texts: Why are yaw rate and pitch rate obtained by these equations?

texts:
I am reading "Introduction to Aircraft Aeroelasticity and Loads" by Jan R. Wright and Jonathan E. Cooper.

The book said: In steady bank turn (as shown in picture below), The rate of turn is given by:
$\omega_{turn} = V/r $  (I understand this)

And so the aircraft experiences steady yaw and pitch rates given
by':

$n_{yaw}= \omega_{turn}cos \phi$

$q = \omega_{turn}sin \phi$

I don't understand 2 equations above. I think the yaw rate would be equal to the turn rate and the pitch rate is zero.


texts: How do I fix a slipping throttle friction lock in my C182?

texts: The throttle friction lock in my C182 works poorly in cruise, it slowly eases out to a lower power setting. What can I do to make it better? I've attempted to turn the lock nut harder but without result.


texts:
Planes use skis to land on ice/snow runaway.

How can the plane brake in such conditions?

Friction must be limited to allow takeoff and aerodynamic braking are not the main contributors to the deceleration on wheel landings.

Image source


texts: Why is it hard to see G1000 with sunglasses?

texts:
I got checked out in the G1000 172 at my flight school just so I could schedule to fly when the two steam gauge 172s were booked. I'm very impressed by the G1000, but I can't wear sunglasses when I fly the NAVIII. This is with the avionics dial on the lighting panel turned all the way up.

Does anyone else have this problem? Is it my sunglasses?


texts: From how far away are the navigation lights of a large airliner typically visible?

texts:
I live about 22 miles away from one international airport in the UK, and just over 30 miles away from another.

When I spot aircraft lights at night and check for corresponding aircraft on flightradar, I'm surprised to see that they seem to belong to aircraft making approaches to land at these airports - which got me thinking - on a clear night, from how far away are a large aircraft's navigation lights typically visible? (I'd be interested in answers relating to distance when viewed from the ground and in the air).


texts: What is this squawk 7777 target at an altitude of 62,700' over Germany?

texts: Can anyone shed any light as to what this is (circled in white)?


texts: What is the relationship between the code of an Area Control Center (US) and associated Flight Information Region?

texts:
From the wiki page, what I understand is

  an Area Control Center (ACC), also known as a Center (or in some cases, en-route, as opposed to TRACON control), is a facility responsible for controlling aircraft en route in a particular volume of airspace (a Flight Information Region). In the United States, such a Center is referred to as an Air Route Traffic Control Center (ARTCC).

My question: Is ARTCC code different from the ICAO-FIR code? Or are there anomalies?

For example, here's a NOTAM in the FAA site. AT the bottom, under the headline Other Information, the ARTCC code is given as ZDC. Can I safely assume that the ICAO-FIR code would be KZDC for that NOTAM?


texts: External recordable CCTV, a third black box

texts:
I wonder if aircraft, and especially large commercial ones, should be fitted with external recordable CCTV. This would enable the crew to perform visual pre-flight checks from the cabin that would not normally be possible to ensure that flaps, rudder etc are actually working and to full extent, but also in case of emergency, would enable the crew to visually check the entire aircraft for the same, and for engine fire, for trauma etc at a glance. Valuable time can be wasted trying to figure out what has actually happened. This would also help prevent errors such as shutting down the wrong engine in case of fire. The recordable aspect would also act as an extra "Black box" in case of tragedy  and would no doubt be a great aid to and speed up Crash Investigation.

This system has been employed for many years in the bus and lorry industry, but mainly to help determine blame in case of accident.


texts: Where and when would a 737-700 be taking off at an altitude of 19 kft?

texts:
Another question triggered by reading the 737 technical site; according to this section of the page on the 737's pressurisation system, the 737-700 comes with an option that allows it to safely take off and land at altitudes of up to 19 kilofeet AMSL (my emphasis):

High Altitude Airport Operations System
Is a customer option for operations into airfield elevations of up to 10,000ft (all NG), or 13,500/14,500ft (-6/700 series only). Changes include: Addition of high altitude landing selector switch to transfer to the high altitude mode, cabin altitude at warning horn activation is increased, an extra hour of emergency oxygen (bottles stored in aft cargo compartment), 10 minute take off thrust if engine inop; winglets, carbon brakes and fwd Cof G options are recommended. For the 737-700 the takeoff envelope is increased to 19,000 ft & 0.50Mn. The option is usually taken with increased MLW, carbon brakes and RNP

Yet even the highest-altitude airport in the world - Daocheng Yading (DCY/ZUDC) in western China - is only 14,472 feet AMSL.
What justified providing the 737-700 with the ability to operate from a completely hypothetical airport over 4,500 feet higher than any existing in the world?


texts: What are common airline crew titles and positions?

texts: I realize that airlines can operate with different numbers of Pilots and Flight Attendants, depending on the route, aircraft and length of flight (EET). Which are the types of crew members that an airline can have, with the correct titles? I've heard about captains, master captains and cruise captains, but how can I identify them during the flights?


texts: What if traffic should give way to me but doesn't appear to be?

texts:
Let's say I'm flying a GA aircraft VFR, and I don't have TCAS or similar. I see another aircraft on a converging course, and it must give way to me. (Suppose it has me on its right.) It doesn't appear to be changing course to avoid, so what should I do?

Obviously I shouldn't just wait for us to collide, but at the same time, I don't want to take action that will negate its avoiding action. (e.g. If I climb to avoid, and he climbs to avoid because he was expecting me to hold course, we will both still collide.)

The question seems to relate mostly to uncontrolled airspace, but I'd appreciate an answer that also covers controlled airspace possibilities.


texts:
So, currently my team and I are working on a glider project for our senior design.
The design we've come up with causes XFLR to crash for some unknown reason (the issue seems to be at the root airfoil which is wedge shaped). What I would like to know is if there any viable alternatives to XFLR for airfoil and aircraft analysis that won't crash like XFLR does.

Edit: So the main goal of this project is develop an autonomous system to be used in hypersonic glide vehicles. While obviously we're not going to be making a hypersonic glider, my professor is insistent that it at least looks hypersonic. It needs to be able to glide for about 2000 feet after being dropped from a height of 300 feet.


texts: How far should commercial jets be from each other when on the runway or while departing?

texts:
Does anyone know how far should a commercial jet (787,777,etc...) be away from each other in runway or in process of taking off?

Are there public resources that I can look up?


texts: Can a wind tunnel simulate airflow when a vehicle goes around a curve?

texts:
In real life, airflow in a turn is curved, how does a wind tunnel simulate this condition?
If we just yaw the test object at some angle in wind tunnel, do we simulate the airflow in correct way?


texts: Could abrupt flight controls input cause damage in these circumstances?

texts:
I went flying yesterday with a friend in my 1972 Grumman AA-5. She's a good copilot for someone who doesn't know much about flying. I showed her how you can pitch up and down, cause 0G, and float, which is fun. I did that when she was stretching in an awkward position to surprise her, but she took revenge and did it quite hard and abruptly while in cruise around 105 MPH without turbulence, which made us hit our heads on the canopy.

We probably didn't have our seatbelts tight enough. But could this have structurally damaged the plane? Should I tell my mechanic? It behaved  normally afterward.


texts: How do you request a "pop up" IFR clearance?

texts: If you are flying VFR into deterioration weather conditions and would like to continue the flight under IFR, or you would like to climb to a better altitude but are restricted by a cloud layer, what is the easiest way to go about requesting and instrument clearance.


texts:
I remember when the first AirFones were put into service in 1990s and marveled at who would be rich enough to pay $7/min for air to ground phone service.

Even though every seat eventually had an AirFone, I cannot once recall seeing one in use (except in movies) in twenty years of flying (in economy).

I know they're being pulled out now, but did AirFones ever make a profit? Who paid for their installation, was it the airlines or did GTE etc pay for everything?


texts: Is flying a UAV via a VR controller (e.g. Oculus) legal in the US?

texts:
I've heard claims that flying a UAV using a Virtual Reality headset (for example, the oculus rift) is illegal per FAA regulations.

Is this true? I cannot find any definitive answer either way.


texts: First time passenger flight by two pilots?

texts:
In this video, the captain proclaims after take-off:

We were nervous about this, but takeoff went smoothly

It was his first passenger flight in the A350, but still... not exactly what I would want to hear as a passenger. This got me thinking, does it ever happen that two pilots take their first passenger flight on a given type together, or will it always be the case that if it's someones first time, the other pilot will have X amount of hours on that type?


texts: Can some IAFs be skipped if more than one IAF exists?

texts:
Take, for example, this FAA official IAP plate (ILS RWY 13L CAT II JFK). Its Initial Segment consists of more than one Initial Approach Fix (IAF): COVIR, KMCHI, and BUZON. As far as I can interpret this, when an aircraft enters from the en route structure, it is obliged to follow the route COVIR → KMCHI → BUZON → TELEX etc.

My question is, is the aircraft supposed to follow this particular route or, depending from where it comes, it can "skip" e.g. the first Initial Approach Fix, and follow the route KMCHI → BUZON → TELEX (instead of COVIR → KMCHI → BUZON → TELEX)?

Also, if the answer is yes, does that mean that it can even ignore all the IAFs and enter Intermediate Segment directly, provided that this serves its purpose better?


texts: Why do we refer to "power" for turboprop engines and "thrust" for turbojet/fan engines?

texts: In jet engines, I read that thrust is related to the fuel flow rate, whereas in turboprop engines power produced is related to the fuel flow rate. What is the reason and brief math behind this?


texts: The cockpit can hold one person, is smaller than a compact car and as narrow as a motorcycle. What kind of plane is this and how hard would it be to fly?


texts: Who manages air traffic during Red Bull air races?

texts:
I'll preface this by saying I'm not a pilot so I don't know much about Air Traffic Control.

How does Air Traffic Control work for Red Bull air races? Does:

(1) each plane taking off need to contact the local airport's ATC and let them know what they plan on doing/request permission for it, or

(2) do the event organizers schedule a block of time and airspace with ATC and take care of managing that block by themselves?

The latter seems feasible from my (non-pilot) perspective:

there's only one plane at a time on course (easy to manage)
it's a pretty well defined area that they'll be staying within.

It would help the event by:

perhaps allowing some of the long-range communication systems to be removed from the airplanes (reducing weight - useful for racing)
give the pilots fewer things to think about prior to their run on the course
transferring the control of take-offs and landings to the organizers makes it easier for them to stay on schedule

I think there would be advantages for them to do it the second way, and I think it would be technically possible to safely do it that way. However, it's not what I think is "standard procedure" and I wonder if they strayed from standards for their events' organization.

