texts:
I'm just finishing up Air Force Pilot Training (UPT).

The day after graduation we are issued commercial certificates for SEL and MEL.

The military does things pretty different from the civilian world though.  I don't have any sort of physical log book of my military training in the T6 and T38.

Can I go rent a "high performance" "complex" airplane after I get my FAA commercial?  I don't have any logbook or endorsements, but all of my training would surely meet these requirements. The T-6 was 1100HP, and the T38 is an after-burning, supersonic jet.

I was hoping to take my family out flying over the holidays in a Cessna Twin.

I was home a few weeks ago and went into a local FBO and asked about renting a twin over the holidays.  They told me I didn't have the proper training in a "complex" "high performance" aircraft (they really acted like they didn't believe I was an Air Force pilot).

It almost seems like there's something about the civilian world that I'm not in the loop on.


texts: Why was Energy Maneuverability theory not applied to the F-14?

texts:
In John Boyd's (declassified) 1966 Energy Maneuverability [PDF] report, studies were done on the F-4 and on the MiG-21 and those studies were applied to the F-15, F-16 and F-18. My questions:

Why wasn't this theory applied to the F-14?
Was this due to the fact that it was a carrier-based aircraft?
Or did it have to do with the variable sweep wings that would change how the energy bleed changed with changes in the sweep angles at different speed?

The F-14 was developed well before