texts: If no low-speed compromises were made, what would an ideal Mach-3 wing look like?

texts:
Things like the Concorde and Tu-144 and many other supersonic craft need a wing that has good high-speed and good low-speed performance. After all, it needs to be able to take-off and land. Good low-speed performance is achieved with things like flaps, slats, and the wing shape itself.

But let's just say, hypothetically, you don't need good low-speed performance at all. So no such compromises in the wing shape. What would an ideal Mach-3 wing look like?

The goal is to have a wing with the highest lift-to-drag ratio at Mach 3.

I chose Mach-3 because that seems to be the limit on what jet aircraft have been put into production (MiG-31, SR-71) (which does not count experimental aircraft).

I'm interested in conventional designs, not things like the Blended-Wing-Body. So presumably this ideal aircraft would look similar to the Concorde or Tu-144.

Some things I've noted over the years:

The X-15 had a "wedge" shaped vertical stabilizer with a flat back. You can see it in photos. They said it was because the flat back produces more stability for less drag at high mach. Would a mach-3 wing also have a thick, flat trailing edge?
Ogival Delta seems very popular for large sophisticated supersonic aircraft. Never understood why that is exactly, since the pure delta triangle is easier to manufacture and bear loads easier.
The XB-70 Valkyrie had folding wings to give it anhedral, supposedly to capture the shockwave and thus be a wave-rider, which is more efficient. I've noticed the Concorde also has slightly drooping wings near the tips.

Note: I don't need a complete 3D model of the wing shape. I'm more interested in things like what planeform it has, what anhedral/dihedral if any, etc.


texts: Does the Boeing B787 have safety issues with its battery and windshield?

texts:
AVHerald has reported

An incident of battery overheating. That is after the aircraft has been grounded and parts of the battery system redesigned. AVHerald provides a detailed report on the battery issue.
An incident of a cracked windshield. A cracked windshield typically results in declaring an emergency. AVHerald lists 15 incidents of cracked windshields since 2012. This happens in other aircraft too, but apparently not in the same way. On other aircraft, only the outer of several layers cracks after some time. On the 787 it seems to happen on start or landing, always resulting in a return to the airport. It should be noted, that the 787 windows have fewer layers and larger windows than any other type.

Also Forbes reports, that there have been at least four incidents with the batteries after the FAA mandated four-month grounding, and a physics professor at Canada's Dalhousie University states battery failures are an indication of a problem within the cells.

Incidents with both issues have been reported since 2013, when the 787 was allowed back into service after the FAA mandated four-month grounding.

To me reading this report is disturbing.

Doesn't this mean, that the aircraft is flown with knowingly unsafe battery and windshield?
As a passenger, does one have to be worried about flying in this particular type?


texts: Which kind of aircraft have the lowest operating cost?

texts: As an owner of an aircraft (either for personal or commercial activities), what kind of aircraft is cheapest to operate? The aircraft must be able to carry at least one passenger not for money for at least 150 miles.


texts:
(b) Authorization to perform certain solo flights and cross-country flights. A student pilot must obtain an endorsement from an authorized instructor to make solo flights from the airport where the student pilot normally receives training to another location. A student pilot who receives this endorsement must comply with the requirements of this paragraph.
(1) Solo flights may be made to another airport that is within 25 nautical miles from the airport where the student pilot normally receives training

The student must be endorsed with something along the lines of:

I certify that (First name, MI, Last name) has received the required training of section 61.93(b)(1). I have determined that he/she is proficient to practice solo takeoffs and landings at (airport name). The takeoffs and landings at (airport name) are subject to the following conditions: (List any applicable conditions or limitations.)

Emphasis on the word TO, in (1). I interpret this as "You must be endorsed to fly solo TO another airport for takeoffs and landings." However, my instructor, and it would seem the majority of the instructors at my school interpret it as "You must be endorsed to fly solo AT another airport for takeoffs and landings." The FARs seem to imply my interpretation, and the recommended endorsement seems to imply the opposite (in fact the endorsement doesn't even mention the 25nm part except in title).
The situation it is used in most commonly is the towered-field TO/LDG practice. There is a towered field about 10 miles north of our airport where we all go to practice. However, the instructor is required to fly dual up there, solo the student, and fly dual back. Is this endorsement required in that case?


texts: Do airliners perform a dive maneuver to reduce altitude

texts: DO airliners, jumbos included, like the Airbus A380 and Boeing 747 routinely perform dive (nose down) maneuvers to descend or do they rather reduce speed and descend with the nose up? If not, why not?


texts: What do the white dumb-bell signals indicate?

texts:
From ICAO Annex 2:

  4.2.3.1 A horizontal white dumb-bell (Figure A1-4) when displayed in a signal area indicates that aircraft are required to land, take off and taxi on runways and taxiways only.

  4.2.3.2 The same horizontal white dumb-bell as in 4.2.3.1 but with a black bar placed perpendicular to the shaft across each circular portion of the dumb-bell (Figure A1-5) when displayed in a signal area indicates that aircraft are required to land and take off on runways only, but other manoeuvres need not be confined to runways and taxiways.

The text from Annex 2 is clear. For the first one, aircraft are required to land, take off and taxi on runways and taxiways only. But when is this not the case? Why would you need a signal to specify this - isn't it normally the case that you need to land, take off and taxi on runways and taxiways? Same question for the second one, basically.

Please try to elaborate on the text from Annex 2, and give examples of practical use of these two signals.


texts: Does ground speed represent the horizontal speed measured at sea level?

texts:
Which of the following vectors is refered to as the Ground Speed?

The green one I expect is TAS, the blue one would be Vertical Rate

Note that for simplicity I did not draw them as geodetic curves, but the black one should be shorter than the gray one because of the earth's curvature.

Does the Ground Speed represent the horizontal speed relative to surface at the sea level?

Ex: Helicopter climbing verticaly will have GS=0?

Does the Earth's curvature affect the GS? As the length of the gray vector will be longer the higher the altitude is. Does that mean a plane flying at 1km will have higher GS than a plane flying the same total speed at 10km?

edit:

I'm simulating aircraft movement along a straight trajectory by constant speed. To simplify, the input is start coordinates & altitude and finish coords & alt.

That means the plane can ascend or descent during simulation. I know the total distance between A & B and distance at sea level. So first thing I tought of was:

GS = distanceAtSL / (totalDistance / speed)

In relation to image:

I know the length of Green line and I can calculate how long it will take the plane to reach the end. The time to finish is constant for each line & I know the length of the black line so using formula speed = distance / time I should be able to get the "Ground Speed".

Correct me if I'm wrong.


texts: How did the Boeing 777X's main landing gear lift before the nose on its first takeoff?

texts:
Source: Boeing 777X Takeoff for its First Flight

Is this from a low payload and the configuration of flaps? Or perhaps a pilot pushing the yoke forward while the plane wants to lift?


texts: How does the environment influence the aircraft engine demanded thrust?

texts:
When engineers design the power management of the FADEC, how do they set the required thrust when the pilot pushes the throttle to the TO/cruise/idle position?
I have read some papers, and I found that the demanded thrust is related to the inlet environment, but I don't know how to calculate the influence of the environment, and how to correct the thrust.


texts: What special training is required to fly in the Washington DC area?

texts: I remember hearing that special training was required to fly into the Washington DC area and that it didn't really apply to me (maybe it was VFR only?).  What is the requirement and what must you do when flying in the area?


texts: Is it possible to build a jet engine that utilises all excess heat?

texts: Is it possible to build a jet engine that utilises excess heat for thrust or does not produce any excess heat hence no need for cooling which is wasted energy


texts: How is differential braking different from regular braking? How do you accomplish differential braking and why would you need to use it?


texts: Is it a violation to list an alternate airport based on an approach your aircraft is not equipped to execute?

texts:
A pilot has planned a flight to another airport, and the weather indications at the destination require an alternate airport to be included in the flight plan.  An ILS and a VOR approach exist at the selected alternate airport with standard alternate minimums. The airplane to be flown is not equipped with an ILS glide slope indicator, but it has a VOR.

If the weather at the alternate airport at the estimated time of arrival to that  alternate airport is indicated to be a 700 foot ceiling and 3 miles of visibility is this pilot in the above hypothetical situation violating a regulation by filing that alternate airport?

Another way to word this question is, does the approach that the selection of the alternate airport is based on actually have to be an approach the aircraft is equipped to execute?

Based on the regulation wording in §91.169 this is unclear.  Do any relevant letters of interpretation exist?  Otherwise, can you please provide some written evidence to support an answer on this point?

I have emphasized some of the wording pertaining to how this ties in with a flight plan below in the related FAA regulation.  Nowhere in this wording does it say anything about the aircraft having to be able to actually execute any of the approaches mentioned, only that they're "published for that airport".

I am asking this because it seems contrary to common sense ADM, yet it does not appear to be prohibited.

§91.169(c) IFR flight plan: Information required.

  (c) IFR alternate airport weather minima. Unless otherwise authorized
  by the Administrator, no person may include an alternate airport in an
  IFR flight plan unless appropriate weather reports or weather
  forecasts, or a combination of them, indicate that, at the estimated
  time of arrival at the alternate airport, the ceiling and visibility
  at that airport will be at or above the following weather minima:

  (1) If an instrument approach procedure has been published in part 97
  of this chapter, or a special instrument approach procedure has been
  issued by the Administrator to the operator, for that airport, the
  following minima:

  (i) For aircraft other than helicopters: The alternate airport minima
  specified in that procedure, or if none are specified the following
  standard approach minima:

  (A) For a precision approach procedure. Ceiling 600 feet and
  visibility 2 statute miles.

  (B) For a nonprecision approach procedure. Ceiling 800 feet and
  visibility 2 statute miles.


texts:
How do you control yaw in aircraft with a stick control?

It seems like forward and back are used for pitch, and left/right are for roll, so where is the yaw?


texts: Which aircraft is depicted on 1941 U.S. Post Office airmail stamps?

texts:
Between June 25, 1941 and October 29, 1941 a tri-tailed “Twin Motored Transport Plane” was featured on U.S. airmail stamps in 6-, 8-, 10-, 15-, 20- and 50-cent dominations.

