texts: What is a general rule for crosswind correction, especially when landing?

texts:
I am wondering what is the rule of thumb with correction of the bat?

Is it 2° for every 5kts?

Now i know you can use a E6B.
But im talking about landing ILS or visuals without bracketing the approach.

So lets say you landing on runway 06 the magnetic heading is 060, the wind is 080/05kts.
So would the correction be 062?

The aircraft is a C172

Apologies if this is not a valid question, getting back into aviation


texts: Are paper charts required for flights outside the USA?

texts: Can international flights by a US operator be performed paperless or do you need complete paper charts?


texts: How should I refer to a transition through class B or class C airspace?

texts:
In Seattle, it is common to request a transition over KSEA by asking for either the "Bremerton Transition" or "Kent Transition" (depending on what direction you're travelling). I learned these names from my CFI & have used them with no problem, but I've noticed that on the Seattle TAC they are referenced as Seahawk/Mariner Transition, which refer to which runway numbers to overfly rather than direction (personally, I've never heard these referred to on the radio).

Obviously, "Bremerton" transition refers to transitioning to Bremerton, but I'm curious if this is some agreed-upon lingo or just convention. Could I just as easily ask for a "Port Orchard" transition?

If I were in an unfamiliar area, could I request a transition by referring to any location on the opposite side of the airspace? For example, if I wanted to transition PDX airspace could I request a "Hillsboro Transition"?

Sidenote: I personally love transitioning KSEA. If you haven't done it & are in the area, pick a busy day and request a transition. It's pretty impressive to see the large commercial flights landing right below you. On a non-busy evening, I've heard rumor you can even request a stop\go on 16R


texts: What button is this pilot pressing with his thumb?

texts: In this video (marker 4:23), what button is the pilot thumbing on the yoke?


texts: Is there a formula to calculate how big a ventral fin should be?

texts:
I've been doing some research into vertical stabilizer designs for a university assignment and have come across ventral fins. I've found a fair bit of information on why they're fitted but can't find any formula or rules of thumb to determine how big a ventral fin should be.

I was wondering if anyone knows any of the maths behind ventral fin sizing and the stability it provides?


texts:
Has a civil aviation accident ever involved more than two manned aircraft? Meaning, in one accident: more than two manned aircraft had fatalities or serious injuries or significant damage; or one or two manned aircraft had fatalities or serious injuries or significant damage, while other manned aircraft contributed to the accident, totaling three or more aircraft.
If military aircraft were involved, that would also be of interest, as long as at least one aircraft was civil aviation.


texts:
When new engines are designed for aircraft (military or civilian) they undergo high altitude testing (especially the military ones).

What is high altitude testing of engines? How is that important?


texts: Can a mid wing airplane have no wing spar running through the fuselage?

texts:
Can a mid wing be attached to a fuselage such that no features of the wing run through the fuselage? (so that the pilot can seat comfortably and close to the center of gravity) Airplanes such as the mini max has its wings bolted to the sides. Does that mean there is no main spar running through the fuselage and connecting both wings?

If it is possible, can it be done on the cri cri by Michael Colomban? And what would be the necessary adjustments to the fuselage?


texts: How many tanks are there on an A350? Where are they located? Is it a common configuration among large aircraft?


texts: How is the chord length defined if the wing (whale flipper) is tapering like a wing and has a twist throughout the span?

texts:
Let me be more specific:

I have a 3D scan of a whale tubercle.
The tubercle is tapering and twisting along its half span.
I want to find the mean chord length.

Now let us say that my airfoil section is at 10 degrees. So how is the chord length defined?

a) is it a line that directly joins the LE and the TE (chord length has a slant)
b) is it the line joining the projection of the LE and TE on a flat plane ( slope of chord line =0)


texts: Statistically, how safe are extreme aerobatics flights like this one?


texts: Can anyone Identify this FLY FAIR seaplane?

texts: This photograph, from my family's collection, of a high-winged, dual rotary engine, amphibious airplane, probably in the 1930's, appears to be an excursion plane at a fair since it has "FLY FAIR" written on the wing.  It appears to have the ID number of NC-155, or NC-156, or NC-158. It is difficult to recognize the last number.  I have searched and searched and not only cannot find other photos of this particular plane, but I can't find any photos of an identical plane.  I'm looking for Make, Model, and any additional information you may have. Your help is greatly appreciated.


texts: What aircraft model is this that crashed?

texts: Could someone please tell me what aircraft type this is? The crash happened very near to my flight school a few days ago and I want to know if it was one of their fleet that crashed.


texts: Why are Western helicopters more expensive, yet smaller in size, but Russian helicopters are way less expensive, and larger in size?

texts: So, I was looking around for prices of the Bell 412, Blackhawk and Mil Mi 8/17 prices, and the Bell 412, despite being a lot smaller than the Mi8, was US$2mil more than the Mi8.


texts: What happens to flight operations if no ARFF vehicle is available at a CAT 3 airfield?

texts:
There is a domestic VFR airfield that has the DHC6 Twin Otter as its critical aircraft operating there, making the field an ICAO CAT 1B aerodrome. With regards to ARFF it is a CAT 3 aerodrome and requires 1 ARFF vehicle.

If that vehicle is not in service (broken or not operational), would that mean that the airfield is now CAT 0 for ARFF? Can that airfield remain open/operational if there are commercial flights being performed to and from it (VFR only)?


texts: Can a zero hour pilot actually launch a Bombardier Q400 with only simulator experience?

texts: The thief of the Bombardier Q400 at SEATAC stated that he had a lot of simulator flying (I'm guessing like Flight Simulator for the PC?) Some "experts" stated that he must have had more than that to get the Bombardier off of the ground and flying 'stunts' like loops and rolls. Can a zero hour pilot pull off what apparently did happen or did the thief have to have had much more knowledge? I assume that just starting up the plane to taxi would be a complex procedure, is this easily learned in a PC Game?


texts: At what point are the pilots allowed to communicate with the ground crew whilst they are still in the cockpit?

texts:
The question comes from this comment by Federico

  you cannot be directly connected with the ground crew while the aircraft is autonomously moving (and pushbacks are not used for gate alignment)

Is he saying pilots aren't allowed to talk to the ground crew until the plane is no longer under their control?


texts: What are the guidelines to execute a missed approach during circling?

texts:
Alice is approaching KTCY on RNAV (GPS) RWY 12 at KTCY circle NE to RWY 30. When she is turning right base to RWY 30 final, she loses visual contact with runway environment and decides to go missed. Spotted her GPS map, she notices she is right over the RWY 30 touchdown zone. How should she execute the missed approach?

a) Climb to 700 (600 to 700, HDG 300˚), Climb left turn (~left 260˚ over circling NA region), 3000 direct ECA hold.
b) Climb to 700 (600 to 700, HDG 300˚), Climb right turn (~right 100˚) 3000 direct ECA hold.
c) Climb right turn (~right 100˚) 3000 direct ECA. Note Alice is above circling minimums 600 and initial climb to 700 is based on a HDG of 120˚.
d) Continue fly over LNAV MAP, make a right 180˚, then climb 700, climb left turn 3000 direct ECA hold

In more general senses, does circling nullify the initial climb, initial turn portion for a missed approach procedure, so that we may choose to intercept the following course, navigational radial, or direct to the fix from the side we turn with less degrees?


texts: Why are the tips of the flap track fairings painted red?

texts:
The fairings are painted red at the tips, look:

Source: Airliners.net

I have seen that on many new airplanes, not only the A330. So why are they painted red?


texts: Can a plane with air-breathing engines in level flight achieve enough velocity to make a single orbit?

texts:
A rocket uses engines that carry both fuel and oxidizer. Most are composed of multiple stages and lift a payload to orbit. They are able to burn their engines anywhere in or out of Earth's atmosphere since they carry both fuel and oxidizer. This is necessary to achieve orbital elevation and velocity.

Can a plane with air-breathing engines achieve a high enough speed in level flight such that it reaches orbital velocity? The idea being the plane could use the fuel in its tanks and the air in the atmosphere (at whatever altitude makes the most sense) to gain enough kinetic energy that the plane could then "climb" to an orbit. This would be similar to a zoom climb, but resulting in the plane entering a stable orbit. The plane could burn its engines until flameout as it ascended through the atmosphere. At that time it'd be dependent on kinetic energy alone. The engines, fuel tanks, and other equipment for air breathing flight can be jettisoned at this point if need be.

For the purposes of this discussion, orbit is defined as a trajectory having a minimum altitude of 100 kilometers. Once at this altitude, the vehicle would need to be able to make at least trip around the Earth without requiring additional delta-v from any onboard source. If the path taken was highly eccentric or even whatever it's irrelevant to this discussion as long as the minimum altitude is maintained. There is no requirement for re-entry at a specific location or even that re-entry is survivable by the craft.

The craft could use esoteric materials, fuel sources, engines, and even construction so long as those have been used in at least one prior sub-orbital flight.

If the plane needed a Reaction Control System to control its trajectory once it reaches high altitude this would be acceptable. These systems don't have enough thrust to actually send the plane into orbit.


texts: Can a "crash landing" be used for FAR 61.57 currency?

texts:
FAR 61.57 (a) requires that one must make 3 takeoffs and landings within the preceding 90 days in order to carry passengers.

Does a "crash landing" count for the 61.57 currency? By "crash landing" I mean a landing on which an incident/accident occurs under the NTSB definitions.

For example, if I'm in the circuit to gain 61.57 currency, and on my 3rd landing attempt, I crash the aircraft into a tree well short of the runway. Would I then be allowed to go rent another aircraft and carry a passenger?


texts: How reliable is keeping flight maps on an iPad in the cockpit?

texts: Are flight maps no longer kept on a shelf in the cockpit as a back up in case the iPads malfunction? One story that I managed to research highlighted that this was under debate to rely only on a tablet. For such important documentation, am I to understand that this is due to each airline's discretion?


texts: Is there a service to review prior flight plans?

texts: I was wondering if there is anyone that offers on-line searching of prior flight plans.


texts: In a Vmc demo, why is it important to lose 1 knot per second?

texts:
I got asked two questions on my checkride:

Why is it important to lose 1 knot per second (approximately) in a Vmc Demo?
How do we know we're losing 1 knot per second?

