower AOA, it's like having wing twist on 50% of the plane. Wouldn't this act like wing twist on a monoplane and reduce the total moment, therefore needing less of a horizontal tail, like the self balancing wings on modern gliders. Is this correct, at least conceptually?


texts: Which airplane has had the longest production run?

texts:
An earlier question received interesting answers on what airplanes have been in service the longest; this question asks about airplanes in production the longest.  By this, I mean from earliest production of the first variant, to the end of the production run of the latest variant.  Thus, the 737 would count from 1967 through the present, even though there have been plenty of variants along the way.

Regarding breaks in production... EDIT: any break in production less than a decade, doesn't rule out an aircraft.  Multiple breaks in production that total less than a decade of "down" time don't either. An aircraft that is essentially the same produced by somebody else is fine if both are generally regarded as being the same aircraft, even if the designation is different (i.e. the F4U was built by multiple manufacturers, but today everybody thinks of any of them as a Corsair).

Military, civilian, large & small, even including gliders & helos (if any have been in production long enough to be competitive) are all fair game.  We can mention balloons (as "aircraft," though not really "airplanes") as having been produced since before the Wright brothers, but that's not really what I have in mind here.  Edit: Nor is "oldest aircraft still in production," even though the answers tend to be similar since it looks like the aircraft mentioned there are still in production.  This question is about length of production run, even if it is complete.

So, longest production run... what do we have?


texts: What safety differences exist between carrying laptops in checked versus carry-on baggage?

texts:
Recent rumors say that the laptop ban might be extended to flights originating in Europe heading for the USA. This made me think, if laptops are not safe for carriage in the cabin how can they be safe for carriage in the belly of the aircraft? Say that a notebook is short wired such that if it turns on it ignites the battery. Storing the laptop in your carry on luggage would result in a cabin fire which can be put out by the cabin crew. But if this same laptop is in a checked-in bag there is no cabin crew near it. How is this risk mitigated? Or what are the procedures in case of a belly fire?

Furthermore if a laptop is carried inside a carry-on bag it can be switched-on at the security checkpoint to verify that it is a working laptop.


texts: How is d(Cl)/d(alpha)@stall and Cl increment to stall defined in Xrotor?

texts:
I hope there are some people around here with some experience in Xrotor than me. (Xrotor is:"XROTOR is an interactive program for the design and analysis of ducted and free-tip propellers and windmills." Found: here documentation is at the end of the site) For the Blade Section Properties, I need following:

========================================================================
1) Zero-lift alpha (deg):   0.00       7) Minimum Cd           : 0.0070
2) d(Cl)/d(alpha)       :  6.280       8) Cl at minimum Cd     : 0.150
3) d(Cl)/d(alpha)@stall :  0.100       9) d(Cd)/d(Cl**2)       : 0.0040
4) Maximum Cl           :  2.00       10) Reference Re number  : 2000000.
5) Minimum Cl           : -1.50       11) Re scaling exponent  : -0.2000
6) Cl increment to stall:  0.200      12) Cm                   : -0.100
                                      13) Mcrit                :  0.620
========================================================================

Now does anyone know how 3) d(Cl)/d(alpha)@stall and 6) Cl increment to stall is defined?

If I had to guess 3) is just the slop after Maximum Cl. But 6) which is also mentioned in the doc as "delta CL for the stall transition region" gives me some headache.

Any help is appreciated.

Cheers


texts:
When I speak of a co-worker, or a co-driver, I'm speaking of a mutual relationship and status (that's simply how the prefix co works in normal English) and I'm pretty sure it's what most people mean too.

When people speak about co-pilots on the other hand, it seems they might mean one of several things:

They are speaking of two pilots who happen to be working as part of the same crew, who are therefore co-pilots (which seems the most correct usage).
They mean a pilot who isn't the captain.
They mean the pilot monitoring rather than the pilot flying.
They think the aircraft has a pilot, and a kind of assistant pilot of lesser abilities known as a co-pilot.

(This last seems to be strangely prevalent, as if people imagine an airliner might be crewed by a fully-qualified professional and by some sort of assistant whose job is the aviation equivalent of holding the ladder, who looks forward to the day they'll be allowed to climb up it themselves.)

Weirdly, I have actually heard air crews use co-pilot in ambiguous ways, as though even they have given up trying to use the word with care; once I heard an announcement in one language that referred to the captain and the first officer, and then immediately afterwards in another to pilot and co-pilot.

Questions about co-pilot

It seems reasonable to say "my co-pilot" when speaking of a fellow crew member. However:

Does "the co-pilot" have any meaning (note the use of the definite article)?
Is co-pilot ever a rank?
Does the term appear in aviation regulations?
Is it used in crew management policies?
Is there indeed any standardised or formal use of it within the industry?


texts: How does the a movement of the cyclic control stick in a helicopter affect the swashplate?

texts: Yesterday I learned that the surface that the helicopter blades create while rotating is very similiar to a gyroscope, and thus gyroscopic precession works there as well. My question is, when the pilot moves the cyclic pitch controls forward, how does that affect the swashplate? Does it rise it in back and lower in front or does it rise on one side and lower on the other?


texts:
I have a friend that needs some info...

He has a Basic Med certification in hand.  He takes a drug that is on the DNI list however it is admissible with a SI (SSRI).  His GP doctor signed his Basic Med form.  His GP doctor obviously knows the drug he is on and knows he is fully functional on the drug.  His GP doctor knows the drug is on the DNI list.

Given that background...

Would he have any possible insurance issues (renters or owners) if he were to ever get into an incident?  Could the insurance company deny a claim if he takes the drug even with a doctor's approval but WITHOUT the SI?

Thoughts?


texts: What are the weather requirements to log an instrument approach?

texts:
So let's assume that I'm the sole manipulator of the flight controls in an aircraft in which I'm rated and that I fly an instrument approach.

What weather does the FAA require (assuming that I'm not wearing a view limiting device) in order to log the approach for currency requirements?  For instance, if I am cleared for an ILS in visual conditions, can I log it?  What if I start the approach in the clouds and break out at 1,500 ft and continue the approach?  1,000 ft?  Before/after the outer marker?  150 feet above minimums?  I think that you get the idea....


texts: Why can't jet engines operate with supersonic air and how do they slow it down?

texts:
Typically jets cannot operate when intake airflow is supersonic relative to the engine. Why is this so? Also, why are scramjets able to use supersonic air?

To slow down the air to subsonic speeds, the air passes through a shockwave (if I understand correctly). How does this slow down the air?


texts: Do seaplanes need to get clearance for takeoff? Do they have ATC? How do seaplanes get clearance to takeoff?


texts:
I am a CFII who has a commercial multi-engine certificate. My friend was building time in a BE-58 Baron (multi-engine) for his MEI. He asked me to tag along (right seat)since he was going to file IFR and fly in some IMC.
Since he is logging the PIC, and all I did was tune in the freqs and programmed the avionics, can I log this as total time?
Also since we flew in IMC can I log the “Actual Inst” time?


texts: Why is bleed air taken from some stage of the compressor used for de-icing? Why not e.g. exhaust gas?

texts:
In the answers to this question, it is said that

  The de-icing system on most turbine aircraft (including MD-82 involved in that accident) uses bleed air from the engines, that is it extracts some air from behind the (low pressure stage of the) compressor. This air is therefore not ejected from the nozzle and not producing thrust, so the thrust is reduced.

My question is:

Why is bleed air taken from some stage of the compressor used? Why not e.g. exhaust gas?

For de-icing, the temperature of the used medium must be above 0°C (melting ice), while the environmental temperature usually is far below.
So the engine has to invest energy to generate bleed air with reasonable temperature, the air cools down to still >0°C during de-icing, and is then vented out to the environment.
There, it expands and cools down far below the environmental temperature.
This expansion means that energy is wasted, and also, when the bleed air is cooled down / expanded before inserting it into the de-icing system (I don't know if this is done), energy would be lost.
In addition, air/pressure is lost in the compressor stage, which makes the combustion less effective. (Again, I don't know how much air is taken, and how big the effect is)

On the other side, the exhaust gas of the engine is very hot due the combustion and could be used without the need of extra compression. So, using some exhaust gas, one would not waste so much energy. If it's too dirty, heat exchangers could be used to heat fresh air.

I would think of this reasons

Bleed air is anyway used for many purposes in an aircraft, so this is more economic than a completely separated system
De-icing is not used for long time during flight, so again no need for a dedicated system

EDIT:

I'd like to expand the question to explain what makes me curious. In the comment, the correctness of this sentence is challenged:

  There, it expands and cools down far below the environmental temperature.

This is a simple thermodynamic process. The air is compressed adiabatically, i.e. without adding heat to it. The heat comes from the thermal energy of the air, now also compressed to a lower volume.
De-icing cools down the air, and when releasing the air to the environment, it expands to the orignal pressure. As thermal energy has been removed during de-icing, the temperature drops below environmental temperature.

Here is the math behind:

The relation of pressure and temperature in this case is:

$$ p_1^{1-\gamma}\cdot T_1^\gamma=p_2^{1-\gamma}\cdot T_2^\gamma\qquad \gamma
\approx 1.4$$

Let's assume a pilot switches on de-icing during flight at 11km altitude. There, environmental pressure is 0.25bar (atmospheres) and temperature is -50°C (223K). It was also said here in the answers that it's possible that the bleed air has about 200°C (473K).
The formula now gives a bleed air pressure of 3.47 bar, so a pressure ratio of about 14. The air is now cooled down while the pressure is maintained by the engine. I assume de-icing will be effective for bleed air temperatures above 0°C. So if the air is released at this temperature, the temperature will fall down to -144°C (128K). Another number: If releasing at 100°C, the temperature will drop to -97°C (175K).