Source

Was the aircraft featured on those stamps an actual aircraft, or was it a Postal Service graphic artist’s conceptualization of one?


texts: Is someone holding an EASA PPL (A) allowed to operate a "November" registered aircraft in Europe?

texts: Is someone who holds a current EASA PPL(A) allowed to operate an FAA "November" registered aircraft in Europe? Of course I'm talking about a type of aircraft and of operation he or she would be allowed to conduct with an, for example, German-registered aircraft.


texts: How reliable are Lycoming and Continental general aviation piston engines?

texts: Statistically speaking, how reliable are Lycoming and Continental general aviation piston engines? What I'd really like to either find or build is a table showing the probability of experiencing engine failure on a properly-maintained piston engine for most of the common models of engine. Is the data out there?


texts:
The answer to another question mentions the rather unusual pivot wing. From an aerodynamical standpoint, what are the benefits of an oblique wing compared to a delta, a trapezoid or a forward swept wing?

Are there any other differences?

Note that I am asking about the oblique wing when it is oblique. The advantages of variable-sweep aircraft have already been discussed at length.


texts: Where can I download the coordinates of navigation fixes/intersections?

texts:
Is there an exportable public database that I may get a copy of all navigational fixes and their corresponding GPS coordinates (latitude, longitude)?
p.s. Only US airspace navigation fix information is needed.


texts: On the EFIS of Airbus you can see 1FD2 on the autopilot section of the FMA. what does it mean?


texts: In this video when the aircraft is turning left(2:25) the spoilers on the wing move. What causes them to move?


texts: Why are the positions of an aircraft's angle-of-attack vanes dependent on airspeed?

texts:
According to this answer to an earlier question of mine, the positions of the angle-of-attack sensor vanes on the A330/A340 are dependent not only on AoA, but also on airspeed (and, according to @ymb1's comment, this is true for all aircraft, not just the A330/A340):

1. AoA vanes are speed sensitive
An AoA vane is in essence a weather vane, but due to various aerodynamic interactions it's not perfect. From flight testing they would have worked out how speed affects the position, and based on that the sensed position is corrected by speed input.

This doesn't make sense - the airflow over the wing is qualitatively the same for a given angle of attack, no matter what the airspeed (as long as you stay below the first critical mach number, at which point you get shockwave formation and all sorts of other goodness), so how can the airspeed affect the readings from the AoA sensors?  Shouldn't the airspeed merely affect how long it takes for them to weathervane in the direction of the local airflow?


texts: How close does a plane have to come to the ground before triggering the ground collision alert?

texts:
The recent AF953 near-miss incident as reported by the BBC describes the ground collision alert warning triggering, preventing a CFIT by the plane.

  An initial incident report published by BEA said an automated warning,
  saying "Pull up", was activated. The plane then ascended quickly from
  9,000ft (2,743m) to 13,000ft (3,962m) to avoid crashing.

  BEA did not say how close the plane came to Mount Cameroon.

How close does a plane have to come within the ground (as measured by the radar) before the warning triggers? Does this number vary significantly between aircraft models, or is there some legislated fixed value for the distance?


texts: Why this inertial regulator of dragonfly wing pitch reduces self-excited coupled flapping and feathering vibrations and improves gliding flight speed

texts:
The pterostigma of insect wings an inertial regulator of wing pitch is linked in this answer to Why do dragonflies have these special little spots on their wings? (open access copy here)
The Summary of the paper includes the following points. I've highlighted some in bold.
Question: Is it possible to explain in simpler terms what "Inertial regulator of dragonfly wing pitch reduces self-excited coupled flapping and feathering vibrations and improves gliding flight speed" means, and why these small weights do it?

The pterostigma of insect wings usually is a pigmented spot close to the leading edge far out on the wing, having a greater mass than an equally large wing piece in adjacent wing regions.

In several dragonfly (Odonata) species the position of the spanwise torsion axis of the wings, the mass distribution of the wings, and the position of the chordwise centre of mass in chordwise wing strips were determined.

In the dragonflies investigated, the torsion axis of the wing lies ahead of the chordwise centre of mass of the wing except at the pterostigma (Fig. 1).

A wing having its mass axis behind its torsion axis is very susceptible to self-excited coupled flapping and feathering vibrations, making gliding flight above a critical speed impossible. Due to unfavourable, inertial, wing pitching tendencies, a still lower speed limit is set to active flight.

Due to its mass contribution and favourable location, the pterostigma tends to raise these speed limits by causing favourable, inertial, pitching moments during the acceleration phases of wing flapping.

The favourable pitching moment of the pterostigma is proportional to the distance from the wing base to the pterostigma, and to the distance of the pterostigma ahead of the wing's spanwise torsion axis. The pterostigma usually has an optimal position at the leading edge of the wing near the wing tip, just where the wing curves backwards. Further optimization of pterostigma mass localization has been obtained in different ways in various insects, involving both pterostigma position (Fig. 4) and form (Fig. 5a).

The function of the pterostigma of raising the critical gliding speed, at which self-excited vibrations set in, was demonstrated in dragonflies. Although contributing only 0.1 % (one pterostigma) of the total dragonfly weight, it raised the critical speed by 10–25% in one species.

The pterostigma is common among the insect orders Odonata, Neuroptera, Psocoptera, Hemiptera, and Hymenoptera. By passive, inertial, pitch angle control, the pterostigma probably makes the wing beat more efficient in slow and hovering flight of small insects, while its raising of the critical flight speeds probably is of more importance to larger insects. The ability of active pitch angle control in many insects does not detract from the value of the pterostigma, since it contributes passively, without power expenditure, towards an efficient wing stroke.

Figures from the linked paper (click for full size):

Images from the linked question, click for full size:


texts: East-West and West-East flight times in relation to earth's rotation

texts: If I were to fly direct from from East to West, and then in the same aircraft do the return trip from West to East, assuming there is no wind on the earth, would both journeys take the same amount of time? This is of interest because logic tells me that the Earth's rotation should make the return trip longer.


texts: Flight time between Taipei - Vienna vs Vienna - Taipei

texts:
I recently took a flight between Vienna (Austria) - Taipei (Taiwan) and then back Taipei - Vienna.

The interesting thing that I don't understand is why it takes longer to fly TPE - VIE than VIE - TPE?

Vienna - Taipei - 11h40mins:
Vienna-Taipei

Taipei - Vienna - 13h 40mins (two hours longer):
Taipei-Vienna


texts: Why can't most jets safely use reverse thrust while airborne?

texts:
According to Wikipedia:

  Some aircraft are able to safely use reverse thrust in flight, though the majority of these are propeller-driven. Many commercial aircraft cannot use reverse thrust in flight

What are the repercussions to using reverse thrust while airborne?


texts: What does a dollar sign mean in a METAR?

texts:
Look at this METAR:

KLOU 151553Z 21005KT 10SM CLR 13/M01 A3044 RMK AO2 SLP309 T01281011 $

What does the dollar sign mean?


texts: Can there be more than one airway with the same name in the world?

texts:
I was working on a programmed simulation of an FMC. I was wondering, regarding airways, if there can be more than one airway with the same name in the world.

i.e can there be more than one airway named UL602?


texts: Is there a limit to the possible altitude for electric jets?

texts:
So I was thinking about Elon Musk's supersonic electric jet idea. Assuming we have sufficiently energy-dense batteries, where would the limits be in terms of speed and altitude.

His logic seems to be: electric (fan?) propulsion doesn't need oxygen -> can go higher -> less friction -> need less power and thrust to maintain airspeed compared to traditional jet

Question: is there some kind of limit for altitude and TAS? I mean suppose the Concorde would be retrofitted with batteries and electric fans. Instead of mach 2 cruising at 18300 meters, assume it would climb to 30km, or even 40km. Air density at 18.3km is 0.115 kg / m^3, at 30km it's 0.018 kg / m^3 and at 40km it is 0.0039 kg / m^3.

So 0.0039 / 0.115  = 3.4%. Meaning the resistance at 40km would only be 3.4% compared to 18.3km. Would that mean the power or thrust requirement to maintain mach 2 would only be 3.4%? Or is induced drag becoming significant at that point? Or maybe it would even stall at mach 2 if flying 40km high?

I mean somehow there must be limits, otherwise we could just fly higher and higher and fly with 0 thrust and still maintain mach 2 (not talking about space flight here)?


texts: What are runway Aiming Point markers used for?

texts:
I'm interested in knowing what aiming points on runways are used for:

Why do some runways have aim points and some do not?
We say that pilots must use the maximum length of the runway. Therefore, why don't we touch down on or near the threshold lines as our aiming point?


texts: Is there currently a measurable shortage of pilots?

texts:
Is there a clearly identifiable and measurable pilot shortage right now? If so, is it a shortage of pilots or of captains, i.e. more experienced pilots? Are airlines changing any personnel rules - like time to go from first officer to captain - that would imply there is a pilot shortage?

If any shortage is for captains couldn't airlines 'upgrade' first officers to fill the places? But presumably that would create a shortage of FOs in turn.


texts: Would it be possible to economically repair 9V-SWB?

texts:
Damage suffered by the right wing of 9V-SWB, a Boeing B777-300.

The complete incident details could be found here.

My question is, would it be possible to repair this aircraft economically, so that it could be reused in future and the repairing costs get recovered from future options?


texts: Why would an F16 battery make a buzzing sound?

texts:
According to this YouTube Video I heard the mechanism that moved the canopy, and then I heard a small buzzing sound. The video description says that it is spooling something, but I don't know what exactly.

Also, I am completely blind, so I have nothing to look at and only rely on sounds to know what is happening.


texts: Why do jet engine fan blades have a twisted shape?

texts: is this a good answer. the blades rotate, the tip moves faster than the hub. So to make the blades efficient, the blades are usually twisted. The angle of attack of the blades at the tip is lower than at the hub because it is moving at a higher velocity than the hub. the amount of thrust generated is higher near the tips than at the root. Engineers want the thrust to be equivalent on every part of the blade.


texts: What is the effect of altitude on true airspeed?

texts:
I know that wind is taken into account when we compute the TAS(true airspeed) and GS(ground speed). However what is the relationship between the TAS and altitude?

For example: What is the true airspeed on the level flight if the headwind is 20 mph and ground speed is 100 mph at 30,000 feet altitude?


texts:
Where did the term apron come from?

Follow up question as suggested by @Pyritie.


texts:
Three letter combinations gives $26^3=17576$ possible codes. Some airports have multiple codes (ARN = STO, for example).