My answer to question 1 would be be: because you are flying with one engine simulated inoperative and creating asymmetrical yaw, if you lose airspeed too fast you might blow past the stall indicator and actually stall the aircraft with a large yawing effect throwing you into a spin. Does that make sense?

For question 2, other than counting 5-10 seconds while losing 5-10 knots of airspeed is there any other way?


texts: What are the locations on the Boeing 737 wing where the airfoil changes?

texts: I would like to know where along the span of the 737 (let's say the NG) wing the two midsection airfoils are used. I am planning on running a CFD analysis of the 737 wing, and I need accurate data.


texts: What is the link OR difference between change in momentum & pressure difference?

texts:
I ask in regards to the the thrust formula, which includes change in momentum, as well as difference in pressure between inlet & outlet of the engine to calculate generated thrust; this implies that momentum change & pressure difference are clearly two (2) different phenomenons.

But in reaction turbine blade cascades, we can observe a pressure distribution similar to that of an aircraft wing, producing lift which causes the turbine to spin, & a load component acting on the turbine bearings. Also, the inlet & outlet momentum change is seen to cause the turbine to spin. I would expect that a turbine's rotation can be explained by either of the explanations but not both together, since the pressure distribution over the blade profile is a consequence of the deflection of air by the blade, which also causes the change in momentum of the flow exiting the turbine. So the force acting upon a turbine blade can be calculated either by calculating momentum change, or by calculating pressure difference, but not as a sum of both.

Now, returning to the case of the engine, of course, there isn't a pressure difference vertically to the axis of an engine, so no force in this direction. But the pressure difference in line of the axis is a direct consequence of the acceleration of the flow (momentum change) through the engine:

So why is pressure difference & momentum change summed together to get thrust?


texts: Do all B777 family aircraft have the same engines?

texts: I think there are multiple variants of engines for the different variants in B777 family but I am not sure but is it GE90-115B in one while Trent and PW in others?


texts: In missiles, what actuators are used for the control surfaces?

texts: In a normal airplane, hydraulics or even cable-pulled systems are used to power the control surfaces. In a missile, that seems infeasible. What device is used to move the control surfaces, and where does it get its power?


texts: What flying boat has the highest maximum takeoff/landing sea state?

texts:
I assume that flying boats have limits on the sea states they’re certificated to take off and/or land in (for instance, hitting a ten-meter wave head-on in a five-meter wooden plane is probably somewhat hard on the plane’s structure, not to mention its contents), the aircraft’s precise maximum sea state rating presumably depending primarily on its size and structural strength.

Which flying boat can legally take off and/or land in the roughest seas?  Are there any flying boats certificated to operate in full hurricane conditions?


texts: Validity of Volga-Dnepr An-124 Grounding in US

texts: Around June 10th, a Ukranian court issued an order grounding 5 of Volga-Dnepr's An-124 cargo planes, citing maintenance checks conducted without OEM (i.e., Antonov) authorization. According to FlightAware, one of those planes (tail no. RA-82078) has been sitting on the ramp at Huntsville International since June 26th, after landing in the U.S. for the first time since the court issued the grounding order. Has the FAA grounded that plane in response to the Ukranian court order, or are Volga-Dnepr leaving it there for other reasons? It's definitely not a grounding of all An-124s, since Antonov Airlines continues to operate An-124s in the U.S.


texts: What should be my basis for selecting an airfoil?

texts:
We're in the process of designing a trainer aircraft and I wanted a high wing aircraft. We calculated this from the profile graphs given on the reports.I know these aren't super accurate since I just projected the values from the graphs.
Don't  mind the highlights


texts: How much do the blades on the V22 or AW609 weigh?

texts:
It seems that the blades on the V22 or AW609 would have to be heavier than conventional helicopter rotor blades since they have to be substantially stiffer when in fixed-wing mode. Normal helicopter blades would flap beyond acceptable levels when exposed to such high forward airspeed. It also appears that since tiltrotor disc loading is much higher, conventional thin helicopter blades would sag excessively.

So, how much do the blades actually weigh?


texts: I'm thinking of building a balloon-launched glider, is this idea plausible?

texts:
So, I know nothing about aviation. I'm a student studying maths and computing and I feel like building a high altitude glider controlled by a Raspberry Pi and Arduino as a personal project.

First things first, I'll be launching using a weather balloon or something to reach a given altitude (references to any information on glide ratios as you get to higher altitudes would be much appreciated). Once it's high enough the balloon will be deflated and released, the glider will then be dropped and start its descent.

Assume I've control of the glider in the form of waypoints I can plot on a map to be put into the onboard computer beforehand (or from signals sent from a computer). How complex an autopilot would be required to follow a set of coordinates (pre-calculated so they fit the descent pattern) and then release a parachute for a safe landing?

I was thinking of purchasing a basic glider structure as to have the maneuverability from the professionally built wings and stuff, so construction shouldn't be a problem. The main concern is how plausible a project like this would be considering I'll be building the flight computer myself and I know basically nothing about flight control.

Any other material you have on flight control, flight computers, personal projects like this would also be much appreciated.


texts:
So - I'm totally confused about FANS and its systems. From what I understand:

FANS 1/A (started in 90s) has some early CPDLC for USA routes (this topic) but what about position reporting? Does it have ADS-C (or other ADS system)? And if it does not, what is used for position reporting to the ATC? Also - is satcom used in the FANS 1/A as a message-transporting service or not? And what is the role of FMS in this system?
FANS 2/B has LINK2000+ CPDLC and ADS-C and uses onboard ATSU to transfer its messages to the ATC. ATSU automatically selects the best form of communication (VHF, Sat, HF...) to transfer the messages. What is the role of FMS in this system? It provides info for ADS-C and provides data to CPDLS or am I wrong?

Thank you. There are so many sources and they differ from each other and I really need to be clear in this.


texts: Can an aircraft on loan in the US be based outside the US?

texts: I'm interested if there is any possible way to get an aircraft (Piper Navajo Chieftain) on loan for a US citizen and then base the aircraft outside the USA?


texts: Why don't all cylinders have priming lines?

texts:
Questions about the primer for carburetor engines.
Why does the primer only spray fuel to three (sometimes just one) of four cylinders. (Like Piper Cherokee or Seminole)
And is it true that priming engine during engine start (cranking engine) may cause engine fire?
That would be great if you could answer those questions! Thank you!


texts:
Is Automatic Flight Control System (AFCS) the same as Fly-by-wire?

If not what's the difference?

  India’s Hindustan Aeronautics Limited (HAL) has carried out the first
  flight of a Light Combat Helicopter (LCH) using an indigenously
  developed Automatic Flight Control System (AFCS), the state-owned
  aerospace and defence company announced in a statement on 31 January.

Source:

https://www.janes.com/article/77568/hal-tests-indigenous-flight-control-system-for-light-combat-helicopter


texts: What type of unit are flaps settings in?

texts: When the flaps are deployed there are different increments on the control lever. When they are set to, say flaps 10 or 40 what is the number indicating?


texts: Should you read back the QNH from an ATIS broadcast?

texts:
A typical ATIS broadcast includes the QNH ("altimeter" for the cousins).

My habit is to read this back since I have effectively been given the setting by ATC and it is required for my startup. For example:

  Finden 37 with information Delta, the QNH 1022.

I can't find any reference on whether this is required or not.  Additionally, do any CPLs or ATCOs on here consider this to be good or bad practice?

If someone wants me to tag with a jurisdiction, then it would be UK CAA since that is where I fly but I am interested in all responses.


texts:
Do (GA) pilots necessarily have to plan every flight, or can someone just go up and fly? Please note I don't mean actually 'filing a flight plan', but does every flight need to be carefully plotted out in advance?

I can get in my car and just drive. If I really wanted to, I could point its nose West and drive until I wanted to stop. In the first years of flight, like during the barn-storming era, a pilot with a plane could hop in and fly as long as he had gas, it seems like there is less enjoyment of "flying for flying's sake" and more 400 hours of planning for a 4 hour trip.


texts: What is the purpose of those casing treatments and how were they designed?

texts:
The images show a kind of casing treatment used in Russian aero-engines.
From what I have found out the first engine featuring this kind of casing treatment was the Tumansky R-13. Since then it was used in numerous Russian jet-engines (e.g. Tumansky R-29 or Klimov RD-33).

Casing treatments are usually used to increase the operating range of compressors. And there exists a wide range of different types/geometries of casing treatments:

I was not able to find any documentation or publication on the working principle of the Russian casing treatments and how they were designed. Since they were designed in the 1950s their design was likely done by correlations. The interesting thing is that the design of the 1970s looks very comparable so the advances in 1. computing power and 2. operating experience did not change them.

Does anyone have information on:

The design rules for these casing treatments (stagger angle, skew angle, axial position)?
The working principle or intent (recirculation, blowing, sucking)?


texts: Why don't aircraft use nuclear propulsion?

texts:
Nuclear propulsion research for aircraft was abandoned during the 50's.

Why wasn't it revived ever?


texts:
The C-130 has proven itself eminently capable of landing on a carrier.

When the S-2 Viking was retired, the Navy didn't really have a good replacement for anti-submarine ops - but anti-sub warfare had also fallen in importance.

Suppose there is a resurgence in need.  The Navy has an excellent ASW aircraft in its inventory; the P-3 Orion (modded L-188 Elektra).  It's not made for carrier operations, but then, neither was the C-130.

Suppose we sort out the smaller details, like making sure the P-3 can refuel from carrier-based aircraft like the F-18 (and thus can take off and immediately tank).  This must be a rolling-on-tires operation; cat launch or tailhook recovery is out of the question.

If the captain can guarantee 35 knot headwind, could the Orion do a "rolling on pavement" takeoff and landing off the carrier?  If needed, it can use the whole deck, obviously it would work better operationally if it could use the diagonal strip.


texts: Why would a C-17 Globemaster be painted in Qatar Airways livery?

texts:
Just seen a C17 Globemaster painted in civilian Qatar Airlines livery.

Any idea for the reason? Is this aircraft for civilian or a military use?


texts: What are these elements on the back of a Boeing 737?

texts:
I forgot the model of that plane but I believe it's a 737.

I labeled each element for clarity.