(Of course, the air will mix with the environmental air immediately)

In principle, one can play with the numbers, increase/decrease altitude / temperatures and discuss how adiabatically this (de)compression processes are.

Anyway, this is a big air conditioner, using the thermal energy for de-icing and wasting the cooled air. If one only needs hot air, something coming from the exhaust system would always be more efficient.

This is not really efficient. May be the bleed air behind the de-icing system can still be used for other purposes, as it still has the pressure?


texts: Do F-4 Phantom II pilots actually fold the wings?

texts: In flight simulator X-Plane 8.15, the F-4 Phantom 2 can fold the tip of its wings (well, variable sweep). Is that useful? Why would a pilot fold the wing? To reduce lift for short landing?


texts: Why are airplanes described as the safest method of transportation?

texts:
I will have my first flight tomorrow. It is my first time that I get into an airplane, and by the time am  writing this post, I am feeling anxious and stressed a lot. I even don't talk to anyone as it is the last day of my life and need to live it alone. I read that this is called "fear of flight" or "phobia of airplanes".

I read online on all related sites, that the airplanes are the safest transportation mode. I could die with a car accident while I am getting to airport 20 times more than be killed in an airplane crash.

All sites said that I should understand more about airplanes, and that would release the tension and make me better.

I am thinking to cancel the flight and the 330$ will go through the wind as we say in my country, and not be refunded. I read a lot of things but all are technical, and I didn't understand any single word, especially that I am a person that don't have any mechanical or technical background to understand it.

My doctor told me to start taking "Xanax" and that would help me be fine on my less than 2 hours flight (most of it is over the sea that's why I am more anxious).

Why are airplanes the safest method of transportation? Why aren't ships the safest? Because in 3 years I didn't hear of an airplane that sank.


texts: What is a 'deep stall' and how can pilots recover from it?

texts:
West Caribbean Airways Flight 708 which crashed in 2005, fell victim when their plane encountered a deep-stall. From my understanding, only certain planes can 'deep-stall'

How can pilots recover their plane to recover from a deep stall?


texts: What does the future of the weather radars look like?

texts:
Planes had weather radars for a long time (Dassault Falcon and Learjet35A) which was useful since you either had to ask ATC, listen the ATIS frequency or ask the flight advisory before flight planning in order to learn the weather.

But we are living at a time of two way transponder communications and more and more of the world (At least the USA) are employing more weather stations and satellites are continously monitoring the world which makes the weather information more and more accessible and in flight Wi-Fi finally arrived!

So. are there plans about sending weather information through two way transponders in the future? Will this hamper the importance of weather radars?


texts: Does a full set of legible structural engineering drawings for the Hughes H-4 Hercules still exist?

texts: I am not looking for unreadable images or pictures of images, but a fully legible copy or print.


texts: Can we use ECI coordinates for an airplane?

texts: It is taught for navigation systems (like an airplane) on Earth we us ECEF (earth-centered, earth-fixed) and for space systems (like a satellite) we use ECI (earth-centered inertial). But why is ECEF exclusively used for navigation vehicles on Earth and ECI is exclusively used for satellites and spacecraft in space?  Why can't we use ECI for an airplane to observed another perspective?


texts: What is the round thing on the tip of an MD-90 wing?

texts:
I like to pretend I know about airplanes, but have always wondered what the round things on the tip of MD-90 wings are. Here is an image of what I am talking about:

To be clear, my question is what the round, hole-like item is in this photo. It is on the trailing edge of the wing facing backwards. My current best guess is that it is the hole that the smoke comes out of when Delta is using the planes for sky-writing and doing other cool loop-de-loop type tricks. I have yet to see the smoke come out...


texts: Is it legal to fly the localizer approach when cleared for the ILS?

texts:
Most ILS approaches include localizer minimums that can be used if the glideslope transmitter or receiver fails.  For example:

In this case, to fly the ILS you would intercept the glideslope just before PRAIZ and fly the 3 degree glideslope down to minimums.

If we were cleared for the ILS approach, but we instead wanted to ignore the glideslope and fly the LOC only approach1 (for whatever reason:  training, practice, etc.), could we do that without specific ATC approval since it is on the same chart and says "ILS or LOC"?

1 We could fly the LOC only approach by crossing PRAIZ at 2,200 ft. and then descend at an "optimum" rate until leveling off at the MDA of 520 ft.


texts: How to adjust the center of gravity of an aircraft if not level when being weighed?

texts: how do you adjust the center of gravity when weighing an aircraft in not-leveled position using platform scales under the nose and the main gears, and dropping a plumb bob to mark the gears locations.


texts: Can pop-out floats be installed post-manufacture on all helicopters?

texts:
I have seen in many helicopters pop-out floats installed.

Are they the optional, or do they come pre-installed with every helicopter?


texts: List of airlines and aircraft types at Copenhagen Airport (CPH)

texts:
Is there a website with a list of all the airlines that fly to Copenhagen Airport (CPH), and with what aircraft types they fly to Copenhagen?

I have found a list of airlines at the website from Copenhagen Airport, but no cargo airlines are mentioned there, and also no aircraft types. I have started with that list and typing over the aircraft types from the complete fleet from Wikipedia or the website of the airline itself, and then looking at Flightradar 24 which aircraft of the fleet is actually used to fly to and from CPH, but it takes a really long time and due to summer/winter schedules I will probably miss out on some.

Or if anyone has tips for a faster (and more accurate) solution if such a list does not exist...


texts: What does "1%" mean in ICAO Annex 14 § 3.9.9 (longitudinal slope changes)?

texts:
— 1 per cent per 30 m (minimum radius of curvature of 3 000 m) where the code letter is C, D, E or F; and
  — 1 per cent per 25 m (minimum radius of curvature of 2 500 m) where the code letter is A or B.

Can someone explain what "1% per 30 m" means?

Does it mean 0.3 m of elevation difference for every 30 meters? Or 1/100 per 30 m?


texts: What happens when I tell ATC to "mark the tape"?

texts:
You can find anecdotal mention of this phrase among pilots you may talk to as well as postings on various forums.  The idea conveyed is that telling a controller to "mark the tape" means they will make take some action to note the current time for the audio recording of his seat, which can then be referred back to by someone.  As many anecdotes you can find about this, you'll find just as many saying this phrase is essentially an old wives tale, and means absolutely nothing.

Given a situation with a controller that I'd like to bring to the attention of his superiors, or perhaps just with him over the phone, does using the phrase "mark the tape" do anything?  If it does nothing, what is the proper procedure I should use to review something with a controller or their supervisor (e.g. noting time and frequency, asking for a phone number)?


texts: Is there a maximal time to pass a type rating?

texts:
Let's say you begin a type rating for a long haul carrier (e.g. A350 or B787) at day 1. After few days, your training stops due to external causes (airline paying your training bankrupt, all aircraft are grounded in your area due to Eyjafjöll ashes, or even in a larger area due to a pandemic such a covid19,...).

Is there a time limit to resume your training? If so, what is the maximal allowed time between the first day of your type rating training and the day you pass it?

This question can be restricted to A350 and B787 under FAA and EASA regulations if needed.


texts: What features enable the Su-25 Frogfoot to operate with such a wide variety of fuels?

texts:
It is widely attested* that the Su-25 Frogfoot's engines (the Turmansky R-95Sh and later the R-195) were designed to function using a wide variety of fuels, including diesel, gasoline, petrol, kerosene and avgas.

For a rough-field front-line attack aircraft, the ability to load it with whatever was at hand, even tank fuel, would be very useful.

It's not a feature I've read about anywhere else. The question is, what specific engine modifications allow this level of fuel-tolerance in comparison with, for example, the T-34 which powers the A-10, an aircraft designed for a similar role.

 * for example miltaryfactory.com lowflying.net

 Su-25 Grach  (NATO reporting name: Frogfoot)

(Previous questions asked whether diesel engine aircraft can run on car diesel (yes) and if you could safely run a 777 on diesel (no).)


texts: Would an F-15 or similar stand in be able to continue flight at high speed if it lost its canopy?

texts:
Let's say for whatever reason, miscued ejection system perhaps, a jet in flight at exactly mach 1 blew its canopy but did not eject the pilot.  And we can assume the altitude is fairly low (to exclude the attendant freezing/suffocation that would ensue).

My friend and I have been arguing about this.  He insists that it would result in catastrophic damage to the jet due to a sudden lack of aerodynamic stability and that the pilot would be grievously harmed or killed.

For my own part, I'm just not so sure.  It seems to me that if said pilot was wearing a JHMC or some helmet with visor that he'd have plenty of time to react and set the aircraft safely down.  And could probably do 400 knots comfortably on his way home to complain about the faulty ejection.

And I figured a jet is so very large and aerodynamic over its entire body, without the canopy it'd be less so, but still not so badly that the thing would be torn to pieces as a result, right?

The only similar story I could find was of an F-14 that lost its canopy, but the pilot only mentioned going 320 knots and it not being as loud as he expected.