I’m just going to guess that there are more than 17576 airports in the world. Are we reusing these codes?


texts: What is the ground clearance area required for certification for a blimp/airship that needs to be tethered?

texts: Does anyone know how much ground space needs to be allocated for keeping a blimp/airship tethered? I assume it is likely a circular area with the diameter being (2 x total length) + safety factor.


texts: Someone's shooting at my plane out of the blue! What do I do?

texts:
Let us assume that you are in cruise flight in normal, civil-accessible airspace (i.e. not any sort of restricted, prohibited, warning, controlled firing, or other specialized airspace area used for firing containment or security reasons) on an IFR flight plan and in contact with the appropriate ATC agency.  Suddenly, without any warning, notice, or provocation, you see tracers whizzing by your plane!  Assuming you are taking appropriate evasive maneuvers, how do you communicate your situation and your responses to ATC in an unambiguous way? What do you squawk?  7500? 7700?  How does this change for air-to-air fire vs ground-to-air fire?

Furthermore, what evasive maneuvers could a civil aircraft reasonably perform in response to a) air-to-air and b) ground-to-air fire?  Or are you better off not trying to evade fire?


texts:
If both have the same dimension, same amount of fan blade, and supplied by the same amount of energy, which one would product bigger thrust and less total drag (the drag on the blade and the "tube" they are in)? What other characteristic would they differ at?
Clarify: duct fan is driven by a shaft, a shaftless propeller is driven at the rim using electromagnetic force like this "http://www.popsci.com/china-new-submarine-engine-revolutionize-underwater-warfare" or normal mechanical force. Don't mind the fact the shaftless propeller is using on a submarine, I am thinking that if it can propell water it could propell air.


texts: What is the minimum thrust needed to takeoff?

texts: In passenger airplane how much thrust is required to takeoff? What factors does it depend on?


texts: How could a twin aisle aircraft (Boeing NMA) ever have a single aisle (A321) economics?

texts:
I understand from this discussion about the Boeing 757 and 767 that drag is directly related to the front area of the airframe, hence flight efficiency of the dual aisle aircraft can only be significantly inferior to the single aisle design.

So how should we consider current Boeing reflection in the design of the so called MOM or NMA that they seek a twin aisle aircraft with single aisle economics? They are reported to aiming at offering "twin-aisle capabilities—range, comfort, capacity, and faster turnaround time—with single-aisle economics". Is it pure marketing rhetoric or are there parameters other than front area in the equation of such an airplane that would make the assertion sound?


texts: Why does the headset man not get on the tractor?

texts:
As far as I can see, the pushback operation of a passenger aircraft is carried out by a similar application at many airports. It's a towbarless tractor and driver who pushes the aircraft together with a headset man connected to the aircraft walking next to the tractor.

It's strange for me to walk for minutes instead of getting on the tractor. The task of the headset man getting on a tractor will make both time efficient and less tiring. And it’ll be more faster than conventional push-out as well. Isn’t it?

(Source: wikimedia.org)


texts: How would you explain Bernoulli to a nine year old?

texts: This is a aviation principles question coming from my nine year old daughter that I need help with. I was explaining to her the principle of flight and the fact that you need airflow under the wing in order to create lift and that this is why an airplane in a steep climb will stall etc. So she said, why not have two large fans that blow air across the wings (we are not talking about the propellers here, but rather an external fan to create air-flow) so there is always un-interrupted airflow!!!! I am not sure exactly how to answer this. The best explanation I could think to give her was just as a sail boat cannot sail simply by placing a big fan on the boat.....but I don't think she was convinced.


texts: What are some of your favorite flying and piloting related lessons or concepts to share with your non-pilot friends?

texts:
My team at work is doing this thing where each person teaches something new every week. I want to teach them about flying (I'm a private pilot). I'm curious what you think are topics that people find interesting.
I want to skip explaining the physics/aerodynamics but instead focus on some lessons or concepts that can be transferred to other things in life.
For e.g

how everything is designed with safety / redundancy in mind,
single pilot resource management
checklists

What are some other cool ideas?


texts: Is there a fuel injector cleaner additive available?

texts:
I have not seen any additives (such as those used in automobiles) to clean and maintain fuel injectors in aviation engines.   Is there a reason for that such as the use of lead in 100LL or something else?   The fuel injectors will eventually constrict or clog as the avgas leaves residual deposits.

Is there some technical reason or is it just that no one has gone through the certification process or at least (like AVBlend or CamGuard) received the "will do no harm" approval from the FAA?

Removing, cleaning, reinstalling fuel injectors is not only expensive but you also risk damaging them and if you have the GAMI injectors you can have quite a bill coming at you.


texts: What forces act on cascade-type thrust reverser blocker doors?

texts: What is the stress or force that loads the cascade-type thrust reverser blocker doors? As we know, blocker doors are closed and block the airflow going through the C duct. The engine is a V2500 with 25000 lbs thrust.


texts: Which maneuvering speeds are included in the TCDS?

texts:
I've been looking at the data found in various type certificate data sheets and found something that is a bit ambiguous. In reading a TCDS (like this one, for example) in the "airspeed limits" section it lists the maneuvering speed. But they don't make it clear whether they are referencing the design maneuvering speed (Va) or the Maximum operating maneuvering speed (Vo).

Can anyone clarify which one they are referencing?


texts: What is the difference between experimental and amateur built aircraft in the US?

texts:
What is the difference between experimental amateur and amateur built aircraft in the US, or are they the same?

If not, is there a difference re specifications, inspections, engines, passengers, etc.?


texts: Slow Flight for CFI/Commercial Pilot - Should the gear be up or down?

texts:
I was practicing teaching how do demonstrate slow flight in a Cessna 172RG as an instructor, and I have always just assumed that you would extend the gear for the maneuver, but when I looked at the Practical Test Standards (PTS), it doesn't specify up or down, just selected landing gear...configurations.

Does this mean that one should be able to demonstrate slow flight both ways, with the gear extended and with the gear retracted?

  XI. Slow Flight, Stalls, and Spins
  ...

  Task A: Maneuvering During Slow Flight (ASEL and ASES)
  ...

  c. Performance of the maneuver with selected landing gear and flap
  configurations in straight-and-level flight and level turns.

Reference: FAA-S-8081-6D


texts: Could anyone (non-military) in the present day "exceed mach 1 over a regulated area"?

texts:
There is a question What would happen if I exceeded mach 1 over a regulated area?

I wonder, could anyone in civil aviation (not military) actually carry out this violation? I know there are privately owned "warbirds", but it looks like the majority of them are really old. The "never exceed" velocity is defined well below Mach 1 for majority of these planes.

Are there any cases known where someone non-military owns an aircraft that could exceed the speed of sound and then land at least mostly in one piece?

Let's limit the scope of the question to USA and Europe.


texts: What would be the designation for 4 parallel runways?

texts: If an airport were to have 4 parallel runways (ex if KSEA added another one), what would the designations be. Would it be 34L, CL, CR, and L? I know in Orlando they are separated by the terminals, and thus quite far apart, and they're numbered 17 and 17 and 18, for example. But if they were right next to each other, would that make a difference? Would the two-number system still be used there?


texts: Where is the generator in a large turbofan of a commercial airliner?

texts:
So, where do you put the electrical generator?

If it's gonna be coaxial, the only place is the rear (it will be burnt) or the front (it will get in the way of intake).

If it's gonna be coupled to a gear, I can't see how to mesh a gear onto the spinning parts, because the bypass air surrounds the entire engine.

Note: I'm interested in large turbofans of large airliners like the A380 or Boeing 787, basically anything with turbofans carrying 200+ passengers.

(P.S., does the generator spin from the LP turbine or the HP one?)


texts: How does an aircraft's weight affect the V-n diagram?

texts:
I have a reasonable understanding of what a V-n diagram shows and what the envelope and the boundaries mean. However, the question I have is how does the weight of the aircraft specifically affect the diagram?

I know that reducing the weight will mean a lower load factor and therefore potentially more manoeuvrability. But is there a mathematical way of showing this? Also, how does the weight relate to lift? Again, lower weight means less lift is needed. But how does that specifically affect the V-n diagram?


texts: Why did the north / south runways close at Daugherty Field (KLGB)?

texts: The north / south runway at KLGB were recently closed.  Does anyone know the reason for the runway closures?


texts:
On this question SentryRaven gave the following list of ATC stations:

Delivery (if available)
Apron/Ground (if available)
Tower
Departure (if available, sometimes handled by Approach)
Enroute ACC/Center (multiple stations along the route)
Arrival/Approach
Director (if available / in use)
Tower
Ground (if available)

I am not familiar with Director. What does this ATC position do and when is it used?


texts: I haven't noticed any sort of plug door, so how do pilots board the B-2?


texts:
What happens to the unused food after a flight? Does it get all destroyed (on-site or off-site) or is there some alternative use (e.g. Charity ) that it gets put to. Does the incoming food truck cart it off with the carts or is it handled by the Janitorial / Clean Up crews.

On shorter sectors can some items be used on the next flight with the carts only being "topped up"?

PS. Obviously, I'm referring to the perishable items with short shelf lives. Not talking about peanuts and other packaged items that last with longer shelf lives.


texts: Low-wing taildraggers pictured on 2021 ASA FAR/AIM cover?

texts:
There are a pair of low-wing taildraggers on the cover of the 2021 FAR/AIM published by ASA. Can anyone identify them?
I tracked down the image source here, but the description does not identify the planes:
https://www.istockphoto.com/photo/motor-aircraft-on-the-ground-gm1131409963-299576828

Zwei farbige Motorflugzeuge Sportflugzeuge stehen am Boden auf dem Rollfeld eines Flugplatzes.
Translated to English:
Two colored motorized aircraft, sport aircraft, are standing on the ground on the tarmac of an airfield
Does anyone know what they are?


texts: How many active large commercial airplanes are there?

texts:
For example, the 747 Wikipedia page says that 1500 747s were produced (that number seems quite low!).

Any indication of how many large, commercial aircraft there are, and what the breakdown between passenger and cargo is?


texts: Why are airports like Roswell and Fresno so popular for flight tests?

texts:
I recently visited Roswell, NM, and was surprised at how many flight tests have been performed there.  Even the fatal Gulfstream flight test crash happened there. My research shows that a lot of flight tests happen at places like San Bernardino, Roswell, Fresno, and  Moses Lake. My research turned up only simplistic explanations for why these airports are so popular like "Boeing chose the San Bernardino facility because of three factors: hangar size, availability and weather." (Source: The Sun News)  Is that really all they consider in determining flight test locations?