So are they doing it the first or second way? If they're doing it the first way, why? It seems inefficient, could they do it the second way (legality/regulation -wise)? Did I miss something that would make method (2) more trouble than it's worth? Or maybe they're doing it some other way I didn't think about?


texts: Why do anti-ice systems on airplanes with automatic ice detectors still need to be manually selected on?

texts:
As even minuscule amounts of ice accumulation on aircraft can cause tremendous loss of lift, increases in drag, decreases in engine thrust, and/or flight-control impairment, some method of detecting ice is essential for safe flight, even for aircraft not certified for flight into icing conditions.  Various methods exist for doing this, ranging from examination with the Mk. I eyeball (for many light general-aviation craft, and even some larger planes) to sophisticated electromechanical systems utilising vibrating probes which change frequency when made more massive by ice accumulation and set off an alarm in the cockpit.
For aircraft not certified or equipped for flight in icing conditions, the detection of ice lets the flightcrew know that they need to get out of the ice ASAP.  For aircraft which can fly in ice, it signals the need to activate the aircraft’s built-in deice/anti-ice systems; these come in three main varieties (melting the ice using hot engine bleed air, melting it with resistance heating from electrical heating elements, and mechanically breaking it off with pneumatically-operated deicing boots), but all of these still need to be manually turned on by the pilots, even for aircraft that can automatically detect icing.
Given the potentially-catastrophic consequences of allowing ice to accumulate unchecked on an airframe, and the ease with which a flightcrew (especially if fatigued or already task-saturated) could overlook or forget about an ice warning, why don’t aircraft with automatic ice detectors and built-in anti-icing link the two together, and have the ice detector automatically turn on the anti-ice system when it detects icing?


texts: What is this device on the nose of a Bombardier Global 6000?

texts:
What is the circled object?

(jetphotos.net)


texts: During which part of the flight the effect of air resistance is more important?

texts: Her teacher asked this question to my niece (8 years old)? However I couldn't find a solid answer either. In which part of the flight, the effect of the air resistance (drag) is more important? Takeoff, cruise, descent or landing?


texts: Why is deploying speed brakes not recommended with the flaps extended?

texts:
I read this in the normal procedures section of the A320 FCOM. Why is it so?

  When the speed brakes are deployed, extending the flaps beyond FLAPS 1 may induce a slight roll movement, and in calm conditions a small lateral control asymmetry may remain until disturbed by a control input or by an atmospheric disturbance.


texts: I can't find a list anywhere (other than regular flights), but I am really interested, which airports have ever handled an A380 flight, including all one-time visits or emergency landings.


texts: What do I look for when getting a PPL at a college or local school?

texts: I am interested in getting a private pilots license and I know I can go to a near by airfield to get one. However I would like to know if anyone has received one through college and if it would be best just to wait until then? The cost at the airfield near me is around $12,000 but i have not found a cost for getting one in college.


texts: How are fuel injectors in a jet engine monitored to detect malfunction?

texts: As far as I know in a car engine the ECU can adjust fuel mass flow through every injector. I don't know the exact algorithm but probably engine roughness is monitored. Of course this is not possible in a jet engine. What will happen if an injector starts to malfunction? I assume it will be quite difficult to detect and a slight decrease in maximum power will appear. But engines usually are not run at full power? Can this be dangerous when maximum performance is needed (like engine failure at V1)? How are injectors tested in engines with mechanical fuel control? Can FADEC monitor fuel injectors?


texts: How do airlines choose what food to serve?

texts:
I'd imagine there are probably reasons behind the choice of food that airlines serve, and I'm wondering what those reasons are?

I guess that Air India probably serves more curries than American Airlines, but what other considerations are taken into account? Presumably weight is one.


texts: What programming languages are used for equipment onboard aircraft?

texts:
Generally speaking, What programming language is used in aviation for (ATC Radio, Radar, ILS, Auto-pilot and on-board avionics)?

Is there a standard enforced by ICAO?
Does every plane manufacturer use the programming language they like as long as it's reliable and it goes through testing?

I remember watching a documentary on YouTube last year about aviation and it said something about the EU, after WWII, started making standards for aviation systems inside Europe.
I will link the video if I can find it


texts: Time of flying from Toronto to Philippines

texts:
Please I would
Like  to know how many hours I will be flying
Across the ocean . I will be flying on an aircraft 773 boing 777.


texts: Is it always required to calculate the fuel for an IFR alternate?

texts:
I was asked to plan a cross country flight from KTMB (Miami Executive Airport) to KTPA (Tampa International Airport). After doing all the planning, I realized I needed to calculate the fuel for an alternate airport.

According to 14 CFR 91.167, fuel is required from departing airport to intended destination airport, plus from intended destination airport to alternate airport, and another 45 minutes of flying at normal cruising speed.

In 1-2-3, if weather forecasts tell that 1 hour before and 1 hour after the ETA, the ceilings would be less than 2,000 feet and less than 3 statute miles visibility, I need to file an alternate airport.

But if the forecasts tell that at KTPA, the weather conditions will be better than that, would I still be required to calculate the fuel for an alternate?

If the conditions are worse than that, then how would I calculate the fuel to my alternate, which I chose to be KSRQ (Sarasota–Bradenton International Airport). Do I need to do again the SID at KTPA, then enroute and then STAR and approach at KSRQ, or just a direct flight?


texts: Can we trade some efficiency to curb high-altitude emissions?

texts:
Considering our problematic issues,

Emissions at high altitude
Contrails
~10,000 premature deaths per year from airline emissions

This is an area of concern where it's worth asking some stupid questions.

What would happen if a hose was attached to the core/hot nozzle of a turbofan, diverted to storage on the body? Could it still be efficient 'enough' (assuming a highest possible bypass ratio) to compress and carry some of that carbon dioxide to the next airport?


texts: Why in certain airports the windows are blocked while others not?

texts:
In certain airports, like the T1 of MMMX the windows are blocked or semi-blocked

while in others are not (MMGL)

I understand this could be done to avoid debris hit the windows, but then why?


texts: As a Canadian teenager hoping to become a commercial pilot, I'd like to know how hard it actually is to live the life of a pilot. I've heard from some people that the hours can be pretty gruesome, which is obviously a little off-putting. Are you able to maintain a relationship?Are the hours off-duty at home plentiful enough or few and far between? Is the pay worth it? Do you get vacation days and/or sick days like any other job? Any details on the life of a pilot and whether or not you'd suggest it would be much appreciated.


texts: How should I safeguard my FAA certificate number?

texts:
The FAA’s Search Airmen Certificate Information reads in part

Personal Information
We do not display your SSN, certificate number, or date of birth. We will display a releasable address in accordance with the Aviation Investment and Reform Act for the 21st Century (PDF). We display medical information based on FAA’s Civil Aerospace Medical Institute (CAMI) medical records. If the medical dates are incorrect, please contact CAMI at (405) 954-4821.

Airmen Certification Frequently Asked Questions contains the same intended exclusions.

Do you display my certificate number on the Internet?
We do not display your SSN, certificate number, or date of birth on the FAA website.

The U.S. Department of Transportation publishes an FAA Privacy Impact Assessment – Airmen/Aircraft Registry Modernization System (RMS) notes that Social Security Numbers were used in the past for certificate numbers, but policy has changed.

Personally Identifiable Information (PII) and RMS
To handle airmen certifications and aircraft registrations, FAA requires PII about airmen and aircraft owners/registrants. With this in mind, RMS may include or collect the following data on airmen and/or aircraft owners and registrants, either for authentication or certification requirements: Name, Date of birth (airmen only), Social security number (airmen only), Driver’s license number, passport number, or government ID number, Physical Description (height, weight, hair and eye color, sex, and citizenship), Address (airmen only), Medical records (airmen only), Certificate number (airmen only). In the past, RMS used an airman’s social security number as the certificate number. FAA is now changing that practice, developing unique certificate numbers not affiliated with social security number. During this change, airmen can request, online or offline, that his or her social security number not appear as a certificate number. For an individual’s PII to be included in RMS, that individual must be associated with an airmen or aircraft certificate or application.

It is clear that for airmen whose certificate numbers match their SSNs, adhering to best practices and remaining clear of practices to avoid (cf. recommendations from the Social Security Administration) are wise courses of action, primarily to reduce the risk of identity theft and fraud.
To get credit for FAA WINGS training hosted at AOPA’s Air Safety Institute, certificate number is a required field—but also one whose value ASI is careful to note that they do not store and that they pass with some level of encryption protection.
So many legal disclaimers raise red flags. What are the risks of disclosing an FAA airman certificate number? Is all the handwringing due strictly to the fact that some certificate numbers are also Social Security Numbers and nothing else? How should I protect my certificate number, which differs from my SSN?

Note: All quoted passages were retrieved from the linked resources on July 26, 2015.


texts: Are there any civilian powered-lift aircraft besides the AW609?

texts:
I was looking at the difference between rotorcraft and powered-lift and every example I saw was a military application (Osprey or Harrier or F35)

The FAA defines powered-lift:

  Powered-lift means a heavier-than-air aircraft capable of vertical
  takeoff, vertical landing, and low speed flight that depends
  principally on engine-driven lift devices or engine thrust for lift
  during these flight regimes and on nonrotating airfoil(s) for lift
  during horizontal flight.

I was wondering if there were any small, personal powered-lift aircraft that one might get their private pilot license in the way people get a ASEL certificate in a 172.

I know there is the AW609, but that is targeted towards the business market with a very specific niche.


texts: Is there a real temperature change along a streamline when its velocity changes?

texts:
Stagnation enthalpies are given as

$H_T=H+\frac{v^2}{2}\ $

Along an adiabatic inviscid steady flow streamline Stagnation Enthalpies are said to be constant.