So mach 1 is a key part of this question, I think.  I can't find a reasonable answer to settle our dispute, someone please help!  I really want to settle this.  Thanks in advance.


texts: What are the main differences between Flares and Chaff?

texts: Over the years I've heard the two used almost interchangeably but after watching some videos it would seem that they each have specific and particular functions.


texts: What are the areas marked in green around the taxiways?

texts:
In the photos for this AvHerald article you can see areas marked in green with yellow stripes around the taxiways.

The entire maneuvering area appears to be solid concrete. The green painted areas are outside of the taxiway edge markings and the vehicle roadway markings. Is this green area intended to be a buffer zone to account for wings sticking out past the taxiway edges? Or is it just there to help show where the taxiway edges are? Should an aircraft's wingtips remain within the taxiway or can they hang over the edge?


texts: Can the fluid from one hydraulic circuit go to another one (voluntarily or not) in flight?

texts:
Given the following facts for airliners:

Fuel can be transferred in flight from one tank to another
Hydraulic energy can be transferred without fluid transfer from one circuit to another in flight using a PTU
Many hydraulic components are fed by several hydraulic circuits and thus may use fluid from several hydraulic circuits simultaneously

Can hydraulic fluid go from one circuit to another while in flight?


texts: What is a flameout and how does it occur?

texts: I often hear the word "flameout". What is this and how does it occur?


texts: Why would a glider have water ballast? If it is trying to stay aloft without an engine, wouldn't it be better to be as light as possible?

texts:
So I was looking at the description of a ASW 27 B glider and ran across this statement:

  Two water tanks in the wing plus a further 35 liter tank in the
  fuselage enable the ASW 27 B to carry more water ballast than any
  other 15 m glider and also give it the widest range of wing loadings

If a glider is trying to stay aloft as long as possible, wouldn't it be better to be light?  Why would you add ballast and be able to dump it?


texts: What is the purpose of this span wise "false spar" on Affordaplane wings?

texts: This is the wing of an Affordaplane Ultralight,what is the use of those spanwise foam boards between the foam ribs,I know it's not for aesthetics.


texts: Does waverider have much lower drag than Sears Haack body?

texts:
I tried to calculate drag for hyper velocity project using this paper for Sears Haack revolution body. Some parameters:

Diameter: 160mm (round number for simulating 155mm projectile)

Fineness ratio: 13.2, which means projectile's length is 2112mm

From the paper, the assumed wing area $S$ is

$$0.077 \cdot l^2 = 0.077 \cdot (2.112)^2 = 0.3435 \ [m^2]$$

From the Figure 15 in the paper, the total Cd at 2km/s is about 0.004

So total drag at sea level
$$D = 0.5 \cdot v^2 \cdot \rho \cdot S \cdot C_D$$

$$D = 0.5 \cdot 2000^2 \cdot 1.23 \cdot 0.3435 \cdot 0.004 = 3380 \ [N]$$

From the paper, the volume $V$ of the projectile is

$$V = 0.002655 \cdot l^3 = 0.025 \ [m^3]$$
Assume it is filled with aluminum, then the mass $m$ is about
$$ 0.025 \cdot 3000 = 75 \ [kg]$$

So the drag is about 4.5g.

On the other hand, there is an empirical formula for hypersonic lift to drag ratio is:

$$\frac{L}{D} = \frac{4 \cdot (M + 3)}{M} = \frac{4 \cdot (6 + 3)}{6} = 6$$

It seems that if the projectile is shaped as a good waverider then drag can be as low as 1/6 of its weight, assuming the waverider is the best shape for hypersonic lift to drag ratio.

There is of course the problem about scaling where mass is increased at cubed speed, while area only increases at squared speed. While I don't have an complete computational model of waverider to compare directly with SH body, but it seems at the first glance, the waverider can get much lower drag than even the most aerodynamic shape, 1/6g vs 4.5g.

So is it true that the waverider has much lower drag than a SH body?


texts: Just how do the underbanking and overbanking tendencies work?

texts:
I understand that most GA airplanes and gliders exhibit an underbanking tendency at low bank angles and an overbanking tendency at high bank angles.

According to the Airplane Flying Handbook, chapter 3, page 3-11, if the aircraft is in steady, coordinated flight at a bank angle less than about 20 degrees, then

  This shallow bank is such that the inherent lateral stability of the airplane slowly levels the wings unless aileron pressure in the desired direction of bank is held by the pilot to maintain the bank angle.

On the other hand, if the aircraft is in steady, coordinated flight at a bank angle greater than about 45 degrees, then

  The  airplane  continues  in the direction of the bank even with neutral flight controls  unless  the  pilot  provides  opposite  flight  control aileron pressure to prevent the airplane from overbanking.

What causes these underbanking and overbanking tendencies, exactly? How do they work?

I know that when an aircraft is in a coordinated turn, the situation as experienced by the aircraft is almost identical to straight flight. As far as I know, the only significant differences are the following:

The outside wing will see a greater airspeed than the inside wing, which will mean:

The outside wing will produce more lift than the inside wing, producing a rolling moment to the inside.
The outside wing will also produce more drag than the inside wing, producing a yawing moment to the outside.
On the other hand, the outside wing will also see a shallower angle of attack than the inside wing, which will partially negate both of the above effects. I'm guessing that the lift effect will be negated more strongly than the drag effect.

The nose will see relative wind from the inside of the turn (which will have no significant effect); and the tail will see relative wind from the outside of the turn, which will produce a yawing moment to the outside.
Since the rudder is deflected towards the inside of the turn, the vertical stabilizer will produce a rolling moment to the outside.

So my questions are:

Is my understanding of the rolling and yawing forces in turning flight correct? Are there any significant effects I've missed? And how large is each of these effects—which ones are the big ones, and which ones are insignificant? And most of all, how come there's an underbanking tendency in shallow turns, but an overbanking tendency in steep turns?


texts: What is the fuel burn of the APU on the CRJ900?

texts: Looking for a reference from an FCOM, AFM or other manual for the fuel consumption per hour in pounds or kilos of the Honeywell RE 200 APU on the CRJ900.


texts: When was the pitot-based ASI first used on aircraft?

texts: The pitot was first invented well before aircraft, yet early aircraft lacked an airspeed indicator (ASI). What aircraft first had a pitot-based ASI, and when?


texts:
When at a towered airport and instructed to make "left pattern for runway 3," am I supposed to wait for the base leg turn until tower clears me for landing?  This seems to be the norm, but I can't find anything in the FAR/AIM to indicate what is acceptable.

Related: I often get confused when in the downwind pattern and I hear something like this: "123X, tower, you are #2 for runway 3, following a Cessna on final."  Does this mean I should turn base and follow the Cessna?

I know the correct answer is to ask ATC to clarify, but it would be ideal if this were spelled out in the AIM.


texts: What was the forensic process underlying the recent news regarding MH370 debris?

texts:
On or about July 30, 2015, the initial news could have been worded like: "debris appears to have come from a Boeing 777". As the story evolved, additional details emerged such as the wreckage being part of a 777 flaperon, before being decisively announced.

My question is: what was the forensic/investigative process which would have produced the initial speculative-sounding announcement associating the debris to a 777, before ultimately becoming the more definitive statement?

To put it another way: what steps had investigators taken up to the point of each announcement, and how was the debris recognized very early on as part of a 777 without actually being confirmed as such? Is it investigator experience? If initial identification was made by part numbers, why would there have been any doubt in the announcement?


texts: Is the gas velocity of a jet engine relative to the engine speed or is it absolute?

texts:
Let's say we are testing a jet engine on the ground by keeping it still. We measure the inlet and outlet velocity of the gas at a specific operation point. Let's assume that we attach this engine on a aircraft that is of course moving. In a random time the operation point is the same as before. If we measure the absolute inlet and outlet velocities are the same as before or only the relative ones(aircraft velocity+gas velocity) are the same?

And one more similar question.
In the case of the engine attached to the aircraft all the fuel energy that can be used is transformed into changes of the kinetic energy of both the aircraft and the air passing through the engine.Right?
In the first case of the test, the kinetic energy of the engine isn't changing, so all the used fuel energy is changing the gas kinetic energy, so in this case the difference in the kinetic energy of the gas is greater. Does this makes sense since we talk for the same operation point?

To conclude, is the thrust the same regardless if the jet engine is moving or not?


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

texts: Where do I find the Weight Variants (WV) of an Airbus aircraft?


texts: Can anyone explain what a fused track is from the perspective of radar?


texts: What is the purpose of these "antennas" on the aileron and winglet (A320 Neo)


texts: How is the static pressure in the pitot static system reconciled when there are two outside static pressure ports?

texts:
On airplanes where there are two static pressure sources (ports) on each side of the fuselage what is the result of the static pressure as compared to aircraft with a single port. (I'm not talking about the alternate static port which is usually inside away from freezing weather).

For example, from the diagrams I've looked at it appears that the dual static ports are connected to a common line such that the pressures from each port are averaged out, such that if one port has 14 psi and the other 10 psi the result will be 12 psi. Is this how it works?

Another example to help illustrate my question, imagine an aircraft with two static ports on each side exactly symmetrically opposed is in a forward slip attitude, (ignore ram air pressure for this example), does the static pressure from each side when mixed together cancel out the error caused by the slip attitude as compared to an aircraft with a single static port in the same attitude? Does dual symmetrical static ports correct error of a slip to give you the actual static pressure as if the aircraft was flying perfectly coordinated? (Again, this question is just about the static pressure, not ram air).