I've heard that you can't do flight tests at just any airport, though I haven't been able to find any relevant legal restrictions.  The airport choice doesn't even seem to be just the obvious factors like weather, runway length, and GA availability.  (I also don't care about specialized testing that would require unusual airports like long runways or specific temperatures.) There are a few dozen low-volume long runways in the arid American West and similar regions.  Why are just a few so popular?  Are there any FAA (or EASA) restrictions on doing flight tests at any old airport?


texts: Is it Legal to listen to Air Traffic Control Frequencies in the USA on a computer for entertainment?

texts: like listening to scanners an radio frequencies for entertainment and i make it a game because i use a online flight tracker and try to find that aircraft. Is it legal?


texts:
In a recent question I asked, I was given an answer by Peter Kämpf and he described something about lift being created by a vortex used on delta wings and the Bird of Prey wing.

How exactly does vortex lift form to generate lift and on what other types of wing is it used on?


texts: Callsign includes the term 'with Kilo' ; What does that signify?

texts:
In FS-X I sometimes see with Kilo at the end of a Call-sign. For example the one from last night had

  Mike Sierra Alpha Bravo with Kilo

What does With Kilo mean?


texts: What can a pilot do if an air traffic controller is incapacitated?

texts:
I watched this video:

where a Las Vegas controller is on duty alone and suffers a stroke.

The pilots become quite uncomfortable with the situation and basically everything is stopped.
Someone finally calls the company and gets them to check up on the controller.
Fortunately it was not that busy, and no other emergency emerged.

What else could the pilots have done to remedy the situation?


texts: What can be expected in an airline interview?

texts: So after the long wait, when someone finally gets that phone call for an interview at an airline, what do they need to study?  What kinds of questions will they ask during the interview?  How many interviews do they typically have to go through before a hire decision is made?  In short, how does it work?


texts: Is lashing equipment considered part of a ULD?

texts: How should a load controller state additional lashing equipment on a load sheet in the context of ULDs? Should the additional weight equipment be added to the ULD's contents, or added to the ULD tare weight? Listing the additional equipment as Equipment In Compartment (EIC) does not seem to be a possibility.


texts: I want to be a French fighter pilot. Any advice?

texts:
Hello everyone!

I want to be a French fighter pilot and I would like some advice from retired fighter pilots about how you should do things if you were at the same age as you were when you entered the army but having all the knowledge you have now.

Thanks for reading. If you see anything that can be improve (even the question), let me know! It's the same for questions or/and remarks, let me know!


texts: What sensors are required to fly RNAV 5 airways?

texts:
In the example shown above:

Is an aircraft required to have all 3 sensors listed or just one of them to fly the L512 airway? What ICAO reference confirms the answer?
Does 'critical DME' (bottom row) mean an aircraft is required to have DME/DME? Or can an aircraft equipped with GNSS still fly the L512 even when KAE or KPO is out of service?


texts: Why do airplanes start descending when we initiate a left turn?

texts:
Today I watched a video about the Fly-by-Wire (FBW) system (see below) and at 3:20 there is a left turn initiated in a Cessna 152. Then it is shown that with a left turn (only by ailerons), in aircraft with a mechanical flight control system, it will start a descend (and a slip).
I understand why the aircraft starts flying a slipping turn, but I don't understand why it start descending. Because gyroscopic effect would make the aircraft to pitch up in a left turn.
It is also said that each aircraft with mechanical flight control system, either little Cessna or Boeing 737, will have that tendency. Can somebody explain that descending tendency?
My guess is that the turn is initiated without power increase, so to stay with the same indicated airspeed the aircraft must be pitched down, but I'm not sure of that.


texts: Why do the engines of the PAK FA (Sukhoi T-50) seem not to be not aligned parallel to each other?

texts:
The nozzles of the Sukhoi T-50 seem to be aligned not perfectly parallel. However, it is not very pronounced.

What may be the reasons for aligning the nozzles engines not perfectly parallel.

Edit: in my original post I asked about the nozzles, however, as it was pointed out, this plane used 3D thrust vectoring, so the nozzle arrangement might be this way by chance. However, also the engines seem to be aligned not perfectly parallel. The question has been edited accordingly.

Image source Wikimedia

Edit 2: Here is another picture
Image source, Wikipedia again


texts:
Today, I played with styrofoam gliders with my kids; I made an asymmetric  wing, asymmetric horizontal tail, symmetric vertical tail, and attached these to one stick for the fuselage.  I've had big problems with pitch stability, so I played with adding mass to the nose, hoping to solve the problem.
Every time I throw a glider with my hand, the nose lifts up or falls down (which one depends on where I set the glider's center of gravity), and the glider crashes.  I set the tail to produce downforce, but I can't find the right pitch balance to make the glider fly well.
I know that, for level flight, the CG has to be in the same place as the glider's overall center of lift (both wing lift + tail lift).
Should the horizontal tail have a symmetric or asymmetric profile, and what should the angles of incidence for the wing and tail be?
Maybe the best way is to put the CG at the wing's center of lift (at the 25% chord line) and set the tail to a neutral position (producing no positive or negative lift)?
What is the easiest way to calculate where to place the CG if I don't know how much lift is produced by the wings and tail?


texts: How do pilots decide whether or not to deploy a ram air turbine?

texts:
Since the turbine needs to be deployed from within the aircraft to the outside, it will obviously induce aerodynamic drag (slowing the plane down?).

I mean I remember reading an article where a plane that for whatever reason did not stow it's landing gear and ending it burning significantly more fuel than planned.

So my question is what checklists and other factors to pilots need to account for before they decide to deploy the RAT


texts: Where can I find full wing polar data to validate an aerodynamic code?

texts:
I am looking for polar data of a full wing to validate an aerodynamics code I an working on.
I am looking for the Cl, Cd polars (and Cmy) and the planform and airfoil geometry, I am also looking for the polars computed at various Mach numbers.
I looks through the Internet and read many AIAA papers but I never found all the elements I am looking for in one of them.
I heard about the ONERA M6, DLR-F4 and DPW reference wings but I never found a full study of one of those (with numerical data). If someone can provide me with such data I would be very happy.

To go one step further I am also looking for such kind of data for a straight wing.


texts: What regulatory load cases drive the structural design of aircraft?

texts: What I am looking for here is a sort of a list gathering the manoeuvres and/or load cases imposed by regulation that lead to the sizing of a part of an aircraft. For instance, vertical gust load is often the load case that has to be used to size the structural parameters of the horizontal tail (bending moment). What are the other load cases and manoeuvres that usually size the subparts of a commercial aircraft ?


texts: How does maneuvering affect radar detection of stealth aircraft?

texts: Stealth aircraft like the F-22 and F-35 have very low radar cross sections. These planes have angles of their fuselage set-up in a way to deflect radar signals. As far as I understand another stealth property is that the aircraft itself is relatively flat. When it comes to maneuvering and for example rolling the plane do these features still apply, as the "flat" effect is pretty much gone? So how does maneuvering affect radar detection?


texts: Why force the nose of 737 Max down in the first place?

texts: Can someone here explain a pretty basic question that I have had  ever since this controversy came to light? I don't understand why any aircraft manufacturer, engineer, software developer, would make a device that forces the nose of the plane down. You can't land unless you're in control and landing safely is the only reason to go down that I know of. So I just don't get that as an initial thing, but the second part of that is, given the hazards of pointing the nose down, which are obvious even to me, why would you not design the system so that it's a warning, and allow the pilots who are actually sitting there to decide whether going down is a good idea or not? That just fundamentally, as a threshold issue, makes no sense to me at all. So I'm hoping you could help me understand. Thank you.


texts: Is TBO an airworthiness item or just a recommendation?

texts:
In browsing Trade-a-Plane for my dream (light GA) ride, I often note the TBO (Time Before Overhaul) for an aircraft in relation to its asking price.  Obviously, the more time left before an overhaul is due, the greater the value of the airplane compared to one that is near or beyond its overhaul due date (hours).

I've always assumed this was an airworthiness item, meaning the aircraft was illegal to fly if it was overdue for a major overhaul.  But now I'm not so sure.  I've seen aircraft advertised as having a relatively recent top overhaul while being overdue for a major overhaul and I've seen a couple advertised that were overdue with no recent work done. Is a GA aircraft legal to fly if it's overdue for maintenance, and what are the exact rules for this?


texts: Difference between Mach buffet and shock stall

texts: What is the difference between Mach buffet and shock stall?


texts: Why do older airplanes have the wing curved upward like a 787?

texts:
I was just wondering one day about because the 787 uses a wing flex to reduce wing tip vortex, but back in World War 2 they didn't know about wing tip vortex, so then why would it be curved upwards?

You can see in the middle picture the wing is curved upwards. I see this on a lot of commercial airplanes too like the Boeing 737


texts: D.B Cooper incident - What caused the tail to move after a jump?

texts:
In the Wiki page on "D.B Cooper", the presumed moment he jumped out of the aircraft is described:

  At approximately 8:13 p.m., the aircraft's tail section sustained a sudden upward movement, significant enough to require trimming to bring the plane back to level flight.

This was replicated in a test:

  In an experimental re-creation, Scott piloted the aircraft used in the hijacking in the same flight configuration. FBI agents, pushing a 200-pound (91 kg) sled out of the open airstair, were able to reproduce the upward motion of the tail section described by the flight crew at 8:13 p.m

What was the likely cause of this? My initial thought was it was his body striking the tail, but that isn't mentioned and doesn't seem to be what happened in the test.


texts: How many warning signals are voiced in modern airliners?

texts:
Some warning signal in modern airliners are voiced, like TCAS warning and GPWS warning (PULL UP!).

And how many warning signal are voiced in the modern airliners?

Moreover, where is the sound produced?


texts: If you turned base early, cutting off other traffic, what is the safest way to rejoin downwind?

texts:
Joined the left traffic pattern at a controlled field downwind.  Controller informed me I was number three for landing. Saw traffic on final, turned base, reported to tower "following cessna on final". Controller comes back a minute later and realizes I cut off a plane on final and I was now number two (my mistake here.  I realize now, I think, I should have not maneuvered at all unless I was 100% sure I could see planes 1 and 2 on final). Controller tells me to rejoin the downwind.  At this point, I was still on the base, so I turned right to rejoin the downwind and the plane behind me that was on final passes too close below me while I am executing a turn from base back to the downwind.  Didn't seem safe.  In fact, as soon as the controller told me to rejoin the downwind, that didn't seem safe.  I am not sure what I should have done.  I could have A) had more situation awareness and turned left to get back to the downwind  B) called for a go around (on a base?), moved to the upwind leg (not departure) and rejoined the pattern. C) the controller should have told the plane on final that was behind me to get out of the patter by going around to the upwind leg.