$H_{T1}=H_{T2}$

$H_1+\frac{{v_1}^2}{2}\ =H_2+\frac{{v_2}^2}{2}\ $

$H_1-H_2=\frac{{v_1}^2}{2}\ - \frac{{v_2}^2}{2}\ $

$H_1-H_2=\frac{{v_1}^2-{v_2}^2}{2}\ $

Stagnation temperatures are  also constant

$T_0=T_1+ \frac{{v_1^2}}{2CP}$

$T_0=T_2+ \frac{{v_2}^2}{2CP}$

$T_1+ \frac{{v_1}^2}{2CP}=T_2+ \frac{{v_2}^2}{2CP}$

$T_1-T_2= \frac{{v_1}^2}{2CP}- \frac{{v_2}^2}{2CP}$

$T_1-T_2= \frac{{v_1}^2-{v_2}^2}{2CP}$

In both of these equations there is derived a notion of a static enthalpy and static temperature at a point of interest along a streamline. These can be different by the value of the flow velocity v

This is stated to be applicable to compressible and incompressible flow

Is it correct to say that there is a real temperature change $T_1-T_2$ along a streamline when its velocity changes?


texts: In the Aircraft Flight Manual of the Bombardier CRJ700, the Minimum Flight Weight is listed as 42,000lbs. What is the meaning of Minimum Flight Weight?


texts: Where do I start learning about Avionics programming?

texts: I am a student in his last semester going for a B.S. in Computer Science. I would like to eventually transition into the space exploration industry (NASA, SpaceX, Boeing, Lockheed Martin, etc). I know nothing about avionics and i would like to learn more about the subject, specifically the software side. I have found little information online. Please give me reference material (books, websites, etc.) to learn about this area. Your point of view and additional information is strongly welcomed.


texts: What closed-cockpit biplane is this model modelled after?


texts: Is it fact or fiction that Ashgabat control tower is misplaced?

texts:
It's often written that the construction of Ashgabat International Airport was sabotaged by the aesthetic whims of the country's late leader, Saparmurat Niyazov.  The story goes that Niyazov, presented with the architectural plans for the airport, insisted that the air traffic control tower be moved to the "wrong side of the runway".  He supposedly overruled the better judgment of the airport planners because he thought the airport would look better that way.

In the West, Niyazov is widely considered to have been an eccentric and megalomaniacal dictator, thanks in part to stories like this.  While many of these stories are undoubtedly true, others have been shown to be exaggerations or misinterpretations.  I'd like to know whether there's any truth to the story of Ashgabat's air traffic control tower, or if it's just another one of the false but plausible-sounding rumours cooked up to further mock Niyazov.  So my questions are basically as follows:

Is there, in fact, any significant problem with the placement of the air traffic control tower at Ashgabat International Airport?
If the tower is poorly placed, what specific problems does this placement cause for air traffic controllers and airplane pilots, and how do they work around these problems?
If the tower is poorly placed, is there any reliable evidence that this was a result of Niyazov's direct personal involvement?  If there isn't, what's the earliest known appearance of this claim?


texts: Is a lapsed Advanced Ground Instructor certificate acceptable to use as proof of FOI when taking CFI initial?

texts:
I have an AGI certificate that I haven't exercised the privileges of in the preceding 24 calendar months.

When I initially got the AGI, I had planned to take my CFI almost immediately but didn't. I'm having trouble locating the regulation that shows that since I have my AGI, I don't have to re-take the FOI written to complete my CFI.

What regulation states that this is possible?


texts: What airfoil simulation software is suitable for a cut trailing edge?

texts:
I'm looking for a way to simulate airfoils used to reduce turbulence.
airfoiltools.com already does this a long way.

However I have width and length limits, and I'm interested in comparing full profiles with profiles that are virtually longer but cut where the trailing end meets the boundary.

Can CAESES or SimFlow do this without too steep learning curve? (I'm a complete newbie.)

(Specifics: Chord 30 cm, width 25-30%, Reynolds number 1,500,000, NCrit 9, 50-70m/s)


texts: Can you identify those parts (sensors), on test aircraft and the purpose?

texts:
I have seen many photos with those sensors attached to the test aircraft, Can you provide why they are used and what do they measure?

Here is another example on SuperJet:


texts: What fighters have both 1 & 2 engine versions?

texts:
Northrop originally built the F-5 "Freedom Fighter" (and T-38 "Talon") with two engines. Later it was re-fitted with a single F404 engine from the F/A-18, re-designating it the F-20 "Tigershark" to avoid confusion. The first F-5A and T-38 flights took place in 1959.

[Addendum: There is no real contradiction, the T-38 "Talon" was a two place trainer version of the F-5 "Freedom Fighter". Most aircraft don't re-designate between one and two seat versions, but Northrop or the military did in this case.] See the history of the F-5 YouTube Video

"Though the USAF had no acknowledged need for a light fighter, it did procure roughly 1,200 Northrop T-38 Talon trainer aircraft, which were directly based on the F-5A." https://en.wikipedia.org/wiki/Northrop_F-5

"The F-5G was an advanced single-engined variant later renamed the F-20 Tigershark." https://en.wikipedia.org/wiki/Northrop_T-38_Talon

Have any other fighters (world wide) offered a fighter with one and two engine models?

Twin engine F-5 "Freedom Fighter".

Single engine F-20 (F-5G) "Tigershark". Wikipedia


texts: Can a plane be IFR certified, but not allowed in IMC?

texts:
The Evektor Harmony LSA & RV-12 SLSA have all the necessary equipment to be certified for IFR flight, except the only engines allowed for purchase are the Rotax 912 ULS & iS. These engines are not allowed in IMC.

Question: Can these planes be certified for IFR, despite the IMC limitation?

if no, can they be used for training for one's instrument rating and for the instrument rating checkride?
if yes, then if one were to be flown into IMC, would be this be a legal violation or a warranty violation?


texts: How do airports manage gate assignments for aircraft?

texts:
Today, some companies like Delair, SITA and INDRA provide airport Resource Management Systems (RMS) for gate allocations, which show information as a Gantt Chart.

I know that air traffic controllers use a flight progress strip to track flights under their control, but how was parking managed in the past without today's RMS solutions? What do dispatchers use for gate management? If it's manual, what is the process?


texts: Are the military tilted-thrust aircraft in the film Avatar feasible?

texts: As full-scale aircraft or as models / UAVs / drones?  Is anyone working on making these real or are they fundamentally flawed designs, or needing new materials to be invented?


texts: What kind of flight-control redundancy does the Tu-204 have?

texts: The Russian Tupolev Tu-204 and variants are reported to be digital fly-by-wire. Are they quadruplex redundant? Do they have manual or analog back-up systems?


texts: Are there diversion points for southern Pacific great circle route flights?

texts:
At first I wasn't even sure if any airlines flew southern Pacific great circle route flights, but it looks like Qantas (QFA27) operates a flight between Sydney and Santiago, Chile.

For northern Pacific greate circle routes, you are flying near Canada/Alaska and then Russia for most of the flight, so you have some airports you could potentially divert to if an emergency arose. I've search online for more details about how this works for these flight, but haven't had much luck finding information.

Are there any point on the southern Pacific great circle route for flights to divert to? Or is there not really any backup plan if something goes wrong? Are there specific requirements that must be met for an aircraft to fly this route?


texts: What is the distance between 2 adjacent waypoints?

texts:
I am working on an en route air traffic control system. For the application I plan on allowing the user to plot the position of a few waypoints on a square region which is 100 miles in length and width. The aircraft will then follow a route which passes through the relevant waypoints. Therefore, I would like to know whether there is a general estimate for the distance between 2 adjacent waypoints so that I could have rules for where the waypoints can be plotted and how many of them can be plotted in the whole region.

Thank you very much for the help!


texts: Why did this aircraft fly in this pattern over Southern Italy?

texts: Why would an aircraft fly in the pattern shown in the image below? The location is Southern Italy.


texts: What is the physical explanation for the formation and position of stagnation points on an object moving in a fluid?

texts:
I have some questions regarding the stagnation points, both on an airfoil and on a generic object.

What is the physical explanation for the formation of two stagnation points on an object moving in a fluid (e.g. a cylinder)?
Why in potential flow with zero circulation the rear stagnation point is located above the trailing edge of an airfoil (and not below)?

Does the Kutta condition hold even on flatback airfoils like this one? They have a truncated trailing edge, so I think the "infinite velocity" problem would still arise (in theory, of course).
Where is the rear stagnation point located? The image below gives their approximate position, but it's not clear where the rear stagnation point is.

(source)


texts: Is aviation software translated into the users' native language desirable over English?

texts:
I want to build some software containing information about aircraft, like a logbook. Nothing related with avionics.

I know that default language in the aviation industry is English, but in the case of online software, could professionals be interested in using an online logbook or MRO software showing in another language besides English?


texts: Is the Bede BD5 actually a tandem wing airplane, and not a mono wing?

texts:
Is the Bede BD5 a tandem wing airplane, and not a mono wing?
The following picture (Source: Wikipedia.org) shows a Bede BD5 with a high angle of incidence on the horizontal tail, estimated at about 5 deg.
Being a rear engined airplane ( estimated fuel and engine north of 150 lbs) and with the main wing close to the pilot(150 lbs+), it seems the CG would be aft of the main wing.
Does this mean the vertical tail was used to generate some of the total lift (estimated at about 30%),in straight and level flight, thus making the BD5 a tandem wing, and not a mono plane?


texts:
After several weeks of being grounded due to low clouds, I was looking forward to the cool air, clear skies, high pressure and light winds that arrived this morning as forecasted. However, there is an AIRMET over the whole region for moderate turbulence, so I’m stuck on the ground yet again staring up at a sky that looks like perfect VFR flying weather but somehow isn’t.
The FAA books tell me that turbulence is due to unstable air, but I can’t piece together why it’s unstable today or, more importantly, how I could have predicted it. Which charts or other data should I be looking at, in particular days ahead of time so I know when is best to schedule a flight?


texts: Does adding more engines to commercial aircraft increase safety?

texts: For example, the Boeing 747 has four engines, whereas the Boeing 737 has 2. Does this means that the Boeing 747 would be safer if one of the engines fail?


texts: Where to find the callsigns of the en route controllers?

texts:
I am looking for the callsigns of ATC upper information region (UIR) controllers on a flight from Frankfurt EDDF to Seattle KSEA. According to the flight plan, the UIRs crossed are:

EDDV (Hannover)
EHAA (Amsterdam)
EGTT (London)
EGPX (Scottish)
EGGX (Shanwick)
BIRD (Reykjavik)
CZEG (Edmonton)
CZVR (Vancouver) and
KZSE (Seattle).

First, where can I find charts and information on the sectors within a UIR?