What are they?

Click here for high-res.


texts: What is the typical temperature of an airliner's hull during flight?

texts: Some high-speed military aircraft like the SR-71 had real heating problems, but airliners also travel almost at the speed of sound, use most of their fuel to make up for frictional losses, so I would presume that their hulls heat up. They are also cooled by the airflow, but at what temperature does equilibrium set in during cruise? I remember that airliners don't seem to be very hot when you touch them after landing, but they have had time to cool down in the slow winds during descent.


texts: Does any USAF fighter jet use surfaces near the front for pitch control?

texts: Some European fighters like Eurofighter use frontal surfaces for pitch control. Does any US fighter use this configuration? And what are these surfaces called?


texts: Did C-124 loadmasters receive parachute and water survival training?

texts: When the position of "loadmaster" was created for the Douglas C-124 Globemaster II, did prospective USAF loadmasters attend the parachute training and water survival school at the 3904th Training Squadron at Fort Carson, Colorado? I believe this school later moved to Stead AFB, Nevada, later the Naval Air Station at Pensacola, Florida (until 2015), and now Fairchild AFB, Washington.


texts: How is the control surface configuration of predator/reaper for redundancy system?

texts:
In commercial aircraft like Airbus or Boeing, there are several control surfaces that work in the same function such as for roll control capability, the control surfaces are aileron and spoiler. Also just like (Correct me if i'm wrong) HSTAB trim as backup of elevator. Because of course it is used for redundancy hence there are no single failure lead to catastrophic. But i read that predator and reaper do not have spoiler. So how the configuration of predator/reaper control surface to accommodate "no single failure lead to catastrophic" in term of control surface failure

Thank you


texts: Do fighter jets have forward-looking radar warnings for missiles, and when was this first implemented?

texts:
Let's imagine a swarm of fighter jets intercepting another swarm. Both groups are moving head-on towards each other. Once they get in range, they will probably lock on and fire missiles.

Do fighter jets have radar that will show and warn of a missile coming head on? Or do they only scan their tails?

I'm interested in when, if ever, such capability was implemented. To me it seems like the 50's and 60's and maybe even the 70's, they would only worry about scanning their tails. It would also be good to document this for both NATO and Warsaw Pact jets.


texts: How are the frequency pairings for localizer and glideslope decided?


texts: What is missing from a non-afterburning engine to prohibit the use of afterburning?

texts: What components are missing in a non-afterburning engine that an afterburning engine does, so that it can't use afterburning?


texts: When does the overspeed alarm goes off in a plane?

texts: I want to know when does the overspeed goes off in aircraft. How exactly is overspeed limit decided? Is it fixed for all the situations, or does it keeps changing? In a game that I play, (Infinite Flight) it goes off at 350 knots air speed for a Bombardier CRJ 200 or Cessna Citation X. But, it seems unrealistic as real planes often easily fly over 450 knots air speed.


texts: Why would a copilot's window be shaded/covered?

texts:
I'm sitting in a small regional airport in Vietnam and I've noticed something odd about the aircraft I've seen arriving and departing. All of these aircraft appear to have the copilot-side window covered or shaded. (The windows are covered from the inside with what looks like the reflective covers you put against your car windshield if you park in the sun to keep the inside of your car from heating up so badly.)

All of these aircraft are ATR 72's, and they're all flown by the same airline. The one I just observed depart had the copilot's side window and cockpit window covered at the time they taxiied to the runway. The one I just saw land had just the side window covered when it taxiied off of the runway and over to the "gate." I can't speak to whether the window was still covered when the plane actually took off since I didn't have a clear view from the airport of the actual runway.

(What I'm calling "copilot-side" is the left-hand side if you're standing in front of and looking towards the tail.)

What is the purpose of keeping some of the cockpit windows covered? Is it a regular practice? (Is it safe? It seems like a safety hazard to cut your visibility in half while taxiing around an airport, even if this place is just an airstrip.)


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

texts: The temperature of the gaseous products exiting from the nozzle is higher than the melting point of the nozzle material. So how do the nozzles survive without melting despite exposure to such temperatures? What is the feature which enables them to do so?


texts: What pose is best for to assume before hitting the ground for survival after failed parachute?

texts:
The title says it all. Assuming one is falling down on a hard perpendicular surface after reaching terminal velocity, what pose provides the highest chances of survival?

My guess would be one of the poses on the picture below (sorry for crude sketch, notice the back is curved):

The rationale behind both is that a lot of energy gets dispersed through the limbs, which are the least vital part of the human body, and the general shape is a slight curve so that the victim rolls over as shown by the arrow, dissipating energy consequently up to his head. I'm not sure which of the two is better: the first one provides a little more protection for the head, but the right one can probably help save more vital organs in the torso in the same way legs do.

How liable is that?


texts: Why would different crossing runways at one airport be on different radio frequencies?

texts:
In this answer the following image was included which shows that control of two crossing runways are on different radio frequencies.

Source: AIP Denmark EK AD 2 - EKCH - AREA OF RESPONSIBILITY

It seems to me that having crossing runways on different tower frequencies could lead to a runway incursion or worse, an accident, if there is any loss of controller-to-controller communication within the tower. One of the key tenants for pilots is situational awareness, and being on a different frequency means that the pilot of an aircraft receiving clearance for take-off on 12 won't know about a plane receiving clearance for take off on 22L at the same time and thus, couldn't question the clearance.

Now, I realize that it's unlikely for both 12 and 22L to be in use at the same time, but if the winds are fairly calm and to the North, it could be possible, especially if traffic was high. However, I seem to recall some discussion here about an (near?) accident that happened on crossing runways where the pilots were unable to see each other as they began their their take-off rolls.

My question is: Why would different, crossing runways be assigned to different tower frequencies since this can lead to a lack of situational awareness and potentially cause incidents?


texts: Why is the planned Kingdom Tower Skydeck unsuitable for use as a helipad? Originally the skydeck was supposed to be a helipad, but this idea was subsequently rejected and the feature was repurposed as a "sky deck" when it was discovered that it was not usable as a helipad, recalling another failed aviation docking boondoggle, the airship mooring mast on the Empire State Building.


texts: Why does the IL-76 have a lump at the bottom of its nose?

texts:
Why does the IL-76 have this lump at the bottom of its nose?
Why can't it be gotten rid of?


texts: Is an RT license required for EASA PPL holders?

texts: Is an RT (radiotelephony) license required in the EU for an EASA PPL holder acting as PIC in an EU-based aircraft?


texts: Could the V-22 Osprey be used as a close air support platform?

texts: I saw the US was looking for a new close air support plane. Why do they not use the V-22 Osprey? It is able to travel slowly and could carry more weapons than an A-10, for example.


texts: What is the standard protocol for landing on the ocean?

texts: If a plane had problems whilst flying and had to land in the ocean, what is standard protocol for pilots and cabin crew to follow in order to try and keep everyone safe?


texts: Could a tilt quadcopter use turbofan engines?

texts: I was wondering whether having a quad tiltrotor would allow for the use of turbofan engine rather than turbo prop. I read on another question that the V-22 uses turbo prop as it is easier to balance, but if there were 4 turbofans then it could surely balance and with the engines closer. Could a turbofan tilt rotor be possible for supersonic speeds and VTOL? And would tilt rotor or tilt wing be better in this application? Also wouldn't turbo fan mean there isn't the stream to worry about between sets of motors?


texts: Are sun's UV rays more harmful on an airplane at high altitude?

texts:
Most airplanes fly at >30k feet, way into the stratosphere / mesosphere where sun's UV rays aren't filtered by lower atmosphere layers.

If the windows of the plane are open and the sun is shinning right on a passenger, will the UV rays be more harmful than those on the earth's surface?
Are there any long term effects if a passenger is exposed frequently?


texts: Why are the boundary layer suction holes placed far forward from the engine?

texts:
Edit: I know that the suction holes reduce the boundary layer; I am wondering if there is a reason why they are placed far ahead of the engine’s intake. My thinking is that the long duct past the holes will form its’ own boundary layer, hence reducing the effectiveness of the holes.

Looking at the picture of the Eurofighter inlet, the suction holes for the boundary layer are located far forward from where the engine actually starts.

Source

Another example is the SR-71 intake - the suction holes are located in the middle of the spike which is also located far ahead from the engine:

Source

Why are the suction holes not located closer to the engine?

Surely, the long duct aft of the suction holes will develop its' own boundary layer - which is what the suction holes were reducing in the first place?


texts:
From an AvWeb post regarding Trump's upcoming vacation to Florida:

  Anyone planning to fly in the area should be aware of the potential
  for Notams that might include gateway operations.

What's a "gateway operation"?


texts: How is oil distributed through the engine in a wet sump system?

texts: A wet oil sump is within the engine crankcase. However, how is the oil distributed throughout the engine and all the other magical parts? I know for a dry oil sump, it's with a oil pump which holds the oil from a reservoir, but for wet oil sump, how?


texts: How would a hole in the side of a plane affect its flight?

texts: Let's say an explosion blew a hole in a plane's fuselage without ripping the aircraft apart or damaging the engine and wings. How would the hole affect its flight?


texts: Was any MiG-29 modernized to incorporate digital systems?

texts:
Did any air force using the MiG-29 ever modernize their aircraft so that they can fly on fully digital equipment such as the following?

Digital HUD
Digital fly-by-wire
Digital navigation system
Digital ...

IOW, from this

Cold-war era Mig-29

to this

Mig-35


texts: Are commercial aircraft designed with a shared data network?

texts:
In modern airliners, do systems like the in-flight entertainment system (IFE) share the same physical and/or logical network as the flight management systems (FMS)? Is there any communication between the IFE and the FMS? Also, is there any Airbus training or procedure that might deal with what to do if flight systems were being tampered with?

I'm asking because an information security researcher named Chris Roberts is in a bit of trouble with the FBI after claiming he hacked into the entertainment systems on Airbus and Boeing airliners and used the access to tamper with the airplanes' flight control systems. Apparently he would connect into a Seat Entertainment Box (SEB) and hack the IFE system. I am an information security professional myself and I have no reason to disbelieve this part given my personal experience.