If anyone has a more concise way to ask this question please chime in.


texts: Does an RMI show true or magnetic north?

texts: Does the compass card of a Radio Magnetic Indicator (RMI) point to true north or magnetic north ?


texts: Can a bullet hit make the cockpit door open?

texts:
If there is a hijack situation and the terrorist guy shoots at the cockpit door to go inside, will that work?

Are the cockpit door locks in commercial planes like 737s etc good enough to handle a bullet shot?


texts: How does an Airbus aircraft connect to the Internet?

texts: I would like to understand better where (physically in the aircraft) and how the Internet connection is received on an Airbus aircraft, in particular in an Airbus A380, and then how this system is linked to the access points that serve the passengers. What path(s) bring(s) the connection from the antenna to the access points that make it available to the passengers?


texts: Is there independent evidence that the Wright brothers celebrated Roosvelt's election in 1904 by a flight of over 5 minutes?

texts:
In a letter addressed to Octave Chanute, Wilbur Wright made the following statement:

Wilbur Wright, “Letter to Octave Chanute”, Dayton, November 15, 1904.
“On the 9th we went out to celebrate Roosevelt’s election by a long
flight and went around four times in 5 min. 4 sec. We unfortunately
failed to set the recording anemometer and so did not get a measure of
distance, but it was evidently a little over three miles. The trouble
in righting the machine after swinging a short circle is evidently
corrected. The machine landed without any injury and was put back on
the track for another trial, but the wind had been working more and
more to the south and we were unable to get another start.”

I guess, there should have been some witnesses, journalists, etc., present. Well then, who really saw the flight?


texts: How to sign hours on Logbook if doing aerial work in right seat on single pilot aeroplane?

texts: Recently I got an offer to work during the incoming summer as survey pilot, but since I do not have the required hours for insurance I can not be the PIC on left seat. So they proposed to be on the right seat until getting enough experience and then switch on. Can I sign those hours on the right if the aircraft is certify for single pilot operation? How?


texts:
I'm looking at the takeoff mins and DPs for Reno/Stead (RTS.)  It lists takeoff mins for Cat A and B, Cat C and D NA:

  TAKEOFF MINIMUMS: CAT A,B only, CAT C,D NA. Rwys 8,14,  1300-2 or std.
  with a min. climb of 400' per  NM to 6500.  Rwy 26,  1900-2 or std.
  with a min. climb  of 410' per NM to 7200.  Rwy 32,  2300-2 or std.
  with a  min. climb of 420' per NM to 7200.
  (Source)

What are the departure categories?  I can't find any mention of them in the instrument flying handbook.


texts: Which (if any) is the "most major" airport / field / strip on Antarctica?

texts:
Which airport (/field, /strip, /skiway) is the "biggest", "most supported" on Antarctica?

So,

has the most permanent staff (do any?)
has the most runway facilities such as say runway lights, markings, length, aircraft weight possible, surfaced (are any?), etc?
has the most or any fueling facilities?
the most or any ground support facilities? repair facilities?
is opened all or at least the most months of the year?

What's the state of the "best" airport (or analogue) in Antarctica?


texts: What is the minimum separation for navaids to work properly without interfering?

texts: What is the minimum separation between navaids (for VORs/DMEs and NDBs) for them to work without interfering, by regulation and by functionality?


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

texts:
I am reading in the FAA-H-8083-32 Aviation Maintenance Technician Handbook-Powerplant book posted on the FAA site that there are engine valves with different types of head shapes, e.g. mushroom, tulip, semi tulip (image taken from flight-mechanic.com).

What is the reason for these shapes?


texts: Angle of attack difference between outer wing and inner wing during a descending turn and climbing turn

texts:
I understand that during an ascending or descending turn the angles of attack of the inner wing and outer wing are different.

However, I don't understand why then ascending and turning, the outer wing has greater AOA than the inner wing but during descending and turning, the inner wing has greater AOA than the outer wing.

Clarification:
My confusion is that, for example, if the AOA is greater for the outer wing, then the AOA should always be greater for the outer wing regardless the airplane is climbing or descending.


texts: What type of visa do pilots who fly from one country to another need?

texts: I am little curious about international travel. I would like to know what type of visa allows pilots and cabin crews to fly from one country to another? I mean suppose I am pilot of Japan airline and I have trip a for Netherlands. How could I enter to the Netherlands with Japanese citizenship?


texts: How can I customize my training to become a flight instructor?

texts:
I plan on starting my flight training soon at the age of 41, but I don't want to stop at PPL and simply fly for fun: I want to ultimately be a CFI.

With this goal in mind, my question is what recommendations can my fellow aviation enthusiasts and experts give me in the planning I should do for my aviation education? Is there a specific type of facility to select for training, a progression of obtaining certificates and ratings I should follow, etc.?


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

texts:
Background: An AC-130 is a military aircraft that has a cannon that fires out the side of its fuselage.

If an AC-130 (or similar aircraft) is traveling in straight, level flight at a constant rate of speed calculating gun lead is straightforward.  For example if the plane is traveling forward at 100 meters per second, the target is 1000 meters to the side and its cannon shell travels at 1000 meters per second simply fire 1 second or 100 meters early to score a hit.

However what if the AC-130 is traveling in a circular orbit at 100 meters per second around its target instead of beside the target?  I'm not sure how to calculate gun lead in that circumstance.

Hopefully the image I attached below will help this make sense.  Thanks so much in advance for any input!


texts: Do fighter jets have a traditional inverted fuel system?

texts:
Common solutions for aerobatic piston singles is to have either header tanks (for wing tanks, as I understand it) or flop tubes (for fuselage tanks).
Do fuel systems in a fighter jet work on the same principles? Or are they somehow smarter to allow more erratic maneuvers?


texts: How does Air Traffic Control know a flight's route and destination?

texts:
I am trying to find out in layman's terms how does ATC determine the direction a flight has to take after takeoff, or when should it start descending for the destination airport. I understand it has to do with the flight plan but Googling revealed lot of technical stuff that I couldn't understand. In my limited experience of listening to LiveATC and YouTube video, ATC never inquired about the destination - it felt like they already knew.

Is destination information always available on the screen to ATC or does the flight crew request changes based on their flight plan? How does it work when you cross international boundaries? Is the same flight plan available to ATC in all the countries the flight will be flying through?

For example, a flight taking off from SFO could be northbound towards Seattle or southbound to LA or eastbound. ATC has to make room for the proper direction of the flight and hence needs to know the destination.

To complicate matters, I have seen flights taking different routes while the destination is same e.g. one SFO-FRA flight hugged the west coast (magnificent views of the coastline) up to Canada before making a right turn, whereas other times - but with the same flight number - it kind of crosses the continental United States diagonally. So I feel it's not just about the destination, there are other factors involved.


texts: Carrier frequency and transmit power of a commercial aircraft

texts:
I have a few questions on the radio comms. aspects of commercial aircrafts.

At what (central) frequency does an aircraft communicate with a control tower? Is the communication over one frequency only? How much is the transmit power of the antenna per channel on both uplink and downlink? Is it per hertz?

Also please correct me if I’m wrong: From my readings, aircraft-airport communications is analog only, correct?


texts: How does passenger unloading order prevent plane tipping?

texts:
This answer to the question about an emergency landing very early in a trans-continental flight indicated that the fuel in the aft auxiliary tanks could cause the plane to tip on its tail if the passengers weren't unloaded carefully. The cabin crew seems to have kept everyone calm and orderly, and they deplaned with no further incident.

My question is how did the orderly disembarkation prevent the plane from tipping?

These are the thoughts that ran through my head as I read the story:

Were the pilots busy moving fuel out of those aft tanks while the pax were deplaning?

If so would they have started the rebalancing as soon as the firefighters cleared the plane to move?
Would that have taken the hour it took to get the plane to a gate for them to shift all the fuel?

What else would be involved?
If the fuel in the tail would cause the plane to tip, unloading the pax slowly would still leave it with an aft CG, and it would still tip once the critical number of people were off.


texts: Which airlines allow you to gain hours with them by paying them

texts: As a fresh grduated pilot is there any airline that you can pay them to fly with them without a salary just to build hours?


texts: How will a prolonged series of steep turns produce a stall in subsequent level flight?

texts:
In Stick and Rudder, the author warns pilots against the unreliability of judging airspeed and hence “buoyancy” — his term for how far the airplane is from aerodynamic stall — by throttle position, engine noise, and nose attitude.

  Perhaps the most deceptive of these factors is g load. When an airplane, flying at a certain speed, goes into a turn and loads itself down with g load it assumes larger Angle of Attack and this gets closer to the stall. That has been described earlier in this book. But it isn’t the whole story. At the larger Angle of Attack, the wings have more drag, and thus the airplane will slow up, unless the throttle is opened wider. The airplane assumes a still higher Angle of Attack and gets still closer to the stall! Few pilots realize how strong and dangerous this effect is.

Langewiesche, Wolfgang. “The Flying Instinct.” In Stick and Rudder: An Explanation of the Art of Flying, 58. New York: McGraw-Hill, Inc., 1944.

He then gives a surprising example.

  The average small airplane, fully loaded and with its throttle set at cruising, is actually unable to hold indefinitely any turn banked much more than 45 degrees! The effect just described will slow it down gradually, as it circles, so that the pilot’s stick comes farther and farther back; until finally, after perhaps twenty turns have been completed, it will stall: stall, mark you, out of level flight with cruising throttle!

ibid.