Second, does each sector have a different callsign, or are callsigns coupled to the UIR? For example, EGPX Shanwick will probably have multiple sectors, will the callsign be always Shanwick control? If they are UIR-dependent, what are the callsigns of the above-mentioned UIRs?


texts: Would knowing the exact weight that has been loaded on a commercial plane and it's distribution be useful?

texts:
There's been a bit in the media about weighing passengers in order to get more accurate take off weights for commercial planes.  I'm guessing the delta between a heavy set of passengers and a light set might be 3000 kg.  If there was a cheap way of determining the weight that has been loaded onto a commercial jet would it be valuable out not, given this level of weight difference? I am after an actual cost. What is the cost of an airliner carrying the
additional fuel required by current rules if it assumed the overall mass estimate is 3000kg too high throughout its life? It won't be using that fuel but it will have to carry it.


texts: Why does the Canadair Regional Jet still use CRT screens?

texts:
All the CRJ aircraft from the 100 up through the new 1000 use the antiquated CRT technology for the main primary and secondary displays as well as the ED1 and ED2 displays.

Aren't flat screens a more modern, cheaper and reliable technology? Why aren't there flat screen retrofit units for the older aircraft or flat screens in the newer aircraft?


texts: What would cause a non-zero indicated airspeed reading on the ground?

texts: What kind of failure would cause an indicated airspeed of say 200 knots on the ground (stationary)?


texts: Who has the final authority over sidesticks?

texts:
I’m wondering what would happen if - for some reason - the pilot and his copilot were fighting over the control of an Airbus with their respective sidesticks.
Does the pilot gets the final word ? Does it works like in a traditional system, where the strongest one takes it all, but through force feedback ?


texts: How far would a landing Airbus A380 go until it stops with no brakes?

texts: If an Airbus A380 lands with all brakes disbled, including reverse thrust, wheel brakes and any other measures it has to stop or slow down. Then how long would it take it to reach a complete stop.


texts: How did night fighter aircraft manage to shoot down their foes in World War II?

texts: I know that those plane had radar to acquire an approximate location of the enemy, but how did they spot them after that? You need to be accurate when you try to shoot down an enemy plane, and deflection can be tricky, even at close range. So how did pilots aim in those conditions?


texts:
I was just reading up about different methods of reducing drag through the different wingtip designs when I come across Hoerner Wingtips.

So after some research, I have two questions.

According to this article on pg 1, it states that "The convex underside accelerates the speed of the air passing under the tip to a velocity more equal to that of the air flowing over the top of the tip, thereby creating streamline flow." How exactly does acceleration of air occur just by having a convex underside?
As we can see, the effective wingspan using Hoerner Wingtips can be increased without increasing geometric wingspan.

How does a Hoerner Wingtip enable vortices to be generated further away, therefore increasing effective wingspan?

Thank you! :)


texts: How can I find traffic patterns that pass over my house?

texts:
I live in Atlanta, GA well north of the airport and typically there is very few large, commercial aircraft that pass overhead. But there is an on-going security issue at the airport today and there are some really low-flying commercial jets passing from east-west over my house at altitudes that look like they would be on final approach (if they weren't 40 miles north of the runways anyway). There is a military airport near by and we frequently have C-130's landing but they don't come from that direction.

So I really have no idea what those planes were doing or where they were going, and in the 5 years I've lived here there have never been commercial planes that flew that pattern. At another place I hang out, close to the airport, I've noticed that air traffic passes over when there are storms at the airport.

I would imagine this is a "something is wrong at the airport" pattern as opposed to a normal operating pattern, and it may even be something that was specific to that particular aircraft for some reason.

Is there any way to look up what patterns would pass over a given location under what situations? Or more likely -- how can I look up what patterns are around an airport and how those patterns change with conditions (weather, emergency, traffic, etc)?


texts: How low was the Hong Kong Kai Tak landing approach over the city?

texts:
Hong Kong's Kai Tak approach was famous for its unique approach, including the "checkerboard" and its low altitude when passing over Kownloon.  The latter has been memorialized in innumerable photos and film clips.

At what altitude did landing aircraft typically pass over the city on this approach?


texts: How much clearance is provided when taking off over a 50 foot obstacle?

texts: When performing a takeoff over a 50' obstacle, how much clearance is provided between the obstacle and the aircraft and where can that be found?


texts: What is the purpose of the box between the engines of an A-10?

texts:
There is a curious box between the engines of an A-10. It's seems rather rudimentary, like an afterthought, although it was present on the prototype.

I've found a few cutaways but this part is hidden. I'm fairly sure that at least the front is hollow, so perhaps related to an APU. The question is, what is it for, and why, even in the context of the somewhat inelegant A-10, why so unrefined?

source: savasucakalari


texts:
Please give a basic explanation of how commercial aviation traffic is routed for readers without any foreknowledge:

Can commercial aircraft only follow airways like cars on highways ?
Or are airlines free to choose a straight line between airports (excluding probhibited and restricted airspace) ?
Or is it a mix of both ? If so:

When must airliners follow airways ?
And when are they permitted to leave them (absent emergency) ?

What differences (if any) are there between traffic over sea and over land ?


texts: Where can I get test samples for Assistant Air Traffic Controller Officer exam?

texts:
A few days ago, I applied for the position of Assistant Air Traffic Controller Officer (AATCO), for CAA in Pakistan. The next step is a written test.

What am I supposed to prepare specifically?

My background is in software engineering. Any help/reference will be appreciated.


texts: Which aircraft/powerplant manufacturers use metric hardware?

texts: The vast majority of airframes and powerplants use U.S. standard/SAE hardware. Which manufacturers of engines and airframes use metric hardware?


texts:
{With reference to this video}

Is there any particular reason that land gear retract half way then 2nd gear retract half way and then proceed to retract completely.

Is it related to center of gravity (cog)?

2nd thing I noticed , Tyre boogie is tilted , is there any reason for it ?whats the mechanism behind it? I believed that aircraft land at particular angle , so that all wheel may contact ground at once .is it correct?


texts: How stable is the "customer" power on a commercial aircraft?

texts:
This question on Travel.SE got me thinking... Just how stable is the power that's available via the outlets in the passenger cabin on a modern, commercial aircraft?

My assumption in my answer that it's probably quite clean was based on these things, but I'm not sure if or how accurate these assumptions are:

Power for avionics needs to be clean to ensure there are no spikes or dips that would cause avionic failures as this could lead to otherwise avoidable emergency declarations.
Since the plane is already providing clean power to the avionics, the power coming out of the transformers to step it down to 110V, 60Hz for the outlets should also be pretty clean.

Are these accurate assumptions, or is the effort to provide nice, super clean power to the cabin outlets too much work/too expensive to bother with getting it any nicer than the sketchy quality stuff the power company provides to your house?


texts: What is the standard date format used in aviation?

texts:
As English is the standard language used in aviation and Zulu/UTC time is used as standard too or at least between pilots to calculate flight time and fuel. Is there any standard date format used in the industry like ISO 8601 (YYYY-MM-DD)?
https://en.wikipedia.org/wiki/ISO_8601


texts: Why do DC-4 landing performance charts have different values for the intended and alternate destinations?

texts:
I am studying the landing performances of the old Douglas DC-4 and there are a lot of different landing performance charts available. The pilots can use different flap settings during landing like 45, 35 and 25 degrees. For these different flap settings there are different charts. But there are also different charts for the Intended and Alternate destinations. Can someone explain to me why there are different charts for these?

How can the landing performance be different just based on intended vs. alternate? For example, in the charts for intended destination it says 60% of runway length and for the alternate destination 70% of runway length.


texts: Why is there only circumferential treading on the nose wheel?

texts:
The pilot uses the nose wheel for steering on the ground, still all the tires on the aircraft use the same treading. Why are there no treads perpendicular to the rotation direction?

I know that most of the wheels on an aircraft are there just for the ride since there is no propulsion system acting on the wheels like with a car but the nose wheel has a similar task as the front wheels of lets say a lorry.


texts: What is the meaning of "Docile pitch behavior" in the context of Pugachev's Cobra?

texts:
In another answer on SE Aviation it is mentioned that the ability to perform  Pugachev's Cobra  in a non-thrust-vectored aircraft needs "docile pitch behavior of the airframe up to approx. 110° angle of attack"

Can an F-16 perform Pugachev's Cobra?

What does "docile pitch behavior" mean in this context? Does it mean that when the control surfaces are returned to neutral the aircraft has a natural pitch down moment that returns it to its horizontal position?

If so, does the pilot actually have control over how long he can hold the vertical position in Pugachev's Cobra? What control surface enables him to exercise this authority in the post-stall regime when I'd have assumed the
control surfaces lack such authority?

Or is the holding time of the vertical attitude in Pugachev's Cobra beyond the pilot's control and only related to some sort of "natural period" of this maneuver in that aircraft linked to how long it takes the restoring moment to return the aircraft to its nose down attitude?


texts: Do you need 40 hours in a helicopter to get a PPL add-on if you already have an ASEL PPL?

texts:
FAR 61.109(c) says:

  For a helicopter rating. Except as provided in paragraph (k) of this section, a person who applies for a private pilot certificate with rotorcraft category and helicopter class rating must log at least 40 hours of flight time that includes at least 20 hours of flight training from an authorized instructor and 10 hours of solo flight training in the areas of operation listed in §61.107(b)(3) of this part, and the training must include at least...

The question is, does the 40 hours have to be in a helicopter, or can hours in ASEL meet this requirement? All the training centers seem to be saying it has to be 40 hours in helicopter. Can you theoretically fulfill the other requirements inside the 20 hours training and 10 hours solo in heli and be compliant with 61.109(c) with only 30 hours in heli?

Actually, it's not clear to me if the 20 hours of dual has to be in helicopter.


texts: Are composite materials, which are being widely used in newer aircraft, better at handling bird strikes?

texts:
Do current composite materials handle bird strikes better than their predecessors? Or they are not part of forward-facing components/areas?

For example, the Boeing Dreamliner or the Airbus A350-XWB.


texts: What plane is shown here in the movie Rampage?

texts:
I'm not sure if its a real life airplane, but I feel like I have seen it somewhere:

It looks similiar to the F-117 Nighthawk, pictured below, but it is definitely not this:


texts: How do airlines ensure each passenger has a life jacket before a flight?

texts: It's very easy for a passenger to walk away with a life jacket. What do airlines do in general to ensure that there is a life jacket available for each passenger? Do they check it manually as part of pre-flight check up?


texts: What does the lift coefficient take into consideration for flaps?

texts: Angle of attack increases lift for two reasons, Camber and increased flow deflection, What reason does the lift coefficient use? Both?


texts: Aimed towards lighter piston planes including a powered glider, if a pilot wants to extend a plane's range unconventionally, could flying like a glider by climbing and then gliding down or would flying straight, lower or slower save fuel; even if it means extending flight time?


texts:
There are two vertical bars beyond Vne labelled: @800#-Vg = 150MPH and @840#-Vg = 147MPH. These lines represent Vg at two different weights.