What I am initially skeptical about is that he has claimed to have successfully tampered with flight control systems using the access gained from the compromised IFE. Specifically listed in this document he has allegedly claimed that he issued a climb command to one of the engines through the thrust management computer, causing it to spool up and temporarily cause the aircraft to yaw. This would only be possible if the IFE were able to communicate somehow with the FMS.


texts: Why don't NK-12 powered contra-rotating propellers turn in equal rpm?

texts:
The Kuznetsov NK-12 is a Soviet turboprop engine of the 1950s, designed by the Kuznetsov design bureau. The NK-12 drives two large four-bladed contra-rotating propellers, 5.6 m (18 ft) diameter (NK-12MA), and 6.2 m (20 ft) diameter (NK-12MV). It is the most powerful turboprop engine to enter service.
   (Wikipedia: Kuznetsov NK-12)

Tupolev TU-95 (NATO codename Bear) and Antonov AN-22 (NATO codename Cock) use the NK-12 turboprop engine, and as can easily be seen in many videos available on the internet, their propellers are not geared in a way that would make them turn in equal rpm.

TU-95 propellers turning ratio is such, that for each full turn of the front propeller, the one behind turns a little more than half a turn: TU-95 engine start on Youtube.

The two frames above show the aft propeller's lag after the forward propeller moved a quarter-turn.

For AN-22 the ratio is one full turn for front prop, and about 3/4 for the rear one: AN-22 engine start on Youtube.

Why such ratios? What is the reason the front propeller has significantly higher rpm compared to the one behind it? The air that has gone through the disk of the first propeller has obviously been accelerated, and has gained a swirl momentum. This would have to be taken into consideration somehow.

My own guess would be that this has to do with the aforementioned flow changes, load distribution between propellers, and/or something with vibrations and resonances of the powertrain.

Please do not hesitate to prove me wrong on this one, but for that to fly, I'd require some hard evidence concerning the NK-12 powertrain.


texts: How could a turbocharger experience over-boosting due to cold oil?

texts:
How can cold oil cause a turbocharged engine's automatic waste gate to stick, leading to over-boosting?

Diagrams I've found online for waste gates don't appear to indicate a connection between it and cylinder oil.


texts: Are modern airliner avionics spill-proof?

texts: I thought about this today, and didn't find much other than a flight decades ago that made an emergency landing due to spillage causing the trim wheel to uncontrollably pitch the plane down into a dive. How spill-proof are avionics today? Especially the centre pedestal? I can't imagine it happens often but it has to happen from time-to-time where a pilot will spill their coffee on the centre pedestal right? It seems like it would be an oversight to not have these be spill-proof.


texts:
The early history of aviation is full of crazy designs, so please allow me this one:

A span wise narrow gap in the wing halfway between the leading edge and the trailing edge.

The door to the gap would be aerodynamically balanced, it would open at slow speeds. The gap cross section would be nozzle shaped to accelerate the air from underneath the wing to the top side. Lowering its pressure.

At the wing root and tip there will be no gap.

The idea is similar to slotted flaps and slats, but with the aim of energizing the aft portion of the wing. Thereby combining slats and flaps into one. Would it work?

In other words, it would split the wing into two smaller wings.

I expect the answer to be no, but would love to know why.

Edit: edges below are meant to be curved.

(Original Image)


texts: Is the autorotation in San Andreas movie realistic?

texts:
San Andreas is an awful movie, but given how helicopter-centric its plot is I'm wondering if they even got the autorotation landing correct?  In the middle of the movie the hero is cruising in (I think) a Bell 412 when the engines fail.  He tells his passenger they're going to autorotate, and he proceeds to do the following maneuver three times: Precipitous pitch down, then after picking up a lot of speed, a flare.  (The final "landing" flare is attempted in a crowded parking lot where he tries a last-second evasive maneuver that destroys the helicopter.)

My understanding is that a proper autorotation always simply consists of pitching to a specified glide path and not changing pitch until the landing flare.  Do any conditions or rotary-wing vehicles call for a different autorotation maneuver?


texts: Other than fighters, which airplanes can fly straight up?

texts:
I would think, for example, all modern fighter jets can maintain 90 degree climbs due to having thrust to weight ratio greater than one.
Are there any other air planes which can do that?


texts: Do the Mt. Everest rescue helicopters have modified engines to operate at high altitudes?

texts:
There are so many climbers on Mt. Everest today that there is now a helicopter rescue service there. They operate rescue up to 21,000 + ft. Because this is essentially stationary service it seems that engine modifications like a larger compressor section would be warranted.

In stories on the internet regarding these helicopters, none mention engines.

My employer had two Rolls-Royce RB211s operating at about 7,000 ft as stationary power and the power rating was cut in half for the altitude, so operation at 21,000 ft is impressive.


texts: Can a turbofan maintain torque when spinning fast?

texts:
I assume turbofan fan rpm could be increased only when:

Using most modern jet engines (Airbus A380 and the Boeing B747-800)
Using a magnetic gearbox which can handle more torque dor the same weight
Fan and compressor blades are reinforced
Design muffles and silences the fan sonic boom
Engine is designed to prevent a flame out.

Assuming the problems above are solved, and one was able to redesign the fan and compressor blades to be efficient at 10 times their current rpm, without changing the power rating:

Would the engine have enough torque and power to spin the fan at cruise altitude?
What would be the effect on thrust?


texts: What Does "By ATC" Mean for an SID Route?

texts:
I can understand that altitudes may be "by ATC", but why can a route also be marked with "by ATC"? All SID routes need prior clearance by ATC, right?

For example, in SID RWY 16 for ZGSZ/SZX, MEPOG-7X and LKC-7X are "by ATC", while others are not. I know that LKC-7X is not a regular route flown, but still: what does "by ATC" mean here?

(Source: ZGSZ AD 2.24-7F, AIP China)


texts: How is a Class E airport distinguished from a Class G airport, based on the identifier?

texts:
Some small uncontrolled airports have "K" identifiers such as KPHK (Palm Beach County Glades) "Pahokee". Others such as 42M (Thayer Mem) "Thayer" have a numeric identifier. Both have 122.9 CTAF listed. Pahokee is Class G, Thayer is E.

My question is how is an "E" airport distinguished from a "G" airport on the basis of the identifier?


texts: What is the difference b/w Normal & Restricted Category for a CG/FS Envelope?

texts: These are the FS (Fuselage Station) Limits Envelope (As opposed to a CG limits envelope), supposedly for a Cessna Citation 560 XL. I would like to know the difference between Normal and Restricted category? And when as I pilot, I would use which envelope?


texts: What is the fastest single-engine civil turboprop aircraft with cabin seating?

texts: I was having a discussion with some friends about general aviation aircraft with cabin-class seating. We were discussing cruise speeds and there were some "shop talk opinions" flying around about what the fastest single-engine turboprop in general aviation is. I'm curious to know who holds the title.


texts: Why do planes not fly "backwards" (up from the planes POV) when in a vertical climb?

texts:
As suggested by a user in this question, I'd like to ask this question:

One of the most basic aerobatic maneuvers is a vertical climb. This can be achieved by just pitching up to what appears to be 90°.

Assuming it is really a 90° pitch up maneuver, wouldn't the lift of the wing (though smaller due to less speed) and the missing gravity to counteract the lift make the plane go "up" (again, planes point of view!)?


texts: What is the decision- and workflow during a strategical rerouting?

texts:
Consider a commercial longhaul flight receives a warning about severe weather on its intendend route, a few hours of flight time out. What would be a typical work- and decisionflow between pilots, dispatchers and controllers for the rerouting of this flight?

To have a more specific scenario, lets assume the flight is bound to the US westcoast from Europe and the pilots receive the weather forecast when already in Canadian airspace (not oceanic).


texts: What is the speed record for the Boeing 747 and Airbus A380?

texts: What are the speed records (true air speed) of these Jumbos: The Boeing 747-8 and the Airbus A380 if any?


texts: What are the design considerations for variable-pitch folding-propellers?

texts:
Folding props are increasingly used on self-launch gliders in order to reduce drag. Here is an example of 1m dia. props from LZ Design's FES system:

For self-launch gliders, due to minimally-sized power plants the props are optimized for the safety-critical climb phase, leaving cruise performance as an afterthought.

At full-scale power levels, i.e. 10-30kW, how are design considerations different for folding props vs. standard fixed-root props?

In specific, could an existing folding propeller be retrofit by simply having a root which pivots, or would the already-structurally optimized root of a folding propeller make this unworkable?

[*] Examples at What are the advantages/disadvantages of a forward-folding propeller?


texts: What determines the maximum altitude a plane can reach?

texts:
What factors determine the maximum altitude for a plane?

Is it limited by wing design, engine thrust, and so on?

Is there a formula by which one can calculate the maximum altitude a plane can reach?


texts: What is the largest aircraft that has been flown inverted successfully?

texts:
What is the largest aircraft that has been flown inverted? For the purpose of the question:

Sustained inverted flight is not necessary, therefore barrel rolls and loops count
The aircraft must be undamaged after the maneuver
The maneuver must be intentional (i.e. China Airliners 006 does not count)
Simulator runs do not count. The question is not "can it possibly", but "has anyone tried successfully".

The largest I am aware of is the Boeing 707, but that was more than 50 years ago. Has anyone attempted a similar feat in a larger aircraft?


texts: How do the vortices of a fixed wing and horizontal stabilizer interact?

texts:
What interaction of vortices between the fixed wing and horizontal stabilizer?

How do the vortices affect the flow of the horizontal stabilizer upon leaving the wing?

when will the downwash effort affect the flow, apart from not having clean-flow?

Does the downwash decrease dynamic pressure the reduce the lift?

Does the Airflow be affected after leaving the wing?


texts: What is the minimum and maximum number of jet bridges used on an Airbus A380?

texts: What is the minimum and maximum number of jet bridges used for embarking and disembarking on a typical Airbus A380 trip and why?


texts: drag force relationship with cube of speed?

texts:
So I saw this physics website that said drag grows quadratically with speed. Meaning the drag force at 200 km/h is 4 times what it is at 100 km/h. Ok I'm fine with that. But then it said the work required to accelerate to that speed grows cubically. Meaning I need 8 times the power to accelerate from 100 km/h to 200km/h? this part I dont get.
So if my imaginary engine was producing x kilowatts or kilonewtons, and I pressed a button and its now doing 4x:

Isnt it logical that I should accelerate if I am going only 100 km/h, since drag isnt 4x yet??
Shouldnt I keep accelerating until equilibrium out at 200 km/h?