Why doesn’t nosing over to leave the steep turns for straight-and-level attitude with open throttle produce sufficient airspeed to avoid the stall?


texts: How is close formation flying possible with things like thermals and turbulence?

texts:
This weekend the Blue Angels came to town. The weather was less than perfect. A quick look at SkyVector during their show indicated there was an active AIRMET for moderate turbulence.

This made me think about the effects of weather (namely phenomena that can change affect the physical location of an aircraft in flight like turbulence and thermals) on planes flying in extremely close formation.

How is close formation flying possible with conditions like this?
Is the net effect of this type of weather minimized for planes of this type?


texts: Components on engines, are they removed or blanked out?

texts:
As a follow up to why doesn't the A380 use outboard thrust reversers, if a component is not used in an engine, is it completely removed (hardware, wiring etc etc) or is it just made inoperative?

In the case of the A380 wouldn't it make it more difficult to maintain and handle 2 engines which are the same, but with different accessories installed?

Wouldn't it be risky as there might be human error factors whilst servicing or installing the thrust reversers?


texts: What is some of this extra "stuff" on jet engines?

texts:
At the risk of sounding too broad, I want to better understand the complications of jet engines. This time, I'm asking about extra "stuff", which unfortunately I have no better name for since I don't know what it is.

I'm familiar with the basic cycle of jets. Compressor stages draw in air and pressurize it, combustion heats and expands the air, and turbine stages extract some torque from the jet to drive the engine.

It all seems so simple. However, then I see pictures like these:

It's a modern turbofan. What is all that extra stuff? Can it really all be fuel and air lines? I'm especially scratching my head because the basic design has only a handful of moving parts (the stages/blades) all driven by the turbine and its shaft, so I can't imagine those are mostly hydraulic or electric lines either.

I found a simpler example here (Tumansky RD-10):

It is a turbojet and much older.


texts: Do flights of a specific callsign always depart and arrive at the same airports?

texts:
I've been doing some research using flight data, but I'm not particularly versed with aviation. From a quick look, it appears that, say, a flight with callsign SAA203 will always be departing from Johannesburg, South Africa and arrive in JFK Int'l airport.

Is this sort of thing always the case, are callsigns only changed when a flightpath is retired, or can a given callsign correspond to multiple flightpaths?


texts: Why does Airbus continue with the A330-800neo despite only having 6 orders?

texts:
Airbus rolled out the first Airbus A330-800neo out of the paint shop last week (see press release).

Until now, this type has only six orders by one airline (U.S. Hawaiian Airlines, who switched orders from the A350-800 to the A330-800neo), with no new orders in the past months. According to various sources, even those six orders by Hawaiian seem to be questionable (see Hawaiian seeking A330-800neo alternatives).

Update 02/22/2018: The only customer, Hawaiian, has canceled their six orders.

Given these circumstances, why does Airbus continue to develop, produce and flight test the smallest A330neo variant? What is the business case for Airbus with one single customer?


texts: why does the concorde's nose go up and down

texts: I have wondered this when looking at pictures of the concorde and sometimes it was down and other times it was up and why cant the commercial airplanes have this system.


texts: Where can I find Boeing 777 safety records?

texts:
I have booked flights for our family to travel Australia - Europe return with EK.  My nine year old son is an aviation geek and since learning some details of the EK B777 crash in DXB (and also the OZ 214 crash)   he has become very concerned about flying B777.  I took that into account when booking flights and booked A380s all the way through (booked with QF due to airpoints but EK flights) but since booking the DXB - PER flight is now showing as a B777-300ER.  He is in tears and refusing to fly on it.  He is prone to some anxiety and is adamant that he won't be getting on the B777.

Is there anyone that can alleviate his fears?  I have read and read articles out to him (which is how I ended up here) but he won't hear any of it.

My only hope is if someone with actual knowledge can provide some safety information that will convince him that it the B777 is a safe aircraft.

Many thanks in advance.


texts: Why are airliners not inherently "speed stable"?

texts:
In a light aircraft, once the pilot has trimmed for a speed, the power controls the pitch (climb/descent rate).

I don't know the technical name for this stability, so I chose "speed stable" for now.

The fly-by-wire (FBW) of the 787 (for example) mimics this behavior:

  In flight, the pitch trim switches do not position the stabilizer directly, but make inputs to the [Primary Flight Computers] to change the trim reference speed. The trim reference speed is the speed at which the airplane would eventually stabilize if there were no control column inputs. Once the control column forces are trimmed to zero, the airplane maintains a constant speed with no column inputs. Thrust changes result in a relatively constant indicated airspeed climb or descent, with no trim inputs needed unless airspeed changes.—787 FCOM

I.e., once a speed is trimmed, the top sentence becomes true like in light planes.

So the related questions are:

What's the name of this stability?
Is it limited only to light aircraft?
Is it related to having a trim tab instead of a stabilizer trim? (Just a speculation.)
How can an airliner without FBW be designed to be "speed stable"?

An answer doesn't need to address the exact questions in order, I'm just communicating what I'd like to understand.

2019: The impact of the third point still confuses me:

Once the speed is trimmed (and left alone), and power is increased (for example), wouldn't having a trim tab (like on a typical light plane) have more impact on pitch response (speed stability) compared to the now-fixed stabilizer (jet-liner)? In other words, a light plane would pitch up quicker (elevator responding to the increase in airspeed), while a non-FBW jet-liner would pitch up much slower (stabilizer unaffected by airspeed) and gain more speed compared to the earlier trimmed state?


texts: Are there any remaining flying boat or seaplane airliners in operation?

texts: Is there anywhere in the world that still offers scheduled air carrier service using flying boat / seaplane types of aircraft - something akin to a proper airliner? Or are they all limited to charters and shuttle-type flights on de Havilland Otters and the like?


texts: What is the equality theory, or equal transit time theory, and is it supported by scientific evidence?

texts:
Throughout flight training when learning about the mechanics of lift I read and was taught this story about two molecules that part ways at the wing tip and reach the trailing edge of a wing at the exact same time. Later on I heard this referred to as the "equality theory."

The idea is that a wing makes a molecule travel farther to end up at the trailing edge at the same time rendering a greater velocity and a lower pressure through Bernoulli's principle.

I'd like to find the best articulation of the equality theory as well as information on whether scientific research actually supports it. Whether it's scientifically supported or not, it may at least serve as a useful teaching tool. In any case, if I talk about it I'd like to be able to cite something truly scientific.


texts: What is the history of Concorde motto "May Concorde bring people closer" and medal?

texts:
I found this image of a medal figuring Concorde and a globe with two contours of continents, before and after Concorde, expressing the new speed of air transport with a motto "May Concorde bring people closer." ("Que Concorde rapproche les hommes").

As I find this material extremely relevant to express the global geography of time-space during the supersonic period, to I would like to know more about it:

Where does this medal and motto come from?
Was it present onboard?
Was it used in other forms of communication?


texts: Does the A320 Trimmable Horizontal Stabilizer automatically reset after landing?

texts:
Does the A320's Trimmable Horizontal Stabilizer (THS) automatically reset after landing? If so, is there any condition where it doesn't? And what about the rudder trim?

I'm asking because I'm studying from an old FCOM I found online and it doesn't state that any of those automatically reset but there are two questions in SmartCockpit that say otherwise (i.e. that both the THS and rudder trim reset after landing).


texts: Did the "feeler" ailerons of the B-52A-F make air-to-air refueling easier than with the B-52G/H?

texts:
The B-52G/H uses 8 spoilerons (so it has 8 burning and 8 turning on its wing) and a shortened vertical stabilizer.  Spoilerons seem to be very effective for this design, further reducing the need for a conventional rudder and ailerons to yaw and roll the aircraft.

The B-52A through B-52F had what have been described as "feeler ailerons".  But their elimination meant that the aircraft no longer has pure roll control, making maneuvering up to a tanker a bit more cumbersome, as inputs from the spoilerons would swing the nose from side to side.

It did occur to me that the tanker, and its boom, would do most of the adjusting, but was the "D" easier to handle in these situations? A response from someone with actual experience would be greatly appreciated.


texts:
What are the differences between pre-transistor and transistor era jet engines? Towards the end of the second world war, most of the air powers had started development on jet engines. From what I understand, all of this predated any practical application of transistors. The transistor era obviously gave way to integrated circuits and microprocessors. On any piston engine I can usually spot the evolution of components because I'm well versed in the operation of piston engines. For jet engines it is less obvious to me, there are for example differences between turbofan and turbojet engines. I superficially understand the difference between them but I've never even operated one, much less been hands on with it.

What are the significant changes from pre-transistor to transistor-era jet engines? I've never seen vacuum tubes used on jet engines so it doesn't seem like it is just a matter of "they replaced the tubes".


texts: How are flaps sized in order to give necessary delta CLmax?

texts: Given an airfoil and wing planform, what is the process to find the flap size and deflection necessary to give a certain change in CLmax? Flaps are usually sized as a percentage of the chord, with 0.2c to 0.3c being the normal range for most aircraft. But how do you find the length of the flaps spanwise?


texts: What materials are used for aircraft windshields?

texts:
Is hard plastic or some form of plastic replacing glass in aircraft windshields? Any idea/companies/players in this field??

I have heard there is recent trend as plastics are light in weight and have properties comparable to that of glass.


texts:
Can a private pilot get a Reduced Vertical Separation Minimums Letter of Authorization from the FAA?