Can you tell me what  Vg is, where it's officially defined, and how it's calculated?


texts: Why do some aircraft have multiple ailerons per wing?

texts:
In a recent flight on an Airbus A380 I noticed that its ailerons are split into three segments which move independently.

What advantages does this design have? Do other aircraft have split ailerons (or other control surfaces)?


texts: What is the average number hours flown annually by a commercial cargo aircraft?

texts: I'm hoping someone has already performed some initial research that might support some preliminary economic models for an aircraft design project.


texts: Birds are usually around airside. Apart from answering it myself, I am looking for community knowledge on this topic.


texts: Why is the sound quality of onboard public address so bad?

texts:
While not a frequent flyer, I did fly common airliners quite a lot, and each time the (very) low sound quality of onboard public adress system has always struck me.

We all know technology makes it possible to have a "HiFi" sound quality almost everywhere, so why don't major manufacturers (Boeing and Airbus) provide better sound quality systems?

While this is of course not mandatory to make an airplane fly, it is related to passenger safety. Better sound quality would allow crew instructions to be better understood during the pre-takeoff briefing and in the event of an emergency.

I have flown with several airlines, and there are already enough other factors that make it difficult to understand what's being said on PA:

On board noise: air conditioning, running engines, neighbors talking, kids crying, ...
Strong or difficult english accent when either the crew or the passenger are not english-native speakers.
Crew speaking really fast.

The airplane companies can't do much on the above items, but they can improve the technical aspects. Of course, I do understand that this would require increasing weight (loudspeakers are heavy...) thus reducing commercial load.

Side question: How do US/EU regulations handle this point? Do they have any specs on sound quality requirements?

Note: I haven't tried recent planes such as A380, so maybe it has been improved.


texts: If pilot use rudder to roll the aircraft at high AOA in the F4 Phantom then one aileron from one wing and one spoiler from other will be deflected?

texts:
I have heard that the F4 Phantom pilots can make barrel rolls at lower speed /higher AOA. They use only rudder deflection and keep the stick column centered (left /right wise)-only pull onto the belly to have the G's- to prevent adverse yaw effects. Does the spoiler on top of the wing move during the maneuver if the aileron stay neutral? The way it works for level rolls is : one side aileron deflected down but the other one is not (there is some slat(spoiler) on the other wing to assist the aileron down deflection. Is there a built in type of assistant like ailerons - rudder interconnection to help maneuvering? Or do the wings remain clean with no deflection of the control surface?

of course it depends upon the situation and the specific fighter. when maneuvering at high angles of attack and high G, I always used solely aft stick and rudder, never any aileron or spoilers input. Sometimes I would use full rudder, all the way to the stops. Other times, not so much.


texts: Are the pitching moment and pitching moment coefficient of an airfoil given w.r.t. the aerodynamic center?

texts:
When the magnitude and sign of the pitching moment and the value of the pitching moment coefficient are communicated, are these values given with respect to the aerodynamic center of the airfoil since the magnitude of the moment of a force is always dependent on the chosen pole O about which the moment is calculated (unless we are discussing pure moments which are independent on the pole O location).
Thanks!


texts: Why does the flare mode of the A321neo engage 50 feet higher than the A321ceo?

texts:
When passing 100 ft RA, the THS is frozen and the normal flight mode changes to flare mode as the aircraft descends to land. The flare mode is essentially a direct stick-to-elevator law without auto trim, with some damping provided by load factor and pitch rate feedback. The flare law provides full elevator authority (source: operating manual).

Compared to 50 ft for the ceo model.


texts: What is the difference between SMOH and SFOH?

texts: When looking at aircraft for purchase online, a lot of acronyms are used.  In particular, the SMOH and SFOH acronyms are thrown around a lot for used aircraft.  What are the differences between these acronyms, and what are their purpose for a potential airplane buyer?


texts: Can a US registered motorglider be flown in Canadian airspace when piloted by a pilot with the appropriate FAA glider license?

texts: Is a PPL-Glider recognized as ICAO approved? Can a US registered motorglider be flown in Canadian airspace (or land at an appropriate Canadian airport) when piloted by a pilot with the appropriate FAA glider license? (NOT an add on to a PPL SEL)


texts: Why do some aircraft approach the runway with a long detour and others with a short one?

texts:
I am currently analyzing flight data. For some flights landing at Frankfurt Airport.

As you can see in the graphic, some of the planes fly out about 100km to then fly again towards the runway. Some only fly out for a short distance. How can you explain that?

I assume that after the cruise phase,  the approach phase depends on factors such as traffic volume at the airport (how many want to land at my time (or in my 10min radius)) and take off?) How is the Operating direction at the airport and what kind planes want to land. Since I was told that the "plane
mix" is also relevant, for example 2x MEDIUM aircraft and 3x large.

Are there rules for such behavior? How does the ATC decide here?


texts: How does the Piper Archer III electrical system work?

texts:
I can't seem to understand how the electrical system works:

What does the ammeter display?

What is said on my POH is that the ammeter displays the alternator output. My question is what output is that? In amps?

Does the battery power the DC bus?

It seems the battery takes AC from the alternator, convert it to direct current, and then feed the entire electrical bus system while still being charged. Is that correct?


texts: Is the differential between the forward and aft CG limits indicative of the overall stability of an airplane?

texts:
Studying up on the Cessna 162 Skycatcher POH to take my checkride in soon and I noticed the differential between the maximum and minimum CG's is a mere 2.5 inches from one to another.

I got curious and looked up the CG limits for the two other planes I train in, the CSA/CZ SportCruiser and the Cessna 172, and saw that the differences between their forward/aft CG limits are 6" and 12", respectively.

In terms of aerodynamic stability, I would indeed rank the Skycatcher (2.5" CGfwd/CGaft differential) as the least stable and the Skyhawk (12") as the most stable. Is there any connection between forward/aft maximum CG differentials and the amount of aerodynamic stability in an aircraft?

Edit:
Still reviewing the responses, having been sent to the encyclopedia several times to study up on new terminology, but I just want to emphasize that the  SportCruiser (6" diff) is dramatically more stable in the air than a Skycatcher (2" diff). Both of these aircraft have the same max gross takeoff weights, 30 foot wingspans and 23 foot lengths. So perhaps the Cessna 172 could be ignored for the purposes of addressing the question.

https://en.wikipedia.org/wiki/CZAW_SportCruiser
https://en.wikipedia.org/wiki/Cessna_162_Skycatcher
https://en.wikipedia.org/wiki/Cessna_172


texts: How to calculate the static pressure in a pitot tube?

texts:
In a pitot-static tube, we have two different pressure, the static pressure $p_s$ and the total pressure $p_0 = p_s + \frac{1}{2}\rho v^2$, which comes from the Beroulli equation for incompressible flows.

Now, lets say we are given an inflow of air from the freestream (assume STP conditions) with a speed of $v_{\infty} = 100$ ft/s. The total pressure would just be $p_0 = p_{\infty} + \frac{1}{2} \rho v_{\infty}^2$, but what I fail to understand is how we would get the static pressure. Would it just be the freestream pressure? Or something else...


texts: How do I determine where the Center Of Gravity needs to be for a Lifting Body?

texts: I'm designing an R/C lifting body which will be boosted to altitude with small rocket motors before gliding back to the launch site. While there's information on how to determine CG for flying wings and conventional aircraft, lifting bodies are wildly different. Does anyone know how I can determine weight distribution for the aircraft to allow stable (well, as stable as a lifting body can be) flight. I'm aware that the spent fuel will cause issues with changing CG, but that's an issue that can be overcome by flight control inputs during the ascent- I'll put the motor in a position that will give the best CG when fuel is expended. I'll be using iNav to hold attitude, so in the climb, the flight controller will compensate for the changing CG. The CG will be the most complicated part of this for now.


texts: What is the difference between "R/C", "Drone", "UAV"?

texts: Are "remote controlled" aircraft and "drones" the same thing? Are they synonyms for "unmanned aerial vehicle"?


texts: Is this plasma-thruster experiment actually measuring thrust?

texts:
This experiment, which is being presented as an initial exploration of the feasibility of using microwave-generated plasmas in a sort of electic jet engine, has been attracting some attention in the general media, for example Ars Technica and Bloomberg News. To put it mildly, I am highly doubtful of the method used to estimate thrust, or even that it is demonstrating any thrust at all, but am I justified in that skepticism?

The experiment involves a vertical quartz-glass tube with an inside diameter of 24 mm. A compressor pumps air into the bottom, and immediately above that, the tube passes through the apparatus to ionize and heat the air, forming a plasma with a temperature up to 1,000 °C. The tube extends upwards beyond that for about another 23 cm, and the upper end is open to the air.

The thrust measuring device is a hollow steel sphere, diameter 75 mm, with a hole in it allowing small steel balls to be dropped into it to change its weight. In use, this sphere is balanced on the end of the quartz tube, and the weight is adjusted until the airflow causes it to wobble (there is a video in the figures section showing this.) The actual measurement of the "jet propulsion force" is the minimum weight of the sphere needed to prevent this wobbling.

On the basis of these measurements, the authors claim to have demonstrated, in this device, a "total propulsion pressure" of up to 24 kN/m², which they say is "comparable to those of a conventional jet engine of an airplane". I am not sure what "total propulsion pressure" is, but my back-of-envelope calculation suggests that they might be thinking of a jet engine's static thrust divided by the nozzle area. Regardless of whether that is so, their figure is simply the weight of the ball divided by the area of the tube, with the corresponding figure for the no-microwave situation subtracted.

Where does one begin to analyze this device? For one thing, at the point where the ball is not yet wobbling, there is presumably no flow (or just a little leakage.) Surely this is a static situation, with little or no relevance to what thrust might be generated? Furthermore, does the weight at which the ball will begin to wobble depend essentially entirely on how much pressure the compressor can reach with its outlet blocked? And pressure given here is only 1/4 atm. -- how much thrust can you hope for, from such a small expansion ratio, even with the best possible nozzle design and a 1,000 °C plasma?


texts: Why circle an airport after takeoff? (SLC particularly)

texts:
I left SLC (Salt Lake City) this morning heading to MCO (Orlando). On previous flights, I remember takeoff similar to other airports. We got in the air, gained altitude, and moved to our heading and left.