Update: the power vs force distinction solves it. I was mislead by the use of the word "accelerate" in that page. I thought it was discussion about drag and acceleration. There is no accelerate. The power required to go from A to B in half the time is 2x larger. And drag grows quadratically.


texts: Is the landing gear controlled by the pilot or is it automatic?

texts: I have been watching a few aircraft landing videos in crosswind situations and I noticed that if the airliner missed the runway the landing gear would go back into the aircraft. So I'm wondering if this system is automatic after a takeoff or if it's controlled by the pilot manually?


texts: Icing conditions temperature range: SAT or TAT?

texts:
Considering the general rule of thumb defining potential icing conditions: temperature between +10 and -40 degrees C and presence of visible moisture,
is the temperature range regarding TAT (total air temperature) or SAT (static air temperature)?


texts: Can a pilot initiate an enroute descent to an IAF without ATC 's approval?

texts:
An IFR flight is cleared DIRECT to a published IAF for an approach at the destination airport. The cruising altitude is 10,000’, the IAF crossing altitude is 2,000’ and the T/D begins about 24nm prior to the IAF with standard rate of descent.

Since route has been previously cleared to that IAF waypoint, can the pilot commence his descent upon reaching the T/D, or wait to hear from controller or request descent instructions just prior to the T/D?


texts: What does the PBY Catalina's APU look like?

texts:
I found some specifications of the PBY Catalina that mention an APU, but I did not find any other references to this APU. It seems  logical that such a plane has an APU, and that this APU is not like modern gas turbine that may be fitted on airliners.

What does the APU look like in this aircraft? Where is it located?


texts: Why do delta-wings perform so well on paper airplanes?

texts: Based on this question, it seems that delta-shaped wings do not perform well at low airspeeds. But why do paper airplanes, particularly the most well known one, fly well even though the airspeed they fly in is at most 15 knots on average?


texts: Why limit the bank angle to 10° when passing through FL300 on a B737-800?

texts:
When passing thought FL300, we are instructed to set the bank angle limiter on the MCP to 10°.

I know one of the reasons for this is that we are thrust limited so maneuver capability decreases.

Are there any other reasons?


texts: What are the options for installing ADS-B OUT in a Cessna Citation to meet the regulations?

texts:
So I have a friend that works for a company that owns a Cessna Citation. His company is looking to comply with the ADS-B regulations. He has been given the task of making a business case for actually doing this, but so far the only thing he's turning up is companies that want to sell the Garmin solution (GTX-345).

The specific questions:

Are there other manufacturers of ADS-B equipment that are recommended (by AOPA, FAA, or any other respectable group)?
What companies (again, respectable) would do installations? Maybe towards the Northeast since that's where he is located.
What sort of considerations do you have to look out for in upgrading to ADS-B? I am assuming it's a transponder replacement that you end up doing, but it also has to tie into a bunch of other equipment. What are the gotchas?


texts: What is the purpose of the little eyebrow windows on the Boeing 737?

texts: Anybody know what these windows were used for?


texts: What's the busiest airport that's not WGS-84 compliant?

texts:
Most latitude and longitude coordinates are defined relative to the WGS-84 standard, including GPS coordinates from your receiver.  However, some coordinates are specified using local datums, and these datums are often imprecise enough that even if you did convert them to the same datum as your GPS receiver, your receiver would be over a hundred feet off. (Code 7700 has more information on the issue).

Some examples can be found through Jeppesen and Garmin, like some of the SIDs around WIII and approaches at FLKK.  I don't have firsthand experience with any non-compliant navaids personally though so it's hard to tell how big a problem this really is.

Nowadays most (95%+) of navaids and airports are compliant.  I've heard even all international Russian airports are now compliant.  So what's the busiest airport with non-standard coordinates?


texts: What is an augmentor wing in the context of STOL aircrafts? and is it still used today? This seems to be a term that I can only find in NASA aerodynamics (specifically powered-lift) research papers in the 70s and 80s. Example reference paper: https://apps.dtic.mil/dtic/tr/fulltext/u2/a177750.pdf


texts: For a supersonic inlet, does an increase in Mach number lead to an increase in adverse pressure gradients?

texts: For a supersonic inlet, does an increase in Mach number lead to an increase in adverse pressure gradients because of the shock waves(which leads to boundary layer separations) and decrease in inlet area?


texts: Could bypass air be used to cool a rocket engine like in turbofans?

texts:
Rocket engines typically employ a cooling jacket of sorts, usually dual-purposing the fuel as a liquid coolant before it flows into the injectors.

Here is an example turbojet using a bypass. As you can see, the bypass air is far cooler in temperature than the air combustion chamber:

Source

Why are there no designs that use an air bypass (similar to a turbojet) to cool the engine/nozzle? Obviously once the rocket has escaped the atmosphere, a bypass would be of little use. However usually by that stage in a rocket, thrust has been greatly reduced and therefore generated heat as well.

Wouldn't a bypass cooling system make a rocket engine a tad less complex (especially for the first stage)?


texts: What would happen if a hot air ballooon was punctured in mid-air?

texts:
I am writing a script for a film where a hot air balloon is punctured and it falls to the ground. There are two teenagers in the balloon when it is in the air. What I would like to know is how fast the balloon would fall the ground. Would it glide down or would it drop? This might be a dumb question but it would really help me out in the story. If it helps at all, the balloon is supposed to crash land on top of a canopy tree. Would the balloon go down like an airplane and crash landed, nosediving towards the earth at a fast speed or would the rest of the balloon slows its velocity down?
I need the characters to survive the crash and the tear will be about 4 inches. Would it need to be longer for the balloon to start descending for a crash landing?


texts: Why are wings not tapered all the way to reduce vortex drag?

texts:
Wingtip vortices are created by, well, wingtips. These vortices create drag. One of the approaches to reducing this drag is taper the wing,

source

source
Will eliminating the wingtip, as on the lower left, eliminate these vortices, and thus eliminate induced drag? Why or why not?


texts: What is the angle of Incidence of wing of Airbus A320?

texts: What is the Angle of Incidence/ Mounting Angle of the wing of AIRBUS A320?


texts:
Airbus just presented its new A220 aircraft, formerly the "old" Bombardier CSeries, that is re-branded after a 50.01% acquistion of Bombardier by Airbus.

It's an aircraft very similar in target and characteristics to its own A320neo Family, so my question is simple... why? If they would cover different market segments this could be a logical choice but in this case, is there not the risk of creating internal competition?


texts: What is the worlds shortest runway for FAR 23 commuter type aircraft?

texts:
This article lists the airport at Saba as the worlds shortest runway at 1300 ft. The runway is built on a bit of flat land on the side of the volcano that makes up the island. Nowadays STOL aircraft land here, previously the aircraft had to come in skimming over the wave tops and zoom climb onto the runway.

The Twin Otter can land here. Does Saba really have the shortest runway on earth for FAR 23 commuter type aircraft, or are there any shorter ones?


texts: How are underground fuel pipes monitored for leakage?

texts:
This question is about environmental risk associated with high pressure lines underground at airports.

My understanding is that there is a matrix of high pressure fuel lines underground to each gate, while the source of the fuel are the main tanks. What environmental (and operational) safeguards are in-place to detect leaks to the environment?


texts: Can I get a restricted ATP based on part 61 training?

texts: I graduated from a college with 60 credits that are related to aviation but I got my IR and CPL from out of school which is part 61. Am I still qualified as a candidate who can apply for a 1000hr R-ATP?


texts: Why does the MiG 21 use anti surge shutters?

texts:
Does the MiG-21 use anti surge shutters at high speed? What is the adverse effect on the airflow at such high speeds (despite using a conical spike ahead) which warrants the use of antisurge shutters?

Look just ahead of the wing root, below the two red triangles. The anti surge shutter is covered with a red coloured blanking secured with a yellow cord.


texts: Why do Airbus and Boeing have different approaches to bleed air systems?

texts:
Reading Wikipedia and other questions like this, made me curious as to why Boeing uses bleedless architecture for its B787, while Airbus thinks differently for its A350 XWB (and Rolls-Royce thinks the same).

Both companies switched to composite materials for their new aircraft so they agree about some new technologies, but not all, since they have different approaches to the air systems.

Why did Airbus remain more conservative on this topic (even if its model is about 5-7 years younger than the B787)? What is Airbus's argument to sustain this choice and how does it compensate the disadvantages (cited by Boeing in linked post) of the traditional bleed air systems?

To be more precise, development of new technologies bring both companies to share many new common approaches because advantages are clearly evident, for example: glass cockpit, composite materials, wing extremities (sharklets/raked wingtip/winglets), bigger fans, but they are different ideas about others, such as control yoke, flight envelope, chevron onto engines and, effectively, bleed air.

I found information about "why" Airbus choices to avoid chevrons or prefer a side-stick joystick for example, but not about bleed air systems


texts: If a warning emerges, why not land as soon as possible?

texts:
This question is based on this episode of Air Crash Investigation concerning crash of Lauda Air flight 004.

Reverse Thrust Indicator warning is shown at 21 minutes and 10 seconds into the video. At the time of flight, such a warning was deemed a non-emergency, though wrongly. Yet should the pilots still have continued the flight?

I would think it safer to err on the side of caution, and try to land instantly whenever a warning emerges? The video depicts the pilots' verbalised guesses and thus perplexity over on the warning's causes.

I anticipate two counterarguments:

Some warnings may be too minor to justify an immediate landing, but where is the line drawn? Anyways, this warning seems dire enough?
Pilots may fear reprisals from their greedy employers for effectively cancelling the flight, for possibly a false negative, but a principled virtuous pilot would prioritise safety over monetary interests.


texts:
In this youtube video, there are several examples at 0:34, 1:15, and 1:27. You can see the runway looks wobbly. That last one appears to have at least three wobbles in it.