I am looking at this checklist on the FAA site and it asks for a business address. Can private pilots get this as well?


texts: How can I find telephone numbers for FAA ATC facilities?

texts:
It is often desirable to call an FAA air traffic control (ATC) facility on the telephone:

To ask a question about a "mark-the-tape" incident
To request a tour
To notify the facility of unregulated nearby operations like RC plane flying

How can one find the non-emergency telephone number for an ARTCC, TRACON, or control tower (ATCT)?


texts: Does adding flaps during ground roll perform better in short-field takeoff?

texts:
In most POHs, the flap configuration for short-field is usually recommended as partial flaps, for instance 10˚ for C172.

I remember the arguments are that full flaps would reduce the acceleration rate, and in no flaps the airplane would have to accelerate to higher speed to off the ground. In either case, the ground roll distance is longer than the optimal partial-flap configurations.

However, this assumes a fixed flap setting during ground roll. How about let the airplane accelerate to a certain speed (in zero flaps) before adding to full flaps? We could achieve best acceleration as well as best lift-off speed?


texts:
Currently doing my CPL and in class we were shown a formula on how to calculate the true altitude, which as I understand it is the distance between the ground and the plane while taking into account non-standard temperature. Basically, what a radar altimeter would read back to you.

The formula I was given for this lesson was the following:
$$
\begin{equation*}
\frac{\tiny{(Indicated~Altitude-Airport~Elevation})}{1000}*\small{(STD~Temp.~at~Indicated~Altitude-Actual~Outside~Temp.)*4}
\end{equation*}
$$

I have a hard time wrapping my head around the logic of this equation. For instance, why is it that we would need the airport elevation to figure out how high we are relative to the ground below us?

Also, why is it that we can't simply use the part in the density altitude formula that derives the altitude change incurred because of the difference between OAT and standard temperature at a given altitude?

Let's take the following problem:

  Airport Elevation:   500ft MSL

  OAT:                  -10c

  Mountain Height:    2000ft MSL

  Indicated Altitude: 2500ft

  QNH:                 29.42

  Given the following information, will the airplane clear the
  mountains?

The way I would personally calculate it is by converting indicated altitude into pressure altitude, then calculating the difference in temperature between OAT and standard temp. at pressure altitude, then multiplying that number by 117 (as you do to find density altitude). In that case the equation would be as follows:

$$
\begin{equation}
Pressure~Altitude=(29.92-29.42)*1000+2500\\
Pressure~Altitude=3000ft\\
\Delta T=(15-\frac{2}{1000}3000)--10\\
\Delta T=19\\
True~Altitude=2500ft-\Delta T*117\\
True~Altitude=2500ft-19*117\\
True~Altitude=277ft
\end{equation}
$$

This answer however, turns out to be wrong according to my instructor though he was not able to give me an explanation on why that was beyond saying that I shouldn't think too much about it and just apply the formula that was given. That formula gives a true altitude of 2348ft for the plane, meaning that it will clear the mountains by about 300ft.


texts: Can I listen to control tower frequencies on a ham radio legally

texts: Is there a frequency I can tune into to listen to airport I’m in Durham by RDU AIRPORT and would like to listen in on a ham radio only legally


texts:
https://www.ecfr.gov/cgi-bin/retrieveECFR?gp&n=14y2.0.1.1.2&r=PART#se14.2.61_1183

The or below is very confusing.  Doesn't it mean I need an Instrument rating or one of the things that follows it in the list?  Or means one or the other, not both.
Furthermore, when would one of the things that follows in the list NOT apply?

(2) An instrument rating, or privileges on that person's pilot certificate that are appropriate to the flight instructor rating sought, if applying for—

(i) A flight instructor certificate with an airplane category and single-engine class rating;

(ii) A flight instructor certificate with an airplane category and multiengine class rating;

(iii) A flight instructor certificate with a powered-lift rating; or

(iv) A flight instructor certificate with an instrument rating.


texts: If the Concorde had an engine fail at cruise altitude, would they enter the coffin corner?

texts: I know the coffin corner is only meant for subsonic aircraft, but if the Concorde is just cruising at Mach 1 and had an engine failure and also lost that afterburner, would it enter a coffin corner situation?


texts: Who checks the instruments and avionics before the crew boards an aircraft?

texts:
Before the crew boards the aircraft for a commercial airline flight, is there anyone who checks the instruments and avionics system? I'm sure the engines are checked  but what about the avionics systems, instruments, sensors,etc.?

There was an accident due to an incorrect reading of the pitot sensor, is there somebody to check it?


texts: What do these weather depiction chart symbols mean?

texts:
I have several present weather symbols from the weather depiction chart that I'm not clear on and AC-0045 doesn't have in it's legend.

I know the mist and fog symbols, and these look very similar, but I'm not sure what the broken lines imply.  I've added three variations on the symbol below.


texts: Why do localizer/glideslopes use 90/150Hz specifically?

texts:
Why is it that localizer and glideslope system are using 90 Hz and 150 Hz frequencies only, instead of some other LF such as 75 Hz?

Part two of my question:
How does the modulation depth differ for aircraft using localizer and GS receiver?


texts: Why is the landing gear lever not set to OFF on the ground?

texts:
Several older airliners (e.g. Airbus A300, Boeing 737 until the NG series, Boeing 747 until the -400 series) have landing gear levers with three positions: UP, OFF and DOWN. OFF (or NEUTRAL for Airbus) means the hydraulic pressure is removed from the system because the gear is held in place mechanically. See also Why does the landing gear control have 3 positions (up/down/off) on Boeing 737-800?
The gear lever is typically set to the OFF position after the gear is retracted during the takeoff and the system therefore remains unpressurized during the flight:

Pilot Monitoring After flap retraction is complete:
[...]

Set the landing gear lever to OFF after landing gear retraction is complete.

(Boeing 737 NG FCOMv1 NP.21.46 - Normal Procedures - Amplified Procedures)
The gear is then lowered by selecting DOWN before landing, but it is not selected back to OFF after the landing gear is extended. I can understand why this would not be done during the landing phase (redundancy by keeping the gear pressurized down, reduced crew workload during highly critical phase of flight), but why is the lever not selected back to to OFF after landing?
Every procedure I can find lists the gear lever as DOWN on the ground:

Landing Gear Lever:

Check the L/G lever DOWN and the EMRG retract pb protected.

(Airbus A300 FCOM - Cockpit Safety Inspection)

LANDING GEAR lever .....................................................................DN
Verify that the green landing gear indicator lights are illuminated.
Verify that the red landing gear indicator lights are extinguished.

(Boeing 737 NG FCOMv1 SP.6.1 - Supplementary Procedures - Electrical Power Up)
Hydraulic pressure is not required to keep the gear down:

Landing Gear Extension
When the LANDING GEAR lever is moved to DN, hydraulic system A pressure
is used to release the uplocks. The landing gear extends by hydraulic pressure,
gravity and air loads. Overcenter mechanical and hydraulic locks hold the gear at
full extension. The nose wheel doors remain open when the gear is down.

(Boeing 737 NG FCOMv2 14.20.2 - Landing Gear - System Description, emphasis mine)
And furthermore, hydraulic pressure is lost anyway once the engines (and electrically powered hydraulic pumps) are switched off on the ground. So why would you want to keep the gear pressurized down on the ground until shutdown and again during startup?


texts: Is possible to do a private pilot license training and check-ride on a Light Sport Aircraft?

texts: I am planning to do my Private Pilot License. Is it acceptable to do all my training and Check-ride on a LSA?


texts: How "over-engineered" were old planes and how "over-engineered" are they now that we have more advanced testing and research options?

texts:
I've seen several times on shows on television, and even talking to older pilots, where they will tell me that old planes were "over-engineered" to add some margin for errors on the designed engineering calculations. Of course, no specifics are given, and so I was thinking in this current age of super-fast computers, better wind tunnels, new software tools, and decades of actual experience, when people design new planes, how much of a margin to they design into them now?

It seems like confidence in computer modeling seems to be pretty high, and "over-engineering" seems to have typically meant making things stronger than they "need" to be, more reinforced elements, all things which add to cost and weight of an airplane which are factors that are at odds of profitability and performance.


texts: How can I ensure that I have a mode C transponder?

texts:
How can I make sure my aircraft is equipped with a mode C transponder?

======================

If a transponder has an ALT button does that mean that the aircraft is equipped with MODE C?


texts: Why is angle of attack information not displayed in the cockpit?

texts:
Would not it be useful to have the angle of attack information displayed on the flight display? I know that we have shakers that alert pilot when the critical AOA is exceeded, but still we have cases of pilots stalling the aircraft (sometimes stalling one wing more than other).
I am sure designers have considered this but not chose to display AOA. I am curious what the reason could be.


texts: How widely accepted and used is the International Standard Atmosphere?

texts:
Is it used in the US as well for an example, where there is the US Standard Atmosphere. With different standard models, how widely is the International Standard Atmosphere applicable? Or is it only used in Europe, and some countries outside of it?

Appreciate your feedback.


texts:
I looking for the air quality monitoring devices for a320. How do they look, where they located?
thank you for the help


texts: How can I easily keep track of my landing count during pattern work?

texts:
PPL Student pilot, ~20 hrs
Hi,
whilst doing some pattern work I frequently find myself unable to keep accurate track of the number of landings. There's an AFIS at my home airport who keeps track (because they charge fees) but there are a few "flatrate" (you pay for 5 landings, but it's flat-rate after 5) air fields or some free gras strips where nobody keeps count.
The flat-rate one is particularly hard, the pattern altitude is just 650 ft and it's very tight, so there's barely any chance even on the downwind to scribble a note on paper or so.
I've tried using a "lap timer" function on my watch, scribbling lines on a tally sheet etc, but am prone to forget to add a line when things get busy. My multi-tasking capability hasn't improved to the point where I can do too many things at once.
An extrapolation of flight time and time per pattern isn't always giving me the correct answer either.
Would the Pros have any tips on what might be a useful way to keep an accurate count of the landings? How are you doing that?
Update 14/07/2020
Based on the @Bianfable's tip, I've installed "Altimeter Plus" on Android, and had that active. I thought I'd share the results with you:

My problem is solved. I've flown 11 patterns, which are clearly visible (marked yellow). I've done two engine failure after takeoff trainings, marked blue. The red marker must have been a sensor error; I don't remember crashing between the first and second landing. The green markers are forced landings w/o power, aborted at about 350 feet each.
The bad thing about it: Although it was gusty and there were strong winds, I can now see that my altitude control could be improved in the pattern. I don't ever remember being more than 50 feet off, but the data suggests otherwise.
Once again, fabulous tips all, but this was the winner. Phone in my pocket keeps count, and provides reprimands to beat oneself up about after landing. Great! Even provides pretty accurate flight time, next time I'll try and activate it on top of the hour for easier calculation of what time second "x" actually is.
Next time I'll also have phyphox running and will measure the acceleration on landing. The next thing to improve...


texts: Why do I hear the "real" engine noise only when the plane is on the runway?

texts:
I understand that (from other answers) planes taxi using engines only. But, when I'm a passenger, then why do I hear the "real" engine noise only when the plane is on the runway?

So, if planes taxi till runway using engines only, then why don't I hear that much noise until the aircraft reaches the runway?


texts: What is the maximum nose wheel deflection angle?

texts: What is the maximum nose-wheel angle of deflection on modern commercial aircraft such as the Boeing 787? Can it deflect to 90 degrees or even more?


texts: Is optimal landing flare related to ground effect?

texts:
Based on other questions it appears that a "flare" is always part of a healthy airplane landing.

This question asked when a flare should be started, and I found it interesting that the accepted answer expressed it in terms of altitude.  Which got me wondering: Is the need for a flare a consequence of ground effect?  And the optimal flare height for a particular airplane a function of when it enters ground effect?


texts: Under EASA regulations, what constitutes loggable flight time?

texts:
It wasn't too hard to find questions and answers here discussing flight time as defined by the US FAA.

However, I'm curious about EASA regulations, and if applicable specifically as implemented in Sweden.

Based on the relevant EASA regulations, at what point do I note the start and end time of a flight for the purposes of flight time logging?

I looked through the copy of the regulations that I have, but couldn't find anything relating to logging (of flight time or otherwise).

Citations, please!


texts: Why are wings always painted grey, regardless of the color of the fuselage? Is there a regulation for that issue?


texts: Is there a good source for estimating the per unit cost breakdown for a classic GA plane like the Cessna 172?

texts:
For instance, on a Cessna 172 what percent is spent on:

Raw materials
Labor actually manufacturing the plane
Testing the completed individual planes
R&D Making the plane (at this point, very little for the 172 I suspect
Certification testing
Insurance
Avionics
Anything I forgot...


texts: Can a private jet take off without notifying anybody and land on private land in another country?

texts: If you have a friend in the USA who owns a lot of land that is suitable for landing a plane, and you own a private jet with 2 pilots in Norway, can you take off in private property without notifying anybody on what you have on the plane and where you are going or anything like that and fly to the USA and land on the property of your friend? Is that legal to do?


texts: Are there any performance details available for the D8 Double Bubble engines?

texts:
For the D8 Double Bubble, what are the thrust requirements for the engines? Has it been stated what the estimated max thrust will be for each engine?

Source: sputniknews.com


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

texts:
I'm writing a sci-fi story involving aircraft and space craft. I'm struggling to get the terminology right for referring to a pilot being 'in the air' either on a mission or a training exercise. I have a feeling there is a phrase for this but I'm struggling to think of it.

The context would be military, as in the following sentence:

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


texts: What is an accurate expression to calculate IAS as a function of TAS?

texts: Does anyone know a good source for an expression of IAS as a funtion of TAS? I was hoping to find an accurate IAS equation that is only dependent upon TAS, static pressure and static temperature.


texts: Can a non-citizen get a pilot job in Canada if they have an FAA CPL?

texts:
I am an Indian national and considering taking CPL classes in the US. Upon graduation I should have around 250 hours under my belt and FAA licenses. Based on my citizenship status and FAA licenses, would any Canadian airline/general aviation employ me? (This is also assuming that I appear for the Canadian license conversion exam, clear it and have my licenses in order.)

Alternately, if anyone knows any other ways to build hours while in the US (like working as a flight instructor on an F-1 visa) please let me know. I need to build a good amount of hours before I can apply to any major air carrier.

Thanks.


texts: Why does the US President fly in an obsolete 747-200?

texts:
The Boeing VC-25A ("Air Force One") is a heavily modified 747-200. The two current airframes (SAM 28000 and 29000) were put into duty in 1990 and are slated to be replaced in 2017, although I suspect that latter date is optimistic.

These two 747-200s are among the last remaining 747-200s in service. I suspect that they are the best-maintained 747-200s in the world and they have considerable sunk costs in their custom rigging, but even when the aircraft were put in service in 1990 their model had already been replaced by the 747-300 (1982) and 747-400 (1989).

Why hasn't the VC-25A been replaced to keep up with the times? A 747-400 airframe is lighter, faster, and bigger (let alone a 747-8). These would all seem to be suitable features for what is most probably the most important aircraft in the USAF fleet. Is there some attribute of the 747-200 that makes it particularly well-suited for this role despite its obsolescence in the market?


texts: What could be the cause of an uncommanded roll at high speed?

texts:
I have a problem with a T-38. There is uncommanded roll to the left when the aircraft flies at 250 knots. But as the aircraft speed goes up around 500 knots, the uncommanded roll is now to the right. During 500 knots we could control the plane with 15-20 aileron trims.

What may be the problem?

We have replaced a lot of systems and cylinders. And we changed the travel limits of aileron, flap, rudder, and horizontal stabilizer. But no change has been observed.


texts: What's is the difference among ECL, CFL, RFL, TFL messages in ATM?

texts:
These are several messages to provide a change level during air navigation. Some are sent or requested by the pilot, others by the air traffic controllers, etc. There are subtle differences. Could anybody provide an explanation to show their differences?

Related question: What is the difference between RFL and ECL in Air Traffic Control?


texts:
Reading this question and the great answer to it talking about Snowbird sustained human powered flight visible here,

I was wondering and still cannot find nor figure out how power is converted from rowingbike to this smooth graceful flapping motion. What does this transmission look like?


texts: More information on PanAm's first trans-Pacific flight

texts:
I have came across this answer, about PanAm's first trans-Pacific flight (SFO-MNL route via HNL, MDY, AWK and GUM). For the text, I'm working on, I was wondering, if there is any source that can provide more information on this route.

Literally:

years of operation,
approx. times needed to flight each segment,
approx. break times (refueling?) times at each mid-point,
was passengers allowed to leave the airplane during each break?

I'm also interested in getting answer to a question that might be harder to answer (too broad?). How it was possible to service / refuel airplane on airports marked as uninhabited in the original answer (MDY and AWK)?


texts: How are jet engine RPM cycles used to monitor LCF life?

texts: Can someone please define what are N1 and N2 throttle cycles? These are used to keep track of the accumulated low cycle fatigue (LCF) life of rotating components. But I cannot find an exact definition of them.


texts: What is the validity duration of FAA Medical for international flights?

texts:
FAA Rule:

The duration of FAA medical certificates is specified in 14 CFR 61.23.

An example would be for:

A first-class medical certificate
Applicant is under age 40
Applicant is an airline transport pilot certificate for pilot-in-command privileges

In this case:

  Then your medical certificate expires, for that operation, at the end of the last day of the 12th month after the month of the date of examination shown on the medical certificate.

So this clearly states that if I pass my medical on January 1st 2014 then my medical is good until the end of the day on January 31st 2015.

ICAO Rule:

However, I have been told that ICAO rules state that the medical expires 12 months to the day from when it was issued, which would mean that it would no longer be valid as of January 1st, 2015.  (A reference for this would be great.)

Question:

As the holder of an FAA pilot license, with the above FAA issued medical, may I legally fly outside of the US after January 1st 2015 (but before February 1st 2015)?


texts: What happens to Ryanair aircraft after they leave the airline?

texts: According to the fleet renovation and the short age of all their aircraft (6.5 years), what happens to Ryanair's aircraft after their time in the company? Are there other companies willing to accept Ryanair's aircraft configurations?


texts: How does the G1000 differ from an airliner’s avionics?

texts:
I'm going through my multi-engine rating, and my flight training has always been on the G1000. I've had a simple system course on the CRJ-200.
In terms of IFR flying, I really don't see much difference between the two avionics in terms of procedural functionality, except for the FMS.
Anyone can point out what are some of the major differences between the two?
This question is only out of curiosity.