I realize I caused this issue by maneuvering to base following the wrong plane.  Like most aircraft incidents, it is usually a combination of factors. I caused the first, did I cause the second?  Should I have called for a go around. What should the controller have done?

In the future, I can fix my issue. But what do you do if you are cutting off for whatever reason a plane on final, while you are on base. What is the safe way to get out of the situation.  Ideas?  Thanks


texts: What is the history and process of designing new waypoints and airways?

texts:
I am interested in what goes into designing new airways and navigation fixes, especially on international routes. For example, after WWII, there were no established international air service. Now, we have waypoints (defined by coordinates), VORs, high and low altitude airways etc. connecting across continents. So at some point in history, somebody decided to add a new airway and a set of fixes to the charts. But exactly how?

Who decide where and what to put on the chart? Is there a panel with representatives from major airlines? Or, if government authorities are involved, what happens to waypoints above international waters?


texts:
At first I thought it was a plane that had its wings removed for some reason.

Then I thought it might be a lifting body, but I don't think so. Any ideas? This was in Jacksonville, FL; I can provide the coordinates if needed.


texts: Do airliner spoilers really "spoil" lift?

texts:
The two illustrations below show the typical spoiler location and the lift distribution of a wing. For comparison a third picture shows the location of spoilers on a glider.

It appears the airliner spoiler is located so it destroys very little lift but would really only contribute to drag - is this really the primary contribution spoilers have to the aerodynamics of an airliner or is there more happening here?

Typical location and size of airliner spoilers. - source

Typical lift distribution of wing. Red references have been added to show typical airliner spoiler. - source

For comparison, a glider spoiler located at the center of lift - source


texts: When does the use of afterburners save fuel?

texts:
An afterburner uses a lot more fuel for a little more thrust (rule of thumb: 50% more thrust for 5 times the fuel flow with full dry power). Is a flight maneuver possible where using the afterburner will result in less fuel use than flying the same maneuver with dry thrust?

To be precise: I am looking for a situation where the aircraft transits from state A to a desired state B. The transition is possible with both dry and wet thrust. Please describe a pair of A and B where less fuel is used in the transition when the afterburner is lit!


texts: Can I legally taxi a seaplane in a canal or channel?

texts:
I live on a good sized canal in a subdivision in Florida, USA.

Is it legal for me to taxi down the canal about 100 yards?
Is it legal for me to taxi down a large main channel which is part of the Gulf of Mexico to take off?

Also, when meeting a boat, who has right of way: the boat or the seaplane?


texts: Are there any twin engine aircraft without counter-rotating props?

texts: All the twins I have checked have counter-rotating blades, so I was wondering if this was true for all twins of if there are any twins that have both blades turning in the same direction.


texts: Where to start learning how to fly and build flight hours?

texts: High school student here. I really want to be a commercial pilot since I was a kid. I really don’t know where to start learning, either cadet pilot school (funded and organized by the airline), a flying school with a flight instructor, or the Air Force. Any recommendations? Experiences? Advice as to how I can start or what I can do as of now?


texts: What are good study guides/practice tests for the airframe maintenance certificate?

texts: I am approaching my 18 month mark on the job. Wanting to get my A license first. I have done all kinds of airframe work in this time period. Wondering if anyone has suggestions for the names of the good practice tests books for general and airframe. I have the FAA books on all 3 subjects just no study guides or practice tests. Any suggestions?


texts: Could a Dyson fan scale up to be used as a bladeless aircraft engine?

texts:
Dyson has been making bladeless fans for a few years now that accelerate a consistent stream of air without exposed blades.

If this concept were applied to aircraft engines, it could potentially reduce the number of bird strikes, engine complexity/part count, danger for ground crews, etc. That said, it has not been done (or has it?). What are the major roadblocks prohibiting engineers from scaling this technology to large aircraft applications?


texts: Is it common for carriers to have separate certification for analog versus glass cockpits?

texts: Is it common for carriers to have separate certification for Analog cockpits versus Glass (digital) cockpits?


texts: Is it possible for a plane to use cameras and screens instead of a clear windshield?

texts:
I was just wondering: is it possible to have a commercial plane with no cockpit windshield, just external cameras and video screens?

The question come in my mind after reading the nth occurrence of laser in pilot's eyes. Moreover, a structure without windscreen is surely lighter: when there are not passenger, we avoid to put windows! Which are the limits and the opportunities to this solution?

With "ever" I don't mean "in centuries" but in 30/40 years.


texts: Why don't bombers have close-in weapon systems (CIWS)?

texts: Besides the TU-22 radar-controlled rear-cannon, why aren't there close-in weapon systems (CIWS) on planes to defend against incoming missiles? The tech seems to be there.


texts: Why is IGN SYSTEM A FAULT dispatch a NO GO on the A320 for ETOPS?

texts:
In the A320 MEL if Ignition system A is under MEL the aircraft can't be dispatched for ETOPS. Why is it specifically restricted for ETOPS because even while conducting non ETOPS
 if we go into emergency electrical configuration we will still lose ignition system A.


texts: How do passengers board the planes on this airport?

texts:
I found a quite "rare" layout on Munich airport. It has jetbridges but I don't see any terminal. Look:

How do passengers make it to this point of the airport? By underground?


texts: Would it be viable to install a screen in front of jet intakes to prevent them from sucking in birds?

texts: Why isn't there a protective screen with large diameter holes (approx 2') mounted in front of the jet engine intake to protect the turbine blades? This would  keep larger birds and large ground debris from getting sucked in, which can cause serious internal engine damage.


texts: What's the typical cost (and its breakdown) for a long-haul commercial flight?

texts:
I realised that this question is very broad, but I intend it as an example to illustrate the actual costs incurred by a typical long-haul commercial flight.

For the purpose of this question, I would assume the following:

A380 or (modern) B747 in typical 3-class configuration
Full occupancy
12 hours flight time (or more)

Here are the cost position I can think of right now:

Fuel
Aircraft amortisation
In-flight crew salaries
Ground crew salaries (boarding crew, aircraft preparation and cleaning, luggage loading, etc.)
Catering
Various insurances
Airport fees (landing tax, etc.)
Overflight fees
Administrative cost (managing/issuing tickets, etc.)

What am I missing? What would be the absolute (and relative) cost budget for each of these?

Bonus question: in airline operations, is this cost typically handled as "per flight hour" (as in general aviation), "per flight", or in another way?


texts: What are the Ikarus C42 wing loading limits?

texts:
I have been reading about the Ikarus C42 aircraft as a potential personal recreation aircraft.  It compares very favorably with the Cessna 152, most notably in weight, stall speed, and fuel economy.

Does anyone have info on the negative and positive G loading limits for this aircraft? Can it be dis-assembled for transportation and storage? Thanks.


texts: What's the difference between a Sole Means Navigation System and a Primary Means Navigation System?

texts: For bonus points, how you define a supplemental means navigation system?


texts: Can a deployable ILS operate in CAT II or CAT III? As far as I know a deployable ILS can operate only in CAT I.


texts: Why does the B-52 have such a tiny rudder?

texts:
The B-52 (aka Stratofortress, aka Grey Lady, aka BUFF) has a minuscule rudder for an aircraft of its size and wing-mounted engine placement:

Compare to, for instance, the rudder on a 747:

The B-52’s rudder is so small that it can’t be used to decrab the aircraft during a crosswind landing, meaning that it had to be designed to stay crabbed throughout the landing roll, forcing the designers to use a fully-steerable dual-bicycle landing gear layout (plus wingtip outrigger gears that are there solely to keep it from tipping over) instead of the conventional tricycle arrangement.

Why, then, did the B-52’s designers give it such a small rudder?  One could argue that, because it has four engines on each side, rather than one or two or three, it doesn’t need a large rudder, because the thrust differential (and, thus, yawing moment) in the event of an engine failure would be minimal).  However, if you look more closely, that argument doesn’t hold up, because the B-52’s eight engines are mounted in conjoined pods, two engines per pylon, which virtually guarantees that an engine failure will also take out the engine right next to it;1 thus, one would expect that the design case for the B-52’s rudder would be a double engine failure of both engines on one pylon, rather than the improbable case of one engine failing and somehow managing to leave the one next to it completely intact.  So why isn’t the B-52’s rudder bigger?

1: For instance, the danger of cascading engine failures is one of the main reasons why no airliner designed after 1960 has ever used conjoined engine pods.


texts:
What is the necessity of Obstacle Departure Procedure(ODP)?

Standard Instrument Departure(SID) is enough, isn't it?


texts: Why does Thai Lion Air use loads of 737 ERs for 1-2hr routes?

texts:
Thai Lion Air primarily flies short-haul domestic routes and most of the time I find myself on an ER version of a relatively new 737. Isn't ER for extended range? And thus costs a lot more per plane?

Incidentally their sister company Malindo also has what seems to be an unnecessary amount of ERs (I just flew on one this morning from KUL to BKK - a 110min flight - and one the week before from KUL to HKT, again under 2hrs).


texts: Is it possible to do linear interpolation on a manual E6-b?

texts:
Suppose the performance tables for my fictional airplane indicate the following:

    Density             Takeoff
  Altitude (ft)       Distance (ft)
----------------    ----------------
       0                 1,865
      2,000              2,602

Suppose that the density altitude of the day is 1,400 ft and I would like to calculate my takeoff distance.  Obviously I could do it using the linear interpolation equation:

\begin{align}
y &= \frac{(x-x_0)(y_1 - y_0)}{x_1-x_0} + y_0 \\
&= \frac{(1400-0)(2602 - 1865)}{2000-0} + 1865 \\
y &= 2,381 ft
\end{align}

...but that's a lot of numbers.  I suppose some digital E6-b's might have a linear interpolation solver, but is there a clever way to calculate (or estimate) it using a manual E6-b?