These are runways on which large commercial jumbo jets are landing, so presumably they're built to world-class standards. Do these standards allow for such wobbling along they're length? If so how is that possible?


texts: Can an outside observer tell if an aircraft is flying through turbulence?

texts: As a passenger, when I look out of the window, I can see the wings shaking. What would another plane (not in turbulence) see if they were observing the same plane (in turbulence)?


texts: Are there any simulators around to simulate ADS-B data (TIS-B & FIS-B)?

texts:
I am trying to find a simulator like the Spirent GPS Simulators. Are there any Simulators out there which can simulate and generate random traffic and weather information for TIS-B & FIS-B testing?

I have an ADS-B 978 UAT receiver hooked up to an antenna which receives signals mostly from 1 tower. I would like to hook up a simulator to the UAT receiver which can simulate the ADS-B data block (customized). I tried searching via Git and many other places couldn't find one.

Has anybody came across any such a thing? Objective - TIS-B to generate random traffic, FIS-B to generate necessary weather.


texts: What turbine temp. would result from burning pure stoichiometrically?

texts:
I've heard that jet engine efficiency is limited by turbine temperatures---that is, the max temp. that the turbine blade alloy can withstand before weakening too much.
So jet engines are run fuel-lean. But they do achieve > 99% combustion of all fuel, so at least that's good. However, if we could burn stoichiometrically, then the engine could be smaller and lighter since it would need less air intake for the core.
So I want to know what is the max temperature that would result if you tried to burn pure stoichiometric?
BTW, to keep it simple, I'm asking about TIT (Turbine Inlet Temperature), which is the temperature of the gas right after combustion, right before it enters the first turbine stage. You can actually do complicated cooling on the blades to keep them less hot than that temperature somehow but I don't wanna get into that aspect.
Note, I'm interested in any typical large jet engine, like the PW6000, running at cruising conditions.
I found an example of actual TIT saying 1600 C: Mitsubishi site link. However, it was a gas turbine not jet engine, so I can't be sure if this is typical for jets too. What I want to know is the theoretical TIT if you could burn pure stoichiometric, to see what the difference is.


texts: Why does ORD have two towers? I flew in there for a connecting flight this last weekend and saw two towers standing, one obviously larger than the other.


texts: How do the cabin noise levels of the A380 and the 777 300 ER compare?

texts: I couldn't find any official comparison for noise level (dB) in Airbus A380 versus the Boeing 777 300 ER. Does anyone have some info about it? Which one is better in terms of acoustic isolation?


texts: Can different airliners of the same type feel different to a pilot?

texts:
(There's a related question Do two of the same model of aircraft feel different to fly? already. But:

It's not about airliners, and most of the answers concern other aircraft.
Not one of the answers discusses feel - subjective experience. They discuss performance, position and orientation of controls, where the air-vents are, the lighting - but not how it feels (or sounds or even smells). I'm concerned with this subjective experience.)

By "different airliners of the same type" I mean examples of exactly the same model in the same configuration with the same engine options.

By "feel" I mean how the aircraft responds and behaves, as experienced subjectively by the pilot.

Given a pair of cars of the same model in the same configuration, after a year or so you might well find that one feels different: the steering in one may be twitchier or looser, the clutch bites differently, the brakes respond sooner, it bounces more excitedly over bumps, the gear lever is stiffer.

There may also be different noises from the suspension, or sound from the engine at idle. Perhaps one car smells different on wet or hot days.

Are similar subjective differences apparent to pilots of different examples of the same airliner?


texts:
I know that high wingers have an inherent dihedral effect.

Are there any examples of high wing aircrafts with a dihedral?
If so, what is the reason behind it?


texts: Knots vs MPH, is there some standard for when to use which unit?

texts:
In looking at all the sources of aviation data, including POH's, instrument dials, instructional materials, FAA publications, METAR's, flying magazine stories, YouTube videos, etc., I see no standard usage of either knots (nautical miles per hour), or mph (statute miles per hour).  It seems many people use them not interchangeably, but mix them up seemingly randomly.

Is there any kind of agreed upon standard about when to use which system of units?  It's easy enough to convert one to the other (well actually a lot easier to convert knots to mph), but it seems this is just a latent trap for mistakes in navigating and, more importantly, in airspeed errors.


texts: How long does it take to die when we would in altitude that push us to hypoxia?

texts: How long does it take to die when at an altitude sufficient to induce hypoxia ?


texts:
I watched an episode of Air Crash Investigation or something else a while ago,  I want to know which one this was:

What I know is that during takeoff, the aircraft received a warning saying some part of the autopilot wasn't functional however they continued the takeoff as it wasn’t a big deal. They reset the flight computer, but since the aircraft was old and the flap settings and everything was set to normal, the aircraft began banking to the right and it crashed.


texts: Do quadcopter propellers break the sound barrier?

texts: I recently bought a quadcopter and noticed every time I fly it there is this weird buzzing noise. I have heard this noise on other quadcopters around the same size as mine(4in by 4in). On an airliner turbofan engine you can sometimes hear this weird buzzing sound from the engines, which this sound is the n1 fan spinning faster than the speed of sound and resulting in this loud buzzing sound. So is my little quadcopter motors going supersonic or is it something else?Source:(dynomodels.co.uk)


texts: What is the point of making one control surface play the part of multiple control surfaces?

texts: For example, flaperons (flaps + ailerons) and elevons (elevator + ailerons), are all individual control surfaces but play the roles of two different control surfaces. What is the point of making a single control surface, undertake the functions of two?


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

texts: How to calculate the lift coefficient of an airfoil section with flaps and slats if we know the Cl for the individual elements, like Cl of wing, Cl of slat and Cl of flap?


texts: Can X-Plane be used as a professional simulator?

texts: Can X-Plane be used as an actual Flight and Navigation Procedures Trainer (FNPT) level 1 flight simulator with Out The Window (OTW) visuals, separate Instructor Operation Station (IOS) and replica hardware?


texts: Do jet fighters have air conditioning systems?

texts:
In most jet fighters, the cockpit is a glass dome and the pilots are exposed directly to the sun.

In addition, they are wearing flight suits and full face helmets (most of the time).

I can only imagine that with no respite from the sun, the cockpit must heat up very quickly.

What measures are there for climate control or pilot comfort?


texts: What is required by and for flights that cross borders in terms of border control?

texts:
This can apply to countries that have water in between, like the UK-France or US-Canada.

If an aircraft crosses into neighbouring country, does it need to go to a border-controlled airport (with flight plan and access granted)?

An IFR-filed flight with permission from that country's civil authorities, but to a non-international airport.

Are international airports the only border-controlled airports or do some countries have predetermined airports that pilots can fly to, so that border control authorities can process them at said airport?


texts: How far from the runway should a small plane start its descent from 5000ft?

texts:
I don't fly, don't have a clue. But one of the main characters in my book DOES: it's a Cessna 152, just him at 14 stone and a couple of small bags, all conditions are perfect and he's flown from about 140 NM away. Would 5000ft be about the right altitude?

The question is: how far away is the runway (a grass one on an unlicensed airfield) when he starts his descent? It's a direct approach, no pattern.


texts:
Here's a METAR:

  SCEL 090000Z 15005KT 5000 HZ NSC 10/08 Q1020 NOSIG

What does NSC mean?


texts: Is it ever allowed to list your destination airport as the IFR alternate too?

texts: Is it legal (in certain conditions) to have your primary airport of intended landing, also listed as the alternate?


texts: Do modern jet engines monitor and record exposure to particles of dust or sand?

texts:
The BBC News article The Jet Engines with Digital Twins describes engineers monitoring measured versus modeled behavior of jet engines, and deviations between them signaling possible need of maintenance.

The following mention of sand:

  One of the most useful parts of the digital twin is that it measures a huge number of factors that the engine faces throughout its lifetime -- some flights have more people on them then others (that will put more strain on the engine), some cities (like Abu Dhabi) have a lot of sand in their air, and some pilots push their engines harder than others. “With the twin...I can learn that the pilot is a cowboy and pushes the engine. The fuel burn we see will be different with different pilot. The digital twin remembers every one of those events. (emphasis added)

made me wonder if modern jet engines monitor and record exposure to particles of dust or sand. If so, roughly how do the airborne particle monitors work - do they monitor the size distribution, or just count number over a certain threshold of some kind?


texts: Was there more than one incident or accident where an Airbus FBW aircraft reverted to mechanical backup?

texts:
There was an accident Smartlynx A320 training flights MYX-9001 at Tallinn on Feb 28th 2018, where ELAC pitch control failed due to fault in the stabilizer actuator, and then both SECs failed due to the command and monitor boards responding differently to a short bounce, so only mechanical backup was left for pitch control (fortunately the crew managed to land the aircraft and had just some broken panels).
It is the only instance I heard of where the mechanical backup had to be used. Was there any other incident or accident of an Airbus FBW aircraft (A320 or later model) where only mechanical backup control was available?


texts: Does the canard config have radically different controls than classic config?

texts:
Classic configuration is something like the A320: wings in the middle, horizontal stabilizers at the tail.

Canard configuration is something like the Beechcraft Starship: wings at the back and horizontal stabilizers at the front (canards).

I'm just wondering if the canard config has any radically different controls for pitch? Are the directions reversed for the yoke? Are there serious re-training requirements for pilots due to some major difference? Are there bad side-effects when pitching in either direction that must be compensated for?

Note, I'm interested in large commercial jets for subsonic speeds. I couldn't find any in the canard config, so the Beechcraft was the closest example I could find.

Also, I'm asking this with traditional controls in mind...hydraulics, not fly-by-wire. I want to know if there are any radically different pitch considerations, before they are compensated by a computer.

(A related question could be for supersonic deltas, because I know some of them have canards to help stability. But I wanted to focus on subsonic flight in this question.)


texts: Are there any regulations preventing one from converting an originally cargo aircraft to ferry passengers?

texts: Are there any regulations preventing one from converting the cargo version of the Airbus A380 for passenger use?


texts:
I am trying to solve some problems on converting from LMT (local mean time) to UTC (coordinated universal time) for flight planning purposes and I have some doubts. The problem is the following:

If the LMT in Delhi (LON=85ºE) is 17:45 (5:45 PM), what is the UTC?