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

texts:
Could someone kindly explain as to how the lift improvement package on the A320NEO enable it to approach at a slower speed compared to the IAE CEO. I have the list of the modifications which is done but it doesn’t explain how it helps.

They are:

Slats (de icing slay/track shutter modifications and stiffened slat/track seals)
Slat 1 enlarged horn
Adding an outboard nacelle strake
Fuselage wing fairing root fillet aerodynamic improvement
Wind shroud close to flap 1 and 2 junction
Introduce extended trailing edges on spoilers 1 and 2 and on fixed wing box trailing edge between spoilers 1 and 2.

These modifications mainly allow the aircraft to approach up to 5 knots slower than our CEOs. But how exactly do the modifications work in reducing the approach speed?


texts: Where does the term “throttle quadrant” come from?

texts:
The area of many flight decks that contains throttles or thrust levers is often referred to as the “throttle quadrant” or “thrust lever quadrant” even if it’s not one of four parts of the panels.

Where does the term come from?


texts: A380 reverse thrust on only half the engines

texts: I noticed on this video of an A380 landing in rain that reverse thrust was applied to only the inboard engines. Do the outboard engines not have reverse thrusters? If they don't, then why not? If they do, then why not use them on a slippery landing?


texts: Under what legal standing can after-hours ground access to an airplane be forbidden? (USA-specific only)

texts:
This came up when a friend was unable to access his airplane because the security guard refused to open the gate. It was a mountain flight in a small plane, and so a timely departure was urgent for safety. The security guard didn't have a reason not to let the pilot access his plane, he simply felt he didn't have the authority to make that decision.
In the end, he was only delayed 45 minutes and didn't miss his weather window. But after I heard the story, it got me thinking what we should do when confronted with this situation, especially if the delay will cause severe consequences (missing a weather window, for instance).
In the US, under what normal conditions can a pilot be forbidden access to her/his plane, and what are the legal justifications for that? I have flown out of the obnoxious KBED and so am familiar with heavy-handed escorts, but this is different from arriving after-hours and being simply prevented from accessing your airplane. That would seem to run afoul of rules about private property, esp. since the tie-down is freely accessible if you fly in.
Generally, as a pilot I have always understood that I have the right to access any public airport for normal flight activities, baring some kind of NOTAM or other abnormal situation.
Are GA airports typically accessible 24/7? somewhat touches upon this subject, but it isn't well documented that these are "private (or state-owned) businesses". Indeed, airplanes and public airports are regulated by the FAA, and as such probably fall under all kinds of interstate commerce laws.


texts: What exactly does the term "fly-by-wire" mean? Where did it originate? I understand that it refers to control systems. If an aircraft is not fly-by-wire, what is it? That is, what are the alternatives?


texts: What is the differences of ADS-B and geometric height?

texts:
Why does ADS-B and geometric height (calculated height) differ from each other?

If the geometric heights are calculated at night where the temperature is lower, then the result should be different during the day, right?

Is ADS-B with night or day calculated height smaller?

What is the more accurate result to be referenced?


texts: What distinguishes the Airbus-Sidestick from an ordinary gaming joystick?

texts:
I don't think the Sidestick in Airbus aircraft is an ordinary gaming joystick that is plugged via USB into the Airbus Computers. I guess it is something very special, because it's one of the most important and critical parts of the aircraft.

What are the differences between an ordinary gaming joystick and an Airbus Sidestick?


texts: Would FAR 91.227, or any other regulation, forbid use of ADS-B-out in an unregistered ultralight?

texts:
In the US, would FAR 91.227, or any other regulation or law, forbid use of ADS-B-out in an unregistered ultralight?  Could the N-number field simply be left blank, without violating any regulation or law?
What about a transponder with no ADS-B-out?
One possibly relevant detail: FAR 91.1(e) exempts ultralight vehicles from all of Part 91.


texts: What operational aspects of Alphabet's Wing drone delivery service will be the same as that of an airline?

texts:
The NPR News article and podcast FAA Certifies Google's Wing Drone Delivery Company To Operate As An Airline begins with:

The Federal Aviation Administration has certified Alphabet's Wing Aviation to operate as an airline, in a first for U.S. drone delivery companies. Wing, which began as a Google X project, has been testing its autonomous drones in southwest Virginia and elsewhere.
"Air Carrier Certification means that we can begin a commercial service delivering goods from local businesses to homes in the United States," Wing said in a statement posted to the Medium website.

The article, plus the BBC News's Google Wing drones approved for US home deliveries indicate that Wing (owned by Alphabet, which also owns Google) will be he first US drone delivery company to be run as an airline.:
See also Medium.com's Wing becomes first certified Air Carrier for drones in the US
Question: What operational aspects of Wing will be the same as that of other airlines? They won't sell seats of course, but will the file flight plans for example? Will they have licensed human pilots to oversee the drone's flight?

The Wing company, a Google spinoff, has won federal approval to operate its drone delivery system as an airline in the U.S.  Credit: Wing, Source

Customers who took part in Wing's drone delivery test program in Virginia approach their package after it was dropped on their lawn. Credit: Wing Source


texts: Why do some pilots call a go-around an 'overshoot'?

texts:
A couple of months ago I was watching some Ice Pilots NWT re-runs, and I noticed they kept saying 'overshoot' when talking about a go-around. Is this standard Canadian phraseology? Or is it perhaps old phraseology? Or is it simply reworded for the benefit of the TV audience?

I'm not asking about the meaning of the word 'overshoot' which is quite clear, but it was being used were every pilot I know would use the word 'go-around', i.e. calling "overshoot, overshoot, overshoot" when shoving the throttles forward.


texts: Is there a particular reason that EasyJet uses U2 as their code?

texts: Does anyone know why EasyJet uses U2 as the prefix for flight numbers? Other airlines have more logical prefixes. Eg. KL -> KLM, AZ -> Alitalia, BA-> British Airways, etc. Even though they do not always match the airline name exactly, they do mimic the name.


texts: What is the difference between MIL-H-5606 and MIL-PRF-5606 hydraulic fluid?

texts: what is the meaning of PRF here and can you differentiate them visually ?


texts: How does switching off pumps and putting on MAN switch resolve low pressure?

texts:
FUEL
  If the center tank is less than 200 kg (440 lb) for the flight: Apply the following procedure, if your airline is affected by FUEL CTR TK PUMPS LO PR cautions on ground or in flight when the center tank is less than 200 kg (440 lb):

  FUEL MODE SEL pb sw ....... MAN

  CTR TK PUMP 1 pb-sw and CTR TK PUMP 2 pb-.....OFF

I came across this while reading Normal Procedures. Could someone kindly explain as to how the centre tanks pump low pressure gets resolved by following the above mentioned procedure?


texts: What’s that weird sound during spool up on some aircraft?

texts:
Some engines seem to make this characteristic “wailing” noise when spooling up. A good example of such is from 0:50 to 0:54 in the following video:

               . I’ve also heard it on a300s, 767s, and md-11s. Does anyone know the source of this noise and why it only occurs with certain engines?


texts:
In trying to understand pressure altitude better, am I wrong or right when I say this?
I am at an airfield. The pressure altitude at that airfield is 200 ft a.m.s.l.
If I set subscale 1013 mb on my altimeter, the altimeter should, theoretically, indicate 200 ft a.m.s.l.
Am I wrong or right when I say this? And am I right in thinking along these lines in trying to understand pressure altitude better?


texts:
I remember building a radio controlled model in the early 90s with concave wing  ribs/surfaces top and bottom...both sides of the wing were undercambered...

It was a very great flying model...60" wingspan...and it flew as well as any other airfoil design...it was a testy build, covering the wing surfaces with monokote..other than that it was a fun craft...never understood how it flew so well by violating all the 'rules?'


texts: What's the theoretical background of the critical angle of attack?

texts:
The critical angle of attack seems to be at all (most?) airfoils around 15-20°. Why is that? Why is it in this range and not lower or higher? Is it just the result of optimizing airfoils? Or is it some inherent property of the air an airfoil is moving through that determines it? (Let's limit the question to subsonic flight.)

PS: I read the answer to "Does airspeed affect the critical angle of attack on an airfoil?" and don't think that this is a duplicate since the other one was more generally about "what are the factors that determine the critical AoA" while I'm asking why the critical AoA seems to be always in this range for most airfoils on planes flying nowadays.


texts: What is the capacity of the vent surge tank in an A320?

texts: If the wing tanks of an A320 are fully filled and the fuel expands due to high temperatures then the fuel overflows into the vent tank. My question is, does the fuel get stored in the vent tank? If yes, how much? If not, does all of the fuel just spill on the ramp?


texts:
A recuperator is a device which extracts heat from the exhaust of a turbine and transfers it to the front air. This heats the air, which means the turbine uses less fuel to heat the combustion chamber to its max operating temperature.
They are used in gas turbines for power generation, because they can supposedly double the fuel economy.
Is this viable in a turboprop? Basically you need 2 heat exchangers per recuperator, so I could understand if they're too heavy. The other thing is potentially blocking airflow too much at the intake, causing too much drag.
Are these problems surmountable in aircraft engines? Is there a way to make them light enough and streamligned enough for aircraft?

The related question doesn't really answer this for turboprops. For jet engines, that related question does explain why it's no good---extracting heat from the exhaust means less jet speed. For turboprops however, it's all about shaft power, just like a electrical generator (before applying power to a prop instead of pure generator).