Edit:  To be explicit, I could not care less about actual takeoff performance for the purposes of this question.  It's just there so we have a common example to use when discussing the actual question of E6-b manipulation.


texts: What do the various A340 configurations (clean, 1, 1+F, etc.) mean?

texts: Could anyone describe (or direct to usable documentation) me aircraft configurations? What does it mean clean configuration, configuration 1, 1+F, 2, etc... Is there any section in FCOM's describing it in clear way?


texts: Is starting a jet engine without ground support possible?

texts:
We have had more... than... one question about jet aircraft taxiing about the airport without their jet engines running. Those address several issues such as cost vs savings and regulatory approval.

My question assumes that an in-wheel electric motor, tug or even pull-chain based solution has been developed, certified, deemed cost-effective and installed.

Let's say that I am now sitting on the taxi-way and am 5th in line for take off. It's time to fire up those jets so they can warm up and we can get the beast into the air. According to this question about how turbine engines are started, it appears that I'm going to need some sort of ground-based support to get the N2 stage spinning. That question indicates that a couple of early, WWII era, jet engines had a built in motor that could get the turbines spinning fast enough for a start, but it seems to me that any modern commercial air-carrier grade engine will need some sort of external help to fire up. I suppose if there was a tug that had pulled me to this point, it could have the support infrastructure built in to get the turbines spinning, but any sort of self- (or ground-) propelled system would seem to lack that.

Now that we're nowhere near the terminal, how the heck are we going to start the engines?

I realize that this question is somewhat speculative in nature, but I believe it could be answered based on some existing or in-development ability (that I'm not aware of) to start an engine without ground support. It could also be my misunderstanding that ground support is not required to start a modern commercial aircraft engine (GE90, RR Trent series, LEAP etc.)


texts: Where can I find information on dethermalizer aerodynamics?

texts:
A dethermalizer is a device that alters the aerodynamics of an airplane, glider etc, allowing it to descend quickly.

Are there any sources - including equations and derivations - on dethermalizers, as (most often) used on free flight model planes?

Source: Youtube.

The most detailed information I've found so far is NASA's low speed controlled deep stall sailplane tests, which contain many measurements graphs and verbal descriptions, but no math to explain this behavior.

NASA Technical Paper 3022, 1990
NASA Technical Memorandum 86041
NASA Technical Memorandum 85917


texts: What are ARTCC, RCO and FSS and what are differences?

texts:
I am confusing what ARTCC, RCO and FSS. and also what do they do?
Do they control air traffic by communicating with pilots?
Also, do they offer WX information in air born?


texts: Is there a minimum altitude for ejection seats?

texts:
Is there generally a minimum altitude for ejecting in order for the sequence to function reliably (all the way to opening the chute, and slowing down to a survivable descent rate)? I've seen ejector seats test being done on the ground, don't know if there were actually test pilots in those seats though.

I assume all bets are off if you're not wings level (obviously a low-level inverted ejection has a 0% chance of success).


texts: Can a private pilot placard an inoperative instrument?

texts:
For certificated small aircraft that are not required to have a minimum equipment list. If you have an instrument break while on a cross country flight and it is not a legally required instrument for the type of flight. You are on the ground at a distant airfield and would like to return to your home-base mechanic rather than hiring an A&P in the middle of the trip.(or if the airport has no local services)
Can the pilot legally label the instrument as inoperative for the duration of the trip without hiring an A&P to officially "deactivate" and placard the item?


texts: Why don't some spoilers plates fully open in most airliners?

texts:
The following image illustrates my question:

What's behind the manufacturer decision of opening some spoiler plates less or more than the others? I noticed this is quite common in airliners.


texts: How to apply the TO/GA time and EGT limits?

texts: If there is a published 1) EGT limit and a 2) TO/GA time limit, which one should be applied when the EGT is well below the EGT limit and possibly even below the 'max continuous' EGT. Particularly with consideration of terrain avoidance procedures that require climbing to a high altitude (10,000 ft) for terrain avoidance.


texts:
I was going over Special Visual Flight Rules (SVFR) with my instructor recently and he told me that he has only requested it a few times, and that it is mainly used if you are flying from deteriorating weather into improving weather. In other words, you are sure that where you are going is clear. I got thinking about it and felt that if there were ever an SVFR situation, I would most likely ground the flight (until I get my instrument rating that is).

That being said, how often do pilots request SVFR?

It seems like it would cause people to end up in situations that they can't handle i.e. weather deteriorates more instead of getting better, does this happen often?

It has been mentioned that SVFR rules vary from country to country, I am asking about peoples experiences in the USA but am happy to hear of other similar situations around the world as well.


texts: I'm designing a plane, and I have a question. What is the best place for the center of gravity, relative to the center of lift? I've heard that it's best put just behind the center of lift, but I would like a second opinion.


texts: What is the height requirement for pilots in the Philippines?

texts:
I am not an airline pilot nor do I work in the industry but I'm looking forward to. I live in the Philippines, a part of South East Asia.

My question is: what is the current minimum height requirement in the Philippines to be a private airline or commercial airline pilot?

I was at a Aviation School seminar a few months ago and one of the guest asked the host if height still mattered and the host answered "not anymore because airplane pilot seats are now adjustable". That didn't really convince me because they might be biased considering they are looking for students.


texts: What is the best option when the headwind exceeds the maximum airspeed?

texts: In a previous question, Mongo described flying his Cessna with a negative ground speed in a head wind.  In this situation, what is the correct thing for a pilot to do, if there is nowhere to land downwind and upwind ground speed is negative?  Other answers on that page show that, for very light aircraft, descending will not always get you to a low enough wind speed that you can fly forwards.


texts:
What can pilots do to minimize parasite drag?

As far as I know the effect of parasite drag really depends on the manufacturer of the airplane, but can pilots do anything about it?


texts: What is the difference between a leading edge flap and a slat?

texts:
I always thought that the definition of slat was:

"Lift modifying and adjustable wing element on the leading edge of main airfoil."

and the definition of flap was:

"Lift modifying and adustable wing element on the trailing edge of main airfoil."

However, there are also leading edge flaps, also known as Krueger flaps, and they are located on the leading edge.

What gives these elements the name of "flap"? What is the main difference to slats?


texts: How to learn the back end of flight simulators?

texts:
I am an engineering student very passionate about aviation and especially flight simulation. I want to know more about how a flight simulator is coded but unfortunately there's not much available on the internet. I want to learn the software aspect of it and would appreciate some help being a complete beginner.

If someone could assist me answering a few questions or having a discussion regarding what language to learn or what books to read, it would be of great help.

Thanks in advance!

Cheers!


texts: What are the pros and cons of practising figure-eight landings on perpendicular runways?

texts:
This is just a gee-whiz question, I have no intention of doing this nor am I trying to get anyone's blessing on this.

Part of remaining current to legally take passengers up in a plane is having 3 takeoffs and landings within the prior 90 days. There are also night requirements requiring 3 full-stop landings within the prior 90 days.

Some folks who don't fly often but want to take passengers up will hop in the plane and do 2 touch-and-goes and a full-stop before picking up their passengers. Those same folks might like to be thrifty and do those laps of the pattern as quickly and tightly as possible to minimize tach/hobbs time.

Here's what I'm getting at. If you were based out of an airport with 2 near-perpendicular runways, the winds were calm, and the traffic was nearly if not completely dead, could a pilot do figure-8 shaped landings so that the traffic patterns were halved? This would obviously involve alternating between left- and right-traffic, so those considerations would have to be made as well.

CONS/RISKS:

At an uncontrolled airport, there is some risk of surprising a plane that's not communicating. However, that risk is really not all that different than normal uncontrolled operations.

At a controlled airport, you'd have to get the controller's permission. Unless there's a specific regulation, though, I don't see why they couldn't clear you to land on 09 after taking off from 36.

PROS:

The whole point of these takeoffs and landings is to ensure that you as a pilot are safe to land on runways in general. Taking off and landing 3 times on the same runway does accomplish this, but adding another runway in there makes the currency more "general", especially if there are differing runway surface materials, lengths, widths, etc...

I did assume the winds were calm, but if the winds were something like 5kts, you would also get the experience of having a crosswind. This is great because you might be taking your friends to an airport with one runway, which could mean you have no choice but to deal with a crosswind component. You don't want your first shot at this in 90 days to be with friends in the back!


texts: Did airlines fly their aircraft slower in response to oil prices in the 1970s?

texts:
Modern airliners generally have lower cruise speeds than those of comparable aircraft from 40 years ago (the venerable Boeing 737 seems to be something of an exception; it has always had a more leisurely cruise speed).

Airlines had to respond much faster to the oil crisis than manufacturers could - to what extent were airlines able to economise on fuel consumption by flying more slowly, and what sort of margin was available to them at cruise (and by extension, what sort of margin is available in modern aircraft, should economic factors drive operators to seek lower fuel consumption by flying more slowly)?


texts: Are you required to record flight hours of serialized parts?

texts: Is it a requirement to record/maintain flight hours for serialized A/C parts? I have searched the FAA website with no luck.


texts: Are multi-crew operations in a single-pilot aircraft counted towards ATPL requirements?

texts: I thought that you had to perform all your ATPL multi-crew time in aircraft with a certificated minimum of 2 crew, but I've heard of some pilots using time in single-pilot aircraft towards their EASA ATPL licence. Is this true? If so, could someone explain how is this possible?


texts: What is the plane on the Home Bush Bay Funsaver EP cover?

texts:
Found this CD I had in 1997 and just bought it again as it got lost.

There is an aircraft which I cannot identify:

the sticker on the propeller leads to a propeller manifacturer called Avia
guess its a double engine plane with retractable landing gears
the picture on the CDs are invertet so I inverted the colors
guess it's a combustion engine, not a jet
the vent slots are pretty similar to Zlin planes but could not find a model which fits to the pictures

Solved: it's an Let L-200 Morava, thanks for your answers!


texts:
I would like to understand the design philosophies of aviation embedded systems that provide real time control and instrumentation like EICAS/FMS/GPWS & TCAS.