First of all, what I've done is converting longitude into time as follows:
$$t=85\cdot4=340\hspace{1mm} min=5h\hspace{1mm}40m$$

But then, in order to compute the UTC time, what do I have to do, either adding up this time to the current LMT or subtract it (and what is the reason)?

$$UTC=Delhi(LMT)\pm t$$

I have checked a website that allows you to convert from LMT to UTC (https://savvytime.com/converter/lmt-to-utc-india-delhi) and I've seen the solution is 11:15 PM.

However, if I add or subtract my result, it is not the same as the given in the website. I suspect it is because in India they are using UTC +5:30 and probably these equations do not contemplate that, but I want to know the opinion of the experts anyway.


texts: Is it possible to get a purely VFR job with colour blindness?

texts:
I'm 23 years old and I have red-green colour vision deficiency. I'm currently working in engineering but I have my PPL and I've been interested in commercial flying for a very long time. I've always assumed I'll be unable to get the medical needed to follow a flying career anywhere.

I wonder if there are any opportunities for flying purely in VFR, i.e. Bush flying and that sort of thing, where all flying takes place during daylight hours? Are there any airlines or other flying companies that I'd have a chance with?

Thanks, any input is really helpful :)

PS: my location is the United Kingdom.


texts: What course of action to take when having to go missed during IMC and lost comms?

texts: Under FAR Part 91 operations what course of action should a pilot take if radio communication is lost after being cleared for an instrument approach in IMC and then a missed approach becomes necessary due to inadequate visibility?


texts:
On September 25, 2011 i flew from Mexico City (MMMX) to Frankfurt, Germany (EDDF).

It was a comfortable night flight in a Boeing 747 until we started to fly over the Gulf of Mexico in holding pattern.

After some time, the passengers started to ask what was happening and the cabin crew told, that everything was fine.

After more time the flight crew told, that the United States airspace was denied to our flight and that the crew was doing everything possible to arrive to Frankfurt on time, including the request of permission to Lufthansa central for changing the route adding a refueling stop somewhere.

We threw 18 tons of fuel over the Gulf of Mexico and returned to Mexico City airport.

Mexican federal police entered to the cabin and peacefully took some passengers out.

The airplane was quickly refueled and because the long runway was under a routine maintenance, we had to wait a lot inside the plane.

People got crazy, some passengers were worried about losing connections with other airlines. On the second attempt the airspace was granted and landed in Frankfurt with around 4 hours delay.

Why can US deny airspace to commercial flights?


texts: Are task cards still used in aircraft maintenance?

texts:
I used to work for a company making maintenance software for the shipping industry. Each component, from a cylinder in an engine to the furnace has to be inspected after (e.g.) 10,000 running hours, or every 2 years, etc.

My question is:

Are task cards like the one below still used in aviation, or is there a more up-to-date way of working nowadays? (The PDF I got this from is 10,000 pages long)
What must airlines do to ensure their planes are maintained according to schedule?


texts: Is Chinese WS-13 jet engine in serial production?

texts:
The Guizhou WS-13 was being developed to power Chinese JF-17 and J-31 fighter jets.
Is its development complete?
Is it certified/finalized for serial production?


texts: Can someone/something other than the pilot trigger the ejection seat?

texts:
Let's say there was a two-person jet (take the F-15 for example) that was involved in some sort of accident in the air that incapacitated the pilot (unconscious but still alive) and left the aircraft unflyable. Could the copilot eject his fellow pilot in an attempt to save his/her life from the inevitable crash that would eventually take place?

Is there some sort of system in the aircraft that would do this automatically?

Seems like an messy problem to have. On one hand you don't want to be blasted out the windshield accidentally by your copilot or faulty computer system but on the other hand it sure would be nice to survive in the off chance you are unable to exit the plane yourself.


texts: Why is the pitching moment coefficient of an airplane said to be constant about the aerodynamic centre of an aerofoil


texts: Why is a reduction in lift called 'drag'?

texts:
Induced drag is high pressure air 'leaking' to the upper part of the wing (low pressure zone) creating a vortex which means the area of the wing tip with the vortex can't create lift. Drag on the other hand is the opposition to the flow of air. Why is induced drag called a drag when it doesn't oppose oncoming air but instead reduces wing lift?

Same thing applies to interference drag, high pressure air from the top wing of a biplane leaking to the low pressure of the wing underneath it hence reducing lift, yet it's called drag when it actually reduces lift.

So my question again is why is interference drag called a drag when in reality, it reduces lift and does not oppose oncoming air?


texts: What factors are included in the moment coefficient of a wing?

texts:
I am trying to make sure I correctly understand the moment coefficient. Both the lift and the drag coefficients vary with angle of attack and can be either positive, negative or zero. The moment coefficient pertains to the moment specifically due to the aerodynamics force (lift force on the wing mostly). The moment of a force can be calculated about any arbitrary point on the chord (or even outside of it). For a positive cambered wing, if the pole was the arbitrary point X, as the angle of attack varies (positive), the moment would vary and be negative.Is that correct? If the angle of attack goes negative, can the moment coefficient go positive?

If the pole X is chosen to be the aerodynamic center AC (25% of the chord distance from leading edge), the moment of the lift force calculated about the AC remains instead constant with varying the angle of attack.

For a positive cambered wing, I understand that there is a moment due to the lift force (mentioned above) and also another intrinsic nose-down moment (which I think it is constant for all angles of attack) solely due to the cambered shape of the wing. This intrinsic moment is nonzero when the lift is nonzero or even zero. Does the value of the moment coefficient take this intrinsic moment into account as well besides the moment due to the lift force?

Thanks.
Brett


texts: How long does it take for an FAA licence to be delivered?

texts:
Would anyone have an idea how how long it takes for a licence to be posted out.

The airmen search tells me my ATP processing was completed at some point last week. So the licence has been finalised.

Do they post the licences straight away and do they use Fedex or DHL, normal or priority?

I live in Australia. And need to present this licence at an interview in a weeks time which is why i ask. Are there means of expediting or tracking the licence in the mail?

Between the flight school and the fsdo losing my paperwork and forgeting signatures and corrections being sent to the wrong FSDO offices, its taken me about 5 months to get this licence processed. Ive missed out on some job offers already because the companies would not accept temporary licences. Id rather not miss out on this one.

If anyone has a clue, it would be most appreciated. I know fedex says its about 5 working days economy mail and UPS says 7 working days economy mail. But i have never delt with either.

Thank you kindly


texts: Which supersonic airplanes use Pitot Air intakes?

texts:
Which supersonic (fighter) airplanes use the simple Pitot Air Intakes / Normal Shock Inlets?
Two examples already seen here on Aviation.SE (one and two) are

Dassasult Rafale ($Ma \leq 1.8$)

Image Source
General Dynamics / Lockheed Martin F-16 C/D Block 30/32 Fighting Falcon ($Ma \leq 2.0$)

Image Source

Are there any more examples?


texts: Do we need to know the true track to a VOR?

texts:
An aircraft can lock onto the location of a VOR and we can see the QDM (magnetic bearing to the station) to the VOR. If this is the case, do we still need to know the true track of that route? And if so, why?

By extension, if we essentially have all we need to get to the VOR in the aircraft, why do we need to know about QTE (true bearing from the station)?

NB: I have no experience in flying a navigation flight


texts: Can roll be controlled through elevators in a fixed-wing aircraft?

texts:
In fixed-wing aircraft, roll is typically controlled through ailerons.

But I am wondering if roll could also be controlled through split, independently controllable left/right elevators?


texts: How is "information relating to the safety of flight" defined by the FAA?

texts:
14 CFR 91.183 states:

  Unless otherwise authorized by ATC, the pilot in command of each aircraft operated under IFR must report the following as soon as possible: Any unforecast weather conditions encountered; and any other information relating to the safety of flight.

This language is very vague and probably causes a lot of confusion for pilots who are studying it. Does the FAA elaborate on this concept or provide an examples or a more specific definition somewhere else? If not, what are some examples of reports ATC would expect based on this reg?


texts: Is there a practical way to demonstrate sustained flight on the back side of the lift curve without an AoA meter?

texts:
Here is a $C_L$ / $AoA$ curve that I took from Wikipedia.

The better textbooks say that a stall is that condition in which a further increase in angle of attack will result in a reduction of lift.  The point at which that transition happens is known as the critical angle of attack.  Theoretically, sustained flight is possible at angles beyond the critical angle of attack - take a look at the chart.  If the airplane can sustain level flight at point $A$, it can sustain level flight at point $B$.

Is there a practical way that I can demonstrate sustained flight on the backside of the lift curve without an angle of attack indicator?

Or to ask the question another way,

Is there a practical way to tell when an airplane has exceeded the critical angle of attack without an AoA meter?


texts: What is the most fuel efficient climb speed for a C172 SP?

texts:
Assuming ISA, sea level, no wind, max gross weight, what speed would be most fuel efficient per 1,000 ft of climb?

Alternatively, if that converges to the most fuel efficient cruise speed, when there's no time and/or distance limitation for completing such a climb, please explain why this is so.


texts: Hello I am thinking about buying a Sonex to start to learn how to fly. I want to know, if it is a good plane to learn in?


texts: Is center tank fuel required to start the 737-800 engines?

texts: I have been doing some flights with the 737-800 and when there is no fuel in the center tank, the engines won't start. Is it like that in real life?


texts: I'm told that planes can actually stall when the airflow over the wing goes past Mach 1?  Why does this happen and how do you design an aircraft to avoid it?


texts: Why were 'business jet' airliner designs so popular in the past?

texts:
Let's look at the MD-83 (was Microsoft too poor or they lazily didn't want to waste time to make it flyable in FS2004/FSX?) and the Learjet 35 (yes I used FS95/FS98 in the past).