This time though, we seemed to circle for a while, gaining altitude. I initially assumed it was to gain enough altitude to clear the surrounding mountain. I ruled out equipment problems because we kept climbing.

Pilots who have experience with SLC, is there a certain runway that needs this altitude gain due to the terrain? Would there be another possible reason this happened?


texts: why do all planes hold position when Air Force 1 is taxiing?

texts: Why does everyone hold in position when Air Force One is just taxiing? This can cause a delay that could cascade to other airports.


texts: Is it illegal to fly a Cessna 172S under day VFR with an inoperative vacuum gauge?

texts:
Let's say my vacuum gauge is not working on my C172S and I want to go day VFR flying.  There is no MEL.  14 CFR 91.213 details procedures for inoperative instruments, and I think the following paragraph applies to my operation, so let me go through these one by one:

  (d) Except for operations conducted in accordance with paragraph (a) or (c) of this section, a person may takeoff an aircraft in operations
  conducted under this part with inoperative instruments and equipment
  without an approved Minimum Equipment List provided -

  ...

  (2) The
  inoperative instruments and equipment are not -

  (i) Part of the VFR-day type certification instruments and equipment
  prescribed in the applicable airworthiness regulations under which the
  aircraft was type certificated; (N/A, vacuum gauge not part of TOMATO FLAMES)

  (ii) Indicated as required on the aircraft's equipment list, or on the
  Kinds of Operations Equipment List for the kind of flight operation
  being conducted; (not sure here*)

  (iii) Required by § 91.205 or any other rule of this part for the
  specific kind of flight operation being conducted; (N/A, not conducting flight at night or IFR)

  (iv) Required to be operational by an airworthiness directive; (N/A, let's assume no applibale ADs)

*This is interesting language: "Indicated as required on the aircraft's equipment list".  AFAIK, to determine if the vacuum gauge fits this description, I should consult the equipment list in the POH, which reads:

Ok, so I now assume any instrument with a number ending in "-R" is "required" for the purposes of complying with the above regulation.  Locating the vacuum gauge in the equipment list, I see it indeed has a suffix "-R", indicating it is a "required item for FAA certification":

Thus I am led to conclude that the vacuum gauge is "indicated as required on the aircraft's equipment list", and hence continuing my flight would be in violation of 14 CFR 91.213.

Is my reading of the regulation and my interpretation of "required item" accurate here?


texts:
On a number of aircraft such as the:

Antonov 225:

A10:

F35:

Use twin tail designs. I understand for military aircraft that the benefit is it allows for a small tail cross section. Reducing the chance of it being damaged in combat.

In the case of the A225 and other similarly designed cargo aircraft it means the rear of the aircraft can be more easily designed as a cargo hatch.

Are there any other reasons why a twin tail design is preferable over a single tail design?


texts: How does the Pratt & Whitney F119 achieve its features?

texts:
The Wikipedia article on the Pratt & Whitney F119 that powers the F-22 says the following:

  The high pressure and low pressure turbines are single stage and counter-rotating, thus shortening the engine and saving weight.
  Turbine: Counter-rotating 1-stage high-pressure, 1-stage low-pressure turbines
  Type: Twin-spool, axial flow augmented turbofan

We also find:

  Thrust augmentation is using additional fuel in a turbofan's cold bypass air only, instead of the combined cold and hot gas flows as in a conventional afterburning engine.— Afterburner

What's the benefit of lighting the bypass air compared to relighting the exhaust? Wouldn't the cooling benefits of the bypass air be lost?
Does that mean that the F-22's "supercruising" could be "augmented"?
How does by counter-rotating the two-spools, the engine becomes shorter and lighter?
How are the turbines counter-rotated?

While the answers are probably buried deep in the Integrated High Performance Turbine Engine Technology program, hopefully some educated guesses can entertain my curiosity.

My only guess for 4. is the use of aggressively curved and converging stators, which would otherwise stall a normal none counter-rotating LP turbine. Or perhaps the lack of a stator in the turbine section, since it's a single LP stage, which would also answer 3.


texts: Do I need 35 hours of ground school for knowledge test for PPL?

texts:
New US student here. I'm starting part 141 flight training soon for my private pilot license, but for now prepping for the knowledge test. I am going with self-study and had a question about endorsement for the written exam.

Is the endorsement I get from the ASA Prepware tool sufficient for taking the knowledge test?

  Complete two practice tests with scores of 80% or better, and request your test sign-off (endorsement) from ASA

I am confused because I've been under the impression that part 141 mandates 35 hours of ground school for taking the knowledge test (also 35 hours of flight time).

https://www.ecfr.gov/cgi-bin/text-idx?SID=2d180e467a3b85b2e34ce695dea3d322&mc=true&node=pt14.3.141&rgn=div5#sp14.3.141.f

  Appendix B to Part 141—Private Pilot Certification Course

  (a) Each approved course must include at least the following ground training on the aeronautical knowledge areas listed in paragraph (b) of this section, appropriate to the aircraft category and class rating:

  (1) 35 hours of training if the course is for an airplane, rotorcraft, or powered-lift category rating.

If not, I might just do Sporty's ground school ($200) and get my endorsement that way.

Thanks


texts: Is In-Seat Rest used regularly where it is legal, and is it restricted by airline SOPs?

texts:
This answer says that a pilot who is not flying (PNF) can make use of a procedure called In-Seat Rest to take a nap during flight.

A comment on the same answer says that this is illegal in the US, but allowed in the EU. Is that true? Where else is it allowed and not allowed?

Is this procedure used regularly in the EU (and other places where it is legal)? Do airline SOPs restrict it?


texts: Why can't the A320's computer-imposed limits be overridden?

texts:
Under the investigation section of US Airways Flight 1549, it is noted that

[The pilot] asserted that insufficient credit was given to the A320's fly-by-wire design, by which the pilot uses a side-stick to make control inputs to the flight control computers.
The computers then impose adjustments and limits of their own to keep the plane stable, which the pilot cannot override even in an emergency. This design allowed the pilots of Flight 1549 to concentrate on engine restart and deciding the course, without the burden of manually adjusting the glidepath to reduce the plane's rate of descent.
Sullenberger said that these computer-imposed limits also prevented him from achieving the optimum landing flare for the ditching, which would have softened the impact.

Although this design aids pilots most of the time, why is there not a 'last resort' option to override the computer-imposed limits? It could have been that in this incident, it was the difference between life and death / a 'hard landing' vs a complete hull loss.


texts: What was the first flight instrument ever used in an airplane?

texts:
It's not magnetic compass, turn coordinator, stopwatch, wind meter, VVI, and airspeed indicator.
I want to know what is the first flight instrument.


texts: Can a helicopter enter Vortex Ring State In Auto Rotation? [see qualifiers]

texts:
If you are in a vertical descent [no wind] with rotor at max RPM Auto, and you abruptly pull full collective, the momentum of the blades will drive air down creating down wash.

Now obviously this is a totally hypothetical question with no real world use, but, presuming a high enough inertia rotor system, in this very specific scenario is it possible to at least enter the incipient phase of VRS? [before the rotor folded and you fell to your death]

Please no answers just saying you go into auto to get out of VRS, I am looking for a very specific yes or no.


texts: How do single GA pilots prevent boredom during long flights?

texts: My question somehow relates to this question asking about how pilots cope with boredom, but now the scenario is not the typical airliner configuaration with two pilots, but with only one. I'm thinking of single pilot operated business jets with flights over, say, 4 hours. What does the single pilot do to prevent boredom and associated problems such as vigilance loss and fatigue? They've got no one to chat with as stated in the first answer to above cited question... of course, they will continue to check and monitor systems, occasionally report and talk to ATC, but there is plenty of scientific evidence (i.e. see this book) a simple monitoring task can easily lead to fatigue - so are there any methods pilots use to prevent boredom and vigilance decrement?


texts: Why were early AFRP A300/A310 rudders prone to delaminating?

texts:
Reading the TSB report about that time an A310's rudder flew the coop, I came across this piece of background information (section 1.12.9.1, History of Earlier Design Aramid Fibre-Reinforced Plastic Rudders):

  In the earlier design of the rudder, GFRP [glass-fibre-reinforced plastic] was used as the bridging layer between honeycomb and CFRP [carbon-fibre-reinforced plastic] only in the reinforced region around the hydraulic actuators. Elsewhere, AFRP [aramid-fibre-reinforced plastic] was used. The AFRP system resulted in poor bond strength of the interior skin. Those rudders experienced large in-service disbonds of the inner skins.  [...]

What made A300/A310 rudders using AFRP so prone to the rudder skin delaminating from the underlying structual framework?


texts: Why is wireless avionics intra-communications (WAIC) not used for air-air or air-ground communication?

texts: Since ITU approved the use of WAIC systems, aircraft designs have evolved and benefited greatly from fuel consumption savings, reduced maintenance (by removing/replacing costly and heavy cable wiring with wireless systems) and improved environmental footprint. However, these wonderful lightweight WAIC systems are restricted to provide bounded inflight services and does not provide air-to-ground or air-to-air communications. What is the reason for this?


texts: Why do gases in the combustion chamber only flow one direction to the gas turbine in a jet engine?

texts:
As far as I know from the working principle of jets engines, compressed air in the combustion chamber (or combustion canister) is mixed with fuel. The ignited mixture expands backwards to turn the turbine rotors and perpetuates the work cycle. Eventually, the left over hot gas creates the thrust.

Although heated gas expands in every direction in space, why does the combustion-gas only expand in one direction, towards the turbine?


texts: What is the commercial passenger aircraft top speed record?

texts:
Aircraft manufacturers claim that commercial passenger aircrafts cruise at the speed of 400-500 knots.
But, is the top speed of a commercial passenger aircraft recorded (while in air)? If so, what is the top speed?


texts: Just a curious thought. Why isn't there any helicopter airline? Airlines that operate large helicopters that can transport 10 or 20 people a short distance?


texts: How do pilots set the exact amount of thrust needed for a reduced power takeoff?

texts:
I know jet-powered airplanes very rarely use 100% available power for takeoff, and most often reduce power to increase engine life. How does a pilot set thrust to an exact level?