What kind of embedded OS platforms do they use? VxWorks Linux, RT Linux
etc..?
Is there a specific design philosophy in Computer Science that is used for ensuring real time behavior? (Just like fault tolerant hardware for fail proofing?)


texts: Does the routine flown by the Thunderbirds in the F-16 feature true sustained knife-edge flight?

texts:
Does any aerobatic routine flown by the USAF Thunderbirds in the F-16 feature true sustained knife-edge flight?
By "true sustained knife edge flight" we mean that the aircraft is maintaining a constant altitude in a 90-degree bank.  It is not merely flying a ballistic trajectory, which would be manifested by the vertical speed steadily becoming less positive or more negative.
If so, is any special modification to the flight control system required to make this possible?
This question is motivated by the related ASE answer https://aviation.stackexchange.com/a/35986/34686 .


texts: Is it technically feasible to dampen the control stick in an Autogyro?

texts: The control stick in a gyrocopter is too wobbly for a glider pilot's liking. Is there a way to dampen the stick in a Gyrocopter [Eg. the Air command] to make it feel as smooth and light as one would in a Sailplane; without adding too much weight....


texts: What is the maximum number of planes a controller can control?

texts:
In a small and un-busy airport, the same controller can be the ground and tower at the same time. If the sector is un-busy (e.g. late at night), he may also be a sector, ground and tower all at the same time. At busy airports of course, ground and tower are two persons. Sometimes even ground is split to "Ground South" and "Ground North".

So there is a threshold where the communication has to be split into two, either because the frequency would be too busy (only one person can talk on the frequency at any time), or there are so many planes that a controller would start making mistakes.

What is that threshold? (Is it a concrete number, or some other conditions which can be objectively determined?)


texts: Would a 19,000 ft descent in 6 minutes feel noticably different to passengers?

texts:
In July 2008 a Qantas 747 suffered decompression at 29,000 ft and the pilots then descended to 10,000 ft in the space of six minutes . More details here : wikipedia.org/.../Qantas_Flight, 30 .

I'm curious to know if you're in a large aircraft descending at that rate would there be a strong sensation of descent for the passengers? Would the plane be angled downwards in a way that wouldn't normally happen or some other sensation not normally experienced when travelling on large civil aircraft?

I appreciate that in this case the masks were down and there might have been noise/wind associated with the actual incident, so clearly it did feel strange to these passengers, but if the descent was done as a test at that rate would it feel strange?


texts: More than one runway with the same heading. How are they labelled?

texts:
Given that runways are labelled by magnetic heading. What happens in airports that have more than one in the same direction?

How are they labelled?

Are there any such airports?


texts: What is the history behind CAR 105.01(2)?

texts:
Canadian Aviation Regulation 105.01(2) states:

"No person shall conduct an aerial sightseeing flight, or any portion of an aerial sightseeing flight, in the control zone of the Québec/Jean Lesage International Airport unless the flight commences at that airport."

I find it odd that this is a law, and not just a NOTAM.

Does anyone know why this was added to the CARs in 1998?


texts: Does 14 CFR 91.146 (Charitable Events) apply if the pilot does not seek compensation or hire?

texts:
I'm at a loss between regulations §91.146 (Passenger-carrying flights for the benefit of a charitable, nonprofit, or community event.) and §61.113 (Private pilot privileges and limitations: Pilot in command.)

§91.146 contains language that allows a private pilot (who meets 500 hour requirement, among other items) to operate as PIC for a charitable event. The language emphasizes that if the event doesn't meet the charity requirement, it is to be considered commercial.

Do these restrictions under §91.146 / §61.113(d) apply if a pilot is willing to PIC under the criteria of §61.113(a) and cover all expenses of the flight?

  §61.113   Private pilot privileges and limitations: Pilot in command.

  (a) Except as provided in paragraphs (b) through (h) of this section,
  no person who holds a private pilot certificate may act as pilot in
  command of an aircraft that is carrying passengers or property for
  compensation or hire; nor may that person, for compensation or hire,
  act as pilot in command of an aircraft.

  ....

  (d) A private pilot may act as pilot in command of a charitable,
  nonprofit, or community event flight described in §91.146, if the
  sponsor and pilot comply with the requirements of §91.146.


texts: Who manufactured the 737 MAX flap track fairings?

texts: I can't seem to find the information online, would anyone of you know where / by who the flap track fairing for the B737 MAX is produced?


texts: Why do extra flight crew members sit in the cockpit during takeoff/landing?

texts:
I have observed this many times for long haul flights where they have extra cockpit crew: during takeoff they all gather in the cockpit and then disperse to their rest areas. They meet again somewhere halfway to hand off flying responsibilities and then gather again before landing. Usually approximately half an hour after/before takeoff/landing.

One way of thinking is, if you are going to rest, rest from the beginning. Just take over your duties when your turn comes up. Why even bother visiting cockpit if you are going to be there only for first 30 minutes or so of the flight.

I understand takeoff/landing are most critical phases of the flight where things can go wrong. But then airline have deemed that whoever is flying the plane at that point is fully capable of flying or in other words fully accredited crew is managing the flight.

Is there any other reason why all the crew has to meet in the cockpit during these phases?


texts: What are the rules for "see and be seen" when you suspect a potential conflict in class G airspace?

texts:
The airfield I learned to fly helicopters at is in uncontrolled airspace and has an air/ground radio service only.  It has a main runway, 07/25 and a secondary runway only used in high x-winds, 13/31.

All fixed wing circuits are to the North so fixed wings will fly right hand circuits when operating Westerly and left hand circuits when operating on the Easterlies.  Helicopter circuits are always to the South so the reverse is true.  This works well and keeps fixed wing traffic separated from helicopters.

Therefore, there is no "dead side" since the Southern leg is the downwind for rotary and the Northern leg is downwind for fixed wing.

Once, when preparing for take off from runway 25, I heard a call from a fixed wing announcing they were about 7 miles to the East and would "join dead side".  The A/G operator reminded the pilot, who clearly wasn't one for reading the relevant publications, that there is no dead side and advised them to make a standard overhead join.  We were operating to the West so my circuit would be left hand to the South.

The next call I heard from them was on the downwind leg when the pilot announced "descending dead side".  The operator reminded them that there was no dead side and more insistently instructed an overhead join.

I am now at 1,000 feet on my downwind with an aircraft I suspect is in front of me heading towards me and descending!  Referring to the plate, I am heading roughly East to the South of the road marked "A303" at the bottom of the plate.

I took 3 actions;  I made a position call of "downwind South", increased my height to 1,200 (I figured they were likely to have joined at 1,000 feet) and switched on the landing light.

I can't find any rules of the air or rules of thumb to help in this situation.  Are there any?  Is there anything else I should have done to help to avoid a conflict?

I never did see the other aircraft and I knew from the pilots actions and their lousy use of the radio that they were inexperienced or incompetent and I didn't go looking for them when I was back on the ground to "share a little wisdom" with them.


texts: When sizing a powerplant for a GA aircraft, how do you estimate the power required for other electrical systems?

texts:
When designing a GA aircraft, I have sized a powerplant (in kW) needed to run the plane on its mission. However, this does not consider the power needed for avionics, de-icing, etc. How do I approach finding the numbers for these systems? Are they significant?

For de-icing, this study from Hamburg University shows some example power consumptions from 23 KW/m^2 to 44 KW/m^2. For sizing an engine, should I just assume the thrust will have to be decreased in order  to accommodate de-icing?


texts: Wind speed over which a Canadair fire fighting plane cannot safely fly?

texts:
We recently had some forest fires in Athens, Greece while the weather was very windy. The news said it had 8 beaufort of wind speed (34-40 knots, 38–46 mph) and in these conditions it's dangerous to fly the "canadairs" (I think we have Canadair CL-215 and Bombardier 415).

Is this true? What is a wind speed over which one wouldn't want to fly such a plane?


texts: How does the Harrier avoid engine damage when operating from dirt fields?

texts:
The Harrier V/STOVL jet was designed in order for its users to be able to retain a functional air force even with all conventional airports destroyed; to this end, it can take off from, and land in, essentially any space large enough for it to fit into, potentially including unpaved dirt pads.

Unlike most jets designed to be capable of rough-field operations, the Harrier has no mechanism for preventing engine dirt ingestion, and, indeed, ingests considerable quantities of dirt and dust when operating from dirt fields:

(Image by @KeithS here at AvSE.)

How does the Harrier avoid engine damage from dirt ingestion during rough-field operations?


texts:
I've just read this article about the disappearance of QZ8501 and was surprised by the following statement:

  Even with automated beacons (we can assume these weren’t used, weren’t
  on board or were intentionally disabled) and EPIRBs, losing an
  aircraft is actually not that difficult.

Now, is it?

I was under the impression that if Breitling can make a watch with a 406 MHz distress beacon, a €70 million aircraft must surely be equipped with an automated ELT that can start to transmit automatically and whose signal can be picked up by [LE/GE]OSAR.

As it seems, US-registered civil aircraft are not required to carry 406 MHz ELTs while aircraft registered in Australia must be equipped with ELTs that operate on both 406 and 121.5 MHz (see the same reference).

Can you shed some light upon what is the current state of ELT regulations, how ELTs fitted to commercial aircraft operate in case of distress (automatic/manual?), what are the relevant regulations for EU-registered aircraft, and how can one lose an aircraft when all these systems operate?

I don't buy that “losing an aircraft is actually not that difficult” if all available technology is used (even assuming little redundancy and an adequate price range).


texts: Can a pilot use legal psychoactive cannabinoids?

texts: How do the FAA and airline companies treat pilots using substances like Delta-8-Tetrahydrocannabinol on their down time? Like CBD, Delta-8-THC is a legal derivative from marijuana.


texts: Can a commercial pilot transport friends for free?

texts: Is there anything in the FARs that would prohibit a commercial pilot from doing multiple trips to ferry friends to an event in his/her personal aircraft assuming that the friends did not provide any compensation?


texts: Are checklists always written in English?

texts:
Are checklists normally written in English? If pilots are native speakers in another language, is it possible/legal for them to use the translated version of the checklist?

This may be different for the small private aircraft and commercial airliner. Please cover multiple cases when possible.

Soviet Union pilots probably used Russian for checklist. However I ask about open, developed countries (Germany, France, etc) and planes that are used all over the world.


texts: Phoenix Area Helicopter ATC: What is "Hee-lah" (Gila?) One, and what is the 101 transition?

texts:
I've been listening to the Phoenix Tower LiveATC feed, and I hear references to "Hee-lah" (Gila?) One and the 101 transition with helicopters (see audio files below):

Angel-Five

TV-3

TV-15

Does anyone know what these are? References would be appreciated if possible. Thanks!


texts: When were airbrakes used for the first time in aviation?

texts: I would like to have some information about the history of airbrakes.


texts: Do pilots using an electronic flight bag need to carry paper charts?

texts:
If a pilot uses an electronic flight bag (say, an iPad with ForeFlight or WingX), are they required to carry paper charts as a backup?