Now, there are some "samish" things:

Engines on the back of the fuselage
Vertical stabilizers on the top of the rudder (maybe because engines take space in the back of the airliner?)
Wings on the back of the plane (let's be honest, the first time I saw that I felt like "How did this fly?" only to realize it was made in order to put CoMass near to the CoLift
Front of the plane is extremely long compared to the back of it (by back I mean the place that the wings and engine are on)
Engines are SLIGHTLY tilted to the ground

Why was this 'business jet' design so popular in the past for airliners?


texts: Why does thrust-to-weight ratio depend from max Mach number?

texts:
Why, for jet airplane design, does maximum Mach (or maximum speed) affect thrust-to-weight ratio so strictly? (as you can see for example in Daniel P. Raymer "Aircraft Design: A conceptual Approach" Table 5.3 page 80, where you can find $\frac{T}{W_o}=a\cdot M_{max}^C$, where “$a$” and “$C$” are empirical factors, for jet transport $a=0.267$ and $C=0.363$)

Just now I did notice to detail that Raymer say : "The equations were developed by the author using data from Ref 1" Ref1: i.e. the famous annual book : "Jane's All the world Aircrafts" . But anyway "maximum speed" (or maximum Mach number) in this case the maximum speed is ...the speed that the aircraft is not able to exceed  or.... the speed that is forbidden for the pilot to try to exceed because it can be dangerous? Because, if it's the first case it's more understandable; in fact, if the other parameters are fixed, with the same fixed distance, if T/W is low the acceleration is lower and so before the end of the distance, you can arrive to low speed. At the opposite if T/W is high the acceleration is higher and so before the end of the distance, you can arrive to high speed. What do you think? So, in Janes book, what is the definition of Maximum Mach number?


texts: Is the bleed air passengers breathe tapped from the engines before or after it comes in contact with fuel? And why? Isn't this unhealthy?

texts:
Passengers are often surprised to hear that the air they breathe comes from inside the engines.

This sounds unhealthy. Can you explain, why it is not ?
Is bleed air tapped (for cabin pressurization) before or after it comes in contact with fuel inside turbofan engines on passenger airliners ?
And what is the reason for either choice ?
Specifically where is the location in this diagram ? (diagrams in answers would be very welcome)

scope: This question is about the air breathed by humans inside the plane. Q11917 is about de-icing. Neither the question nor the answers in Q11917 deal with the aspect of whether the air would be safely breathable for passengers and crew. This aspect is very well dealt with in the comments and answers below. As such, these questions should remain separate.


texts: How to calculate DDM in a ILS dual frequency system?

texts:
I'm working in a project where I have to process ILS baseband signals. I have no problem obtaining DDM value from single frequency signals, nor the individual components of a dual frequency signal (DDM from clearance signal and DDM from course signal).

Now I need to merge those two individual DDM values (in dual frequency systems) to obtain an unified DDM value, similar to what Rohde equipment does (see figure below).

I've been told that I can obtain this
$\sum DDM$ value either:

As a function of individual DDM values: $\sum DDM = f(DDM_{clr}, DDM_{crs})$. But I'm not able to find the actual function $f(·)$.
Mixing clearance and course signals at baseband, so both components add up resulting in only one ILS-alike signal, and then calculate DDM from this new signal.

Are any of these methods valid? If not, how can I obtain $\sum DDM$ in a dual frequency system?


texts: How do 3d panel methods model wake-surface interaction?

texts:
I would like to know more about the general procedure used in modeling wakes for 3d panel methods.

Specifically I am looking at the effect of surfaces(fuselage and horizontal stabilizer) on the wake.

Is it better to merge wake panels with body panels or to allow the wake to clip through the body? Are there any advantages of using one over the other?


texts: What are those structures at Taif Regional Airport in Saudi Arabia?

texts:
I was looking at airports in Saudi Arabia and noticed a strange one. At Taif Regional Airport near Mecca there are a bunch of taxiways all seemingly randomly intersecting at different angles, each with a bulge in their width and a structure built in the middle of the bulge. Based on the shadows, they seem to be sunken by some amount with the structure built to roughly the same height that the taxiway is sunk. I counted at least 30 of these structures. The measuring tool on Google maps shows them to all be around 135 feet wide, and of various lengths.

I couldn't find any information about these structures or their purpose. Are they hangars of some sort? If so, why the strange design?


texts: What are those buttons pushed after thrust is set to max

texts:
If you see this video

              at 0:42 you will see both of the pilots pushed a button on the front panel.
can someone tell what that is and what it does?


texts:
I was reading some forum about funny ATC communications and one commentary was

GXXXX: Request status of danger areas X1, 2 and 4
<Pause>
London info: I don't recognise area number x124
GXXXX: My mistake I meant areas x1, x2 and X4
London info (female): Sorry, just had a blonde moment here
(assume she was new and didn't know the non appologising [sic] rule)

(source)
when referring to some thing the ATC said, apologising for not understanding some non-formal phraseology.
What is that rule ?


texts: Are there any airplanes with the Centre of Gravity behind the Centre of Pressure?

texts:
We are used to seeing a forward CG in all airplanes, from a small Cessna to a large Boeing.

I wonder whether any airplane with CG behind wing CP exists in production? Is it even possible? If so, what about its stability?

EDIT: I mean wings CP, because it is the most common definition of the airplane CP. Usually for civil aircrafts the wings produce lift, and the tailplane produces downforce to counteract wings rotation moment about CG. These aerofoils (wings and a tailplane) have 2 separate CPs and two forces in the opposite directions. I ask about the wings CP in normal wing AoA ranges (excluding aerobatics, critical AoAs etc.)


texts: Why is the use of reverse thrust not considered when calculating accelerate-stop distance on dry runway?

texts: In calculating the accelerate-stop distances, what are the possible reasons why the use of reverse thrust is not taken into account on a dry runway, while it is taken into account on a wet runway? What's the rationale behind this diffentiation, when at least as I see it there's nothing that prevents the use of reverse thrust on a dry runway for an aborted takeoff?


texts: What useful data can be obtained by using building and flying a scale model of a fighter aircraft design?

texts:
The use of scale models in the design of modern fighter aircraft seems to be rare, wind tunnel models and software is used instead. Is building and flying a scale model of a jet fighter or trainer design an out-dated practice?

NASA tested the HIMAT concept in the 1990s.

HIMAT concept.


texts: If an aircraft cannot fly above 300ft, is it an aircraft?

texts: I saw a question here that inspired one of my own. If an larger, person carrying aircraft, say some sort of hovercraft, could not fly above 300 ft would it be allowed to fly? Here in Australia, 300ft is the minimum height for an aircraft to fly over a town, so if an aircraft simply could not go any higher would it be allowed to fly at all? Or only in certain circumstances?


texts: Why are traditional knobs not replaced by touchscreens in cockpits?

texts:
Looking at this picture of an A380 cockpit I see that there are still a lot of traditional switches (meaning manual click on and off or knobs). Being technology so advanced in these days, why is it that traditional switches and knobs are used instead of having a couple of touch screens on which the various controls are placed?

Wouldn't this make it more economic as there would be savings on material and wiring? They could also be less susceptible to failures as traditional switches and knobs still rely on mechanical actions.

Another advantage I could think of is that every pilot could customise positioning of controls and switches based on his/her way of piloting. This could then be reset to a default state every time a new pilot takes over.


texts: Like transponders, can flight recorders be turned off?

texts:
I never knew much about airplanes before the tragic incident of Malaysia 370. I have been spending a lot of time on Twitter reading various articles and investigations; in one of the articles I read, they stated that unlike transponders, "black boxes" cannot be turned off.

  However, each ELT is specifically designed for each aircraft, so it
  cannot be tampered with. You also cannot turn off the black box, as it
  runs throughout the flight, recording every 30 to 60 seconds.

Is it really impossible to turn off the black boxes from within the plane?


texts: How is the ALSF-II approach lighting system built and powered?

texts:
The ALSF-II approach lighting system includes lead-in groups, a decision bar, red side bars and sequenced strobes:

ALSF-II approach lights for KRFD - Chicago-Rockford Intl (source).

Does anyone know the number and type of lights used, how they are arranged (distance and slope) and how much power is required to feed the full system?


texts: Where can I find data on the number of single propeller aircraft currently in operation in the EU and US?

texts:
Are there publicly available data for aircraft registered in operation?

Specifically I am looking for number of single propeller aircraft in US/EU, ideally with aircraft types as well. However, any useful data of this sort would be appreciated.


texts:
It may seem like a silly question, but my analogy is, some countries issue automatic-transmission-only driving licenses. Automatic transmission in this case would be the powerful avionics now available for GA aircraft.

So I think it's a valid question a non-pilot might ask.

A non-instrument rated pilot already knows how to navigate, how to use the instruments, radio, and autopilot.

So why aren't they allowed—in a properly equipped plane especially nowadays—to deliberately (with permission) fly into IMC, or file an IFR flight plan?

(Image source)


texts: What is the effect of power extraction on turbofan compressor and turbine maps?

texts:
Effects of Power Extraction on Turbofan Compressor and Turbine Maps

The two diagrams below show the effects of shaft power extraction (shaft power offtake / shaft power off-take for the propulsion of accessories such as fuel-/hydraulic-/oil-pumps, generators etc.) on a high-bypass turbofan engine at a flight altitude of $H = 11km$ and a speed of $Ma = 0.8$, calculated with GasTurb 12:

Effects of Power Extraction on the Operating Line (Blue)

Why are the operating lines (blue) of both the compressor and turbine shifted to the left towards the surge line?
In particular, why does the non-dimensional corrected mass flow decrease, while the pressure ratio stays approximately constant?
The same question from a different angle: Why does the pressure ratio not decrease at a constant mass flow?


texts: Does a 709 ride mean the end of my career?

texts:
If I'm required to do a 709 ride following an incident where the plane went off the end of the runway but it wasn't damaged and no one was hurt, what effect does it have on my future as a pilot?

I'm looking to go into commercial aviation (I'm currently a CFI working on hours) and am specifically wondering about how having it in my record will affect interviewing for regionals.


texts: Which FAA regulations require passengers to comply with flight crew instructions?

texts:
Recent unfortunate news headlines prompted a quick search for the almost universally un-cited regulations governing passenger compliance with flight crew, and all I could find were regulations that seem to be quite specific in application (14 CFR 125 - interference, etc.).

While it makes sense that passengers are expected to comply with reasonable requests, one would not expect the law to require compliance with unreasonable requests unrelated to safety, or requests that actually endanger passengers.

So, for example, if a crew member requests that a seated and non-disruptive passenger leave a plane for purely commercial reasons unrelated to anyone's safety, is there a law or regulation that supports this for US carriers?

Again, I expect the answer is "yes," but am interested in the legal basis for it, and do not think the self-serving fine print on an airline ticket qualifies.