The airplanes I'm referring to are common commercial jets such as A320/B737 types.

If they'd set it manually with thrust levers, there are some complications: there are no placards on them. If you try setting revs via the displays, revs and temperatures do not change instantaneously, and looking at the indicators and adjusting the lever would be a dangerous distraction during take-off (imagine: the engines roaring, the brakes are applied and tires are rubbing against the asphalt; or the plane is rolling, and the pilot is looking at the gauges).

On the other hand, if a limit is set via FMS, how does it know when to add more power if it's urgently needed?


texts: Why do police helicopters always fly in circles?

texts: Why do police helicopters always fly in circles while news helicopter hover in one spot? Is it to avoid criminals opening fire at them, or is it because there is a difference between the two types of helicopters?


texts: Are flame holders made of a special material other than that used in combustion chamber?

texts: Are the flame holders made of materials which have higher friction coefficients than the combustion chamber in order to create turbulence?


texts: F-111 emergency landing with no wheel; what is done to reduce risks when loosing a wheel?

texts:
There's an interesting incident described here about an F-111 that lost a wheel during take off.

Couple of questions:

What are the relative risks of an ejection vs a no-wheels belly landing. I mean obviously the costly loss of airframe. But is the risk to life pretty even odds?
In a conventional aircraft (e.g. civillian) ejecting is just not an option so belly landings are the norm. But in an F-111  is a belly landing still safer than a controlled, planned ejection?

The film interviews the pilots & they say something to the effect of

"It's good that someone on the ground noticed. Otherwise we'd have tried landing without even knowing that we didn't have a wheel."

Are there no sensors etc. that'd detect they had lost a wheel? Any other indirect indications based on asymmetric drag, hydraulics etc. that one may expect? In other words, how likely is it that one loses a whole wheel but  does not know.

Are there standard procedures where ATC uses binoculars etc. to check visually whether all seems OK with a landing aircraft (wheels etc.) I know they will check on request, but is there any standard protocol?

Don't military airfields lay down foam for emergency landings? Or is there a downside to foam on the runway?


texts: How much does a refueling stop for an Avro RJ85 cost in Bolivia/Colombia?

texts:
One possible motive for the LaMia disaster is that they were attempting to save money by not refueling. That may or may not be true and this is not the place to debate that.

Reports say they were supposed to refuel in Cobija, Bolivia and after the delay they would have had to refuel in Bogotá. How much would a refueling stop for that airplane have cost in Cobija and/or Bogotá?


texts: Is it viable to put an engine at the rear of the plane like in this photo?

texts: I saw this image on a NASA page talking about hybrids and I was wondering if the back-engine placemente is actually viable and if it is why hasn't been done yet?


texts: Is drag higher when flying in a crosswind?

texts: Is this true that during a flight with a crosswind the drag increases due to the fact that the relative wind blows at a certain angle to the aircraft's nose but not precisely in the opposite direction to its flight path as it would be without a crosswind?


texts: The latest turbofan aircraft feature an exposed exhaust cone, does it come with some benefits?

texts:
Aircraft like Airbus A320neo/A330neo/A350 series have a visible exhaust cone, which is not visible in the older versions of Boeing 747, Airbus A330/A321/A319 etc. Why is this design preferred over the other?
Image: Exhaust Cone not exposed
Image: Exhaust Cone exposed


texts: What if I fail to receive FAA Medical Certificate via mail?

texts:
My AME just called to let me know that my FAA Class 3 medical certificate had been issued and was sent to me via airmail from United States to China. Since April 7th, 2014 when it was dispatched, it has been over 2 months now and I still don't receive the certificate.

I called local postal office and was told I needed to find a 13-digits tracking number (e.g. AB123456789CD, 13 digits, with 2 alphabetic letters at the beginning and end of the string and 9 digits in between) of the mail so they could check for me. The problem is I don't have it and I have no idea where to find it on the https://medxpress.faa.gov website.

Can anyone help me on how I can get this number? What are my options should I fail to get ahold of the certificate?


texts: How strong must wind gusts be to prevent landings and takeoffs?

texts:
I hope this is not as trivial as it sounds. Is there a wind gusts threshold based on which, at a given airport, incoming flights are diverted and outgoing ones are delayed?

I assume that aircraft are designed to handle a specific maximum wind gust, so if there is any such threshold, I expect it to be less than the design threshold. Is this correct?


texts: When using the phonetic alphabet, for airways, should we say Uniform or Upper?

texts: Listening some RTs, I heard ATCos reporting airways, for example: UL65, UPPER LIMA 65. But the phonetic alphabet says UNIFORM. Why do they say like this, please? Is there any manual in which we can study these differences?


texts: How is vertical speed managed in Airliners?

texts: When an Airplane starts to take off, the Horizontal velocity would generate it the necessary lift, and then Airplane pitches up to further increase the lift. As the Airplane is climbing up, the net vertical force on it should be the difference of lift and its own weight. When there is a resultant force, should not the climb rate be ever increasing? And when the Airplane reaches the desired height, I'm assuming - either the horizontal velocity is decreased or Airplane goes to normal state from Pitch-up position, basically balancing the lift with own weight. At this moment, Airplane has some vertical speed right, So Isn't the Airplane supposed to be climbing up with a constant velocity, even after reaching desired rate, as Objects continue to move in the same velocity when there exists no force on them? How is this managed in Airliners?


texts:
I'd like to rephrase the question:

Often I forward-slip on final right right rudder.  During this time, I use the ailerons to keep the aircraft headed down the center-line; the aircraft's bank varies slightly from left wing down, to right wing down.

At some point during this procedure, I have right rudder in and a slight right bank.  I believe this is a skid; Is this something I should worry about?  I would very much like to avoid skidding at all times, especially on final!

Previous question, for reference:

Assuming there is a crosswind and the pilot executes a crabbed approach, during the flare the pilot is going to have to use the rudders to avoid a side-load.   My understanding is that this will result in an uncoordinated flying condition and is prone to stall-spin.

However, this (the flare) does not seem to be much of an issue among pilots.  What am I missing?  How is this any different than a skid?


texts: How to take into account wind in aerodynamic forces balance?

texts:
I'm trying to make a basic simulation for horizontal drift of a falling object due to wind. I need the force balance so that I can find out the acceleration of the object from the wind.

The object is initially dropped with zero horizontal velocity with the only force acting on the object being forces applied by the wind which is a constant velocity. I would like to use an observer on the ground as a reference frame. The projectile will be dropped directly above an observer and will accelerate in the direction of the wind until reaching steady state (velocity of the wind).

I want measure how far the projectile moves in the horizontal direction while it falls to the ground. I am getting confused on how forces are applied to the object.

The way I originally thought the only force was wind pressure applied over the surface area of the object.

$F_{wind} = \frac{1}{2}\rho v^2 A$

I was unsure however, if there was any help from the drag force. Does the drag force add to the force from wind pressure? Is the wind force just the drag force with a different name?

EDIT: Adding some clarification to the problem setup.


texts: Are agricultural pilots allowed to use a highway as a runway?

texts: I lived not far from a spray pilot who had had a hangar in his yard in the country but right off the highway. Would he need some special endorsement to use the highway as a runway?


texts: Why maneuverability and top speed are still issues in 5th generation air superiority fighter jets

texts:
In a previous question someone asked why do modern fighter jet speeds decrease compared to older fighter jets, and someone hinted that nowadays top speed is not a factor considering modern rockets which will anyway exceed the maximum G forces that a human body can withstand.

Now, in the F-22 vs T-50 comparisons many hint at superior maneuverability and top speeds of the Russian T-50 design.

Shouldn't modern fighter jets be all about BVR (beyond visual range) capabilities and thus speeds and maneuverability be "surpassed".

I imagine modern fighter jets to be basically bricks in the air with a lot of high tech long distance warfare technology.


texts: What are the advantages, disadvantages and current state of affairs for text-based ATC?

texts:
This answer has a rather interesting (and quite lengthy) discussion, on a concept of using text-based rather than voice-based communication between ATC and the cockpit. As it turns out, the FAA has some plans for that already as mentioned by @reirab. Being a simmer rather than a pilot, I've always found text-based ATC quite convenient (it provides a direct reference to your own instructions as well as instructions to others on your frequency), but the discussion in the linked answer showed some pilots opposed to such a system. My question is twofold:

What are the advantages and disadvantages of such a system?
What is the current state of affairs of this concept? Are there specific methods of implementation across various instances - e.g., FAA, EASA, ICAO or other regulatory bodies - and do aircraft (systems) manufacturers anticipate such systems, or would perhaps a software update suffice on modern aircraft?

Edit: Perhaps it's better to concentrate mainly on IFR traffic, since their procedures are more formal (spacing, landing sequence etc. are decided by ATC) and things like voice call-outs (e.g., the nice voice that calls you a retard in an Airbus also calls for a go-around) are available at no extra cost.


texts: How many commercial jetliners are equipped with ADS–B?

texts:
The Wikipedia page for Automatic Dependent Surveillance – Broadcast (ADS–B) explains that the aircraft surveillance technology is being phased-in around the world currently, with some due dates in 2017 and 2020 and so on. I see organizations like FlightAware.com are deploying their own ADS-B receivers and are crowd-sourcing data from homemade receivers as well. That leads me to wonder…

How many commercial airliners are currently equipped?

Any reports or estimates by airline or by country/region?

Also: Are private jets being equipped? Are small aircraft being equipped?


texts: Maximum Flaps extended speed Vfe for full or partial flaps?

texts: I fly Piper Archer/Warriors and the POH states "Maximum Flaps Extended Speed (VFE) – Do not exceed this speed with the flaps extended."  I try not to but I occasionally may exceed Vfe with one notch of flaps during a descent.  Could there be structural damage to the flaps in time or do aircraft designers factor in such potential pilot errors?


texts: Why will windshear inop illuminate after landing in an MD-83?

texts: Why will windshear inop illuminate on the annunciator panel after landing or before starting taxi in a McDonnell Douglas MD-83?


texts: Can a company return an aircraft in leasing?

texts:
regarding A380 I see that Singapore Airline and AirFrance return 2 and 5 respectively to their lessors, so I would like to know, how the give back operation works? Are there any penalty to pay?

I was wondering if Emirates too can give back its A380.

Thanks in advance


texts: Is GLS (GBAS landing system) an RNAV approach?

texts:
PBN which is contrast to conventional navigation consists of RNAV and RNP. And I know that general RNAV approach of IAP has up to 4 minima such as LPV, LNAV, LNAV/VNAV, and LP.

And I know that GLS approach is precision approach that use GBAS as well as GPS, but GLS approach procedure chart is separated with RNAV approach chart. I guess that GLS approach is RNAV approach because it use GPS system not conventional aids. Is it correct? is there any official document?


texts:
I noticed several tanks at BWI that store waste deicer fluid. They're in the foreground of the picture; the tanks in the background store Jet A.

What do airports like BWI do with deicer fluid after they collect it? This question is similar but it only partially answers my question. Is the fluid treated the same as household wastewater?


texts: Need more volume with my aviation headset (David Clark OneX). I wear hearing aids

texts: Does anyone know of a way to get more volume out of my David ClarK ANR aviation headset.  I wear hearing aids and often fly in older airplanes with older radios that are scratch/weak/etc.  I select full volume but still have trouble hearing the communications.  Is there any inline booster or something like that?  Thanks....larry


texts: Why do planes generally curve north and not south?

texts: I know that the shortest distance on a sphere is a curve and not a straight line, so that's why planes curve when they fly. But why is that planes curve north and not south? For example, when if I hop on a plane from New York City to London, it'll go northward and fly over Greenland. Could the plane have traveled in the same time but using a route that curves south?


texts: Why/How does a "Powerflow" exhaust increase horsepower?

texts: I've seen airplanes (typically Cessna 172s) with a "Powerflow" exhaust system and then claim to get several more horsepower, resulting in faster cruise speeds.  How does a Powerflow exhaust work, and why does it increase horsepower?


texts:
The KELP (El Paso) Obstacle Departure Procedure (ODP) says:

Rwy 4, 8R: climbing right turn heading 120° and ELP R-150 to 9000, then proceed on course.
Rwy 22, 26L: climbing left turn heading 120° and ELP R-150 to 9000, then proceed on course.

Do I fly from the VOR or to the VOR on ELP R-150?
From: would actually mean I use 150 and fly south east
To:   would actually mean I use 330 and fly north west
Do you have a reference for the answer?


texts: What is the best way to remove stuck screws from Cessna wing tank cover?

texts:
We need to replace the fuel tanks on a Cessna 150 and the screws holding the wing cover won't come out. They are just frozen in place. I think that the paint also may be working against us: Getting the paint out of the screw heads has been difficult. So far no screw heads have been rounded off.

Have any of you had this problem before?
Also, how is the female part under the skin made? Is it like a j-clip nut that can be replaced, or is the nut part a pressed into the frame?


texts: At what point of the design process the manufactures build their first prototype?

texts: I would like to know when the aircraft manufactures decide to put in practice their designs building the first scaled prototype (or maybe the actual size). Does the design have to accomplish a list of basic parameters or something like that?


texts: How to detect landing and takeoff using the value of GND field in ADS-B messages?

texts:
How to understand that an aircraft is landing or taking off by analyzing MSG messages? According to this article we just need read GND field (22). I also heard that during landing the aircraft is sending MSG.2 with field 22 at 1.

I don't understand whether the aircraft is landing or taking off when the field is 1. It seems it just means the aircraft is on the ground, but there is no information about it's exact state.

How to actually detect that an aircraft is landing or taking off?


texts: Why is the XB-70's Top speed only about 60mph higher than its cruise speed?

texts:
The maximum and cruise speeds listed for North American XB-70 Valkyrie are:

  Maximum speed: Mach 3.1 (2,056 mph, 3,309 km/h)
  Cruise speed: Mach 3.0 (2,000 mph, 3,200 km/h)

Why is there such a small difference?


texts: What does it mean "the airport has the code A 129" (Nida airport, Europe)?

texts:
It has been announced that Nida airport (Lithuania) officially opens again and obtains the code "A 129" (here). The source does not say that kind of code it is and what does it mean. Would it be possible to clarify? Is it a place designation, or the airport category?

Nida airport has been closed for many years. It is not very tiny, passenger planes used to land there many years ago. Recently it has been reopened for very small planes while probably something bigger would be able to land there as well. Basically this rather long runway has the status of untowered airstrip.

Nida airport has ICAO code EYND and no IATA code.


texts: Would putting several small propellers on a wing be efficient?

texts:
I saw this video that NASA posted, which presents the idea of putting several small propellers on a wing:

They claim that by doing this you can force air to blow over the wing more quickly. This would make the wings act as if the aircraft was flying faster than it really was, resulting in shorter takeoffs and more control on landings.

However while watching the video I kept thinking, wouldn't the turbulence and slipstreams caused by the propellers actually make the wings perform worse? Or at least neutralize the proposed added lift and control?

Having no fresh airflow over the wings seems like a problem. Have any aircraft ever tried this concept before with successful results?


texts: How are businesses able to use experimental aircraft?

texts:
I saw businesses like this using military jets to sell rides to civilians. Since warbirds are considered experimental aircraft, does the FAA issue special certs to fly them commercially?

According to 14 CFR § 91.319,

  (a) No person may operate an aircraft that has an experimental certificate

    (1) For other than the purpose for which the certificate was issued; or

    (2) Carrying persons or property for compensation or hire.


texts: Does paragliding count towards total time?

texts: Does Paragliding count towards flight hours for "Total Time" in either commercial license 250 or the ATP 1500? If not, what are the cheapest ways to acrue raw "total time" hours? Can one do powered parachutes?


texts: Do I need a trim tab system on my twin tail?

texts: I plan on building a single engine H-tail aircraft with retractable landing gear, removable wings for transportation, and either split flaps or plain. My only problem is, do I need a trim tab system to handle the workload, or should the air from the prop not interfere with the lift and cause problems with aileron, elevator, and rudder control, increasing the muscle the pilot must use to handle the aircraft?


texts: Why are there two red lines on the G-meter in the MiG-29?

texts: Why are there two red lines on the G-meter on the MiG-29 aircraft? One at 7.5G, another one is at 9G. Also on the AOA scale the red line is at only 15 degrees. That is max AOA. It looks very low to me. Or the max G must not have more than the 15AOA? Now it's about the 7.5 G at 15AOA or the 9G at only 15AOA?


texts: Do designers use the same RAM (Radar Absorbing Material) coating across the length and breadth of a fighter aircraft?

texts:
I was looking at this image:

Image from Wikipedia

and couldn't help notice that the RAM coating looks different on the vertical/horizontal stabilizers and wings compared to the fuselage.

Given the fact that there are different types of RAM, such as iron ball paint absorber, foam absorber, etc... Are different types of RAMs being used in order to achieve stealth?


texts:
Apparently airline jet engines lose ~80% of their thrust within 1 second after fuel is cut. However this seems to conflict with long throttle-down times noted in another question.

This lead to a couple of questsions:

How long do jet engines really need to throttle down?
How do they react to fuel-cut or moving the throttle to idle (see first question)
Why the difference between the two answers?
If an engine is throttling down quickly, does the rotation speed of the engine really drop by 80% within 1 second? How does it slow down so quickly, is there so much friction?

I'm mostly interested in commercial passenger transport airline engines, not GA, military, ...


texts: What happens to Vyse and Vxse above the OEI ceiling?

texts:
An EASA ATPL question/answer insists, counterintuitively, that a twin which loses an engine and must drift down will find its least rate of sink at Vxse. I've been trying to understand this, but haven't come up with an answer yet. Do Vy and Vx even exist as concepts when above the ceiling? Does "best rate of climb" become instead "least rate of descent"? Does "greatest distance between the power-required and power-available curves" become "least distance" between same? Would the speeds of Vx and Vy (with or without SE) change when going from below ceiling to above while at the same altitude and mass?
One way to determine Vx and Vy is to look at a ROC vs Speed chart, where ROC will be an inverted parabola. The peak of the parabola is Vy, the tangent of it to the origin is Vx. If the whole curve is shifted below the x-axis, however, the tangent will fall on the far side of the Vy peak. So I would expect Vx > Vy when above the ceiling. But that still doesn't help understand why EASA would say least sink is at Vxse.


texts: Is Ducted fan or Propeller better to maximize forward speed of RC aircraft with a given power?

texts:
I'm designing an RC aircraft of which the final goal is a crazy top speed. I'll be 3D printing and sanding / finishing the air frame surfaces to reduce drag. In order to achieve maximum top speed, should I use open 5 inch diameter 3 blade props (the ones used in racing drones) with a large pitch and beefy motor, or two (60-80mm) ducted fan (EDF) units? Power draw is not a limiting factor here. Also, should I go for a larger EDF than 80mm? (wingspan is about 70 - 80 cm, total mass of about 700-1000g) . I'm aware that EDFs induce a greater delta V on the air they move, but does this actually mean I can expect a larger top speed?
[edit:] I could also go for a single 100mm unit.


texts: How does maintenance differ for military fighters/bombers vs. commercial airliners?

texts:
And why do military fighters/bomber require so many maintenance hours compared to commercial airlines, which seems like just kicking the tires? What do they actually do?

How does maintenance differ for fighters vs. bombers?

As many of the comments and answers have illuminated, "different missions drive different design priorities." Examples of differences in specific maintenance activities would be greatly appreciated.


texts: Why did the flight Osaka -> Frankfurt circle above the airport after taking off from Osaka International?

texts:
When departing form Osaka International (KIX) the Osaka city passed below twice, the second time much lower. Looks like our 747-400 was circling up in spiral before heading a long way over Russia to Europe.

I understand the reason of flying in circles before landing (holding pattern, waiting in a queue for landing). But why circle over the airport of departure? I think it could be more economical and faster to pick the altitude while heading in a needed direction. Is there also a queue to leave the airport? Why not to wait on the ground then?

If was the flight LH741 (Osaka - Frankfurt), departing 24.10.2017, 10:00 from Terminal 1.


texts: Does a Mexican citizen studying in the US with an FAA license need a visa when landing at airports in Canada?

texts:
I'm from Mexico but worked in San Francisco for 4 years under a TN Visa. During that time I learned how to fly and obtained a PPL and then an IFR rating.

I'm now living in Boston getting a Masters Degree under an F1 Visa. I'm interested in flying into Canada. Canada requires visas for Mexican citizens, but a friend claims that there's an exception for pilots. I only want to check out Montreal, so I would be in Canada for 48-72 hours max.

What's a good resource to see visa requirements for pilots from different countries flying into countries other than their own?

Thanks!