Do different rules apply to operations under Parts 91, 121, and 135?


texts: Where is the first Boeing 747-8 ever built stored at today?

texts: I have tried many different ways to try to find where it is stored, but have had no luck.


texts: Should I use given resolution or calculate resolution based on the max range and number of sig bits?

texts:
In ARINC429, Should I use given resolution or calculate resolution based on the max range and number of sig bits given?
ForeExample, to calculate Ambient Static Pressure (Label-203, Equipment ID - 10A),
Given Range (Min to Max): 1.5 to 20
Given No of SIG. bits: 11
Given Resolution: 0.016
Calculated Resolution:
MAX RANGE / 2 ^ (No of SIG. bits)
20 / (2^11)
20 / 2048
= 0.009765625.

Question 1: What will be the Ambient Static Pressure value if all the 11 bits are 0.
Question 2: Should I use given resolution or calculated resolution for my LSB value?


texts: Do the CAA's recent changes to medical requirements mean I wasted my time getting a medical?

texts:
I'm studying ab initio towards an EASA PPL. To be ready for my first solo, I obtained a class 2 medical certificate earlier this year. I had to take a day off work to do it and spend some cash that could have paid for flight time! Recently, the CAA has announced changes to the medical certificate requirements, aimed at reducing the need for private pilots to see an AME, but the announcement is not entirely clear to me.

Assuming these changes come into force before I first fly solo, could I have obtained an EASA PPL (and used all the privileges of that licence) without having obtained the class 2 medical certificate? If so, and assuming I don't intend to progress to a CPL or ATPL, is there anything else I need my certificate for, or any reason to renew it when that comes up in five years?


texts:
Both the C-141 Starlifter and C-5 Galaxy have T-tails, where the horizontal stabilizers and elevators are mounted on top of the vertical fin rather than on the sides of the aft fuselage.  T-tails are usually only found on aircraft where the real estate on the sides of the aft fuselage is taken up by engines (Il-62, 727, DC-9, Tu-154, etc.), as the T-tail configuration has the serious disadvantages of

needing a vertical stabilizer strong enough to carry the entire weight of the horizontal tail plus the considerable downward aerodynamic forces generated by same, making for a considerably heavier (and, thus, less fuel-efficient) airframe,
causing maintenance difficulties, as it's harder for the mechanics to inspect and repair something that high up (this was an indirect cause of the crash of Alaska Airlines Flight 261), and
being susceptible to an extremely dangerous "deep stall" condition, where, at an angle of attack slightly past the stall point, the disturbed wake from the aircraft's wings blanks out the horizontal tail, causing a total loss of pitch control and making recovery essentially impossible.

The C-141 and C-5 have conventional wing-mounted engines, yet both have the tail configuration of an aircraft with fuselage-mounted engines; why is this?


texts: When did airlines start using seat belts for passengers?

texts: When did airlines start using seat belts on passenger flights?


texts: Wing pitching moment decomposition into two terms

texts:
Summary: Assuming constant angle of attack $\alpha$, speed $V$, and lift $L$ applied at the center of pressure CP (whose position is $x_{CP}$), the distance $(x_{CP} - x_O)$ between the moment reference point $O$ (whose position is $x_O$) and $CP$ determines the sign (positive, negative or zero) of the pitching moment as long as $L\neq 0$:

$$M_O = (x_{CP} - x_O)L$$

However, the moment $M_O$ depends on $\alpha$, i.e. $M_O=M_O(\alpha)$, since changing $\alpha$ while keeping the reference point $O$ position constant, varies the magnitude $M_O$ since both lift $L$ and the position $x_{CP}$ vary.

Interestingly, when $O=AC$ and $x_O=x_{AC}$, the moment does not change with changing $\alpha$:

$$ M_{O}(\alpha) = M_{AC} = (x_{CP} - x_{AC})L = constant$$

We can move lift $L$ from its application point $x_{CP}$ to point $x_{AC}$ while adding a constant free pitching $M_{AC}$ whose magnitude is $(x_{CP}-x_{AC})L$. The moment $M_{AC}=0$ for symmetric wings and $M_{AC}\neq0$ for cambered wings.

In the case of a cambered wing, the equation
$$ M_{AC} = (x_{CP} - x_{AC})L$$ predicts that $$M_{AC}=0$$ when lift $L=0$. However, we know that a cambered wing has a a constant nonzero moment $M_{AC}$ for any $\alpha$ even when $L=0$ at the zero-lift $\alpha_0$. How do we transform the equation for $M_{AC}$  so it becomes equal to the sum of two terms, one solely due to camber and one solely due to lift:
$$ M_{O}(\alpha) = M_{AC} = (x_{CP} - x_{AC})L= M_{camber}+M_{lift}$$

where the term $M_{camber}\neq 0$ for any $\alpha$?


texts: What is a land and hold short clearance (LAHSO)?

texts:
I was reading this question and I want to know what this term means.

  land and hold short clearance


texts: What and when was the first gyroscopic flight instrument introduced?

texts:
One of things which consistently amazes me about flight is the exceptional progress in the early decades of flight - especially in terms of avionics. Wikipedia tells me that the first ILS landing was in 1938.

I'd like to understand more about the early development of gyroscopic flight instruments - in particular, what the first instruments like? When were they first put to use?


texts: How should I establish initial contact with ATC after being handed off by another controller?

texts:
What is the proper way to contact a new air traffic control facility after you have be instructed to do so by the controller you are currently interacting with?

As a practical example: Here in Northern California, I will typically contact NorCal Approach on 125.4 to get flight following. If I travel ~50 miles north, approach will tell me to contact Oakland Center on 132.2. When I contact Oakland Center, what is the proper way to announce myself?

My original CFI instructed me to say:

  Oakland Center, Tail Number, with you on 132.2

However my new CFI, says that is incorrect and in fact alluded to the idea that perhaps it was ridiculous. His instructions were:

  Oakland Center, Tail Number

However, the two times I had used the more abbreviated version above, the controller seemed unsure of my intentions and I had to state (in plain english because I was not sure how to communicate this) "NorCal Approach just sent me over to you".

What is the proper way to handle this situation?


texts:
I was reading the APS-3200 training manual (pg 268) and faced this part:

What's the starting envelope of APU?
What does mean "Normal start throughout the operating envelope: minus 300 m to 11900 m (minus 1000 ft to 39000 ft)"?


texts: Is it possible to perform a spin recovery in IMC?

texts:
In other words, after some training, is it possible to recovery a spin solely by relying on instruments?

If using a vacuum-pump traditional attitude indicator, I assume the answer is no, since there are limitations for its pitch and bank indication. What about an AHRS-based attitude indicator? Is it capable of matching 360° attitude changes in all directions, and catching up (without delay) with fast rolls? Can it filter out vibration well enough, so that a pilot is able to perform a spin recovery maneuver?


texts: Unusual Traffic Ene 68 degrees over Dorset United Kingdom - No strobes, green or red just solid white lights

texts:
I have spotted a line of traffic 1 minute apart, at least 12 objects, with 3 objects to the left and right of the main line of traffic.  Clear night, no pollution, no noise, whit solid lights only.  I know what satellites look like in the night sky and that is exactly what this looked like in terms of height and speed but there was a stream of them equally distanced apart with 3 random ones to either side of the line of objects.  There was no strobe, the white light of each was showing form the front, side and rear. No green, no red.

I have never seen anything like this, nor have I ever posted anything like this but please if you know what this was let me know.  Can re positioning aircraft because of covid-19 fly with no strobing or colour lights etc?  Is it military?

I filmed this tonight 29th March over southern UK at around 2120hrs.  Many thanks.


texts: What is the purpose of including sea level pressure and temperature in a METAR?

texts:
In a METAR such as this one:

  KGOK 161553Z AUTO 18011KT 4SM BR OVC007 07/05 A3011 RMK AO2 SLP201
  T00670050

Translated to:

  Jan 16, 1553Z, Automated. Mist, Wind from 180° at 11 knots, 4 statute
  miles visibility, Ceiling is Overcast at 700 feet, Temperature 7°C,
  Dewpoint 5°C, Altimeter is 30.11. Remarks: automated station with
  precipitation discriminator sea level pressure 1020.1 hectopascals
  hourly temp 6.7°C dewpoint 5.0°C

Why would I want/need to know, or what would I do with, this information in the remarks section:

  sea level pressure 1020.1 hectopascals hourly temp 6.7°C dewpoint
  5.0°C


texts: Are lockwires still preferred over self-locking nuts and other ways of bolted joints` safety?

texts:
I've watched some of the lockwiring videos and if I understood it right then there are two most widely used ways of ensuring that a bolted joint does not get loose:

Lockwire
Self-locking nuts

Difficulties and costs of maintaining the lock-wiring are obvious. My intuition says it only has to be used as a last resort when no other way is available. Nevertheless any aviation junk yard says my intuition is wrong. Lock-wires are everywhere in the old gas turbine engines. My question is:

Do they now use other methods of bolted joints` safety in gas turbine engines (jam nuts and locking washers in particular)?


texts: How dangerous is to take-off and fly with snow on the wings?

texts: I have seen a video of a commercial aircraft taking-off with snow on the wings. I wonder how dangerous it is to take-off and fly with snow on the wings.


texts: Would this work to reduce turbine engine spool times?

texts:
In this answer to a question about reducing engine spool-up time, Peter Kämpf said:

  When more thrust/lift is needed, the pilot adjusts pitch and fuel flow to set the desired thrust/lift level. Since the engine is already running at top speed, the change is not delayed by inertial effects.

It seems to me that landing mode or critical mode switch for the engines which would cause the FADEC to spin-up the engine and control power by fuel flow instead would eliminate the lag and increase the likelihood of survival during critical flight regimes.

As an example, encountering a micro-burst during landing will leave the plane wanting power as it flys out of the burst and has a tail-wind, often at low power and low altitude. If, in that situation, the pilot applying additional throttle increased the fuel flow and gave immediate power instead of having to wait for the engines to spool, it seems that would be very advantageous.

Have I understood the concepts correctly, and, if so, what drawbacks to this system might I be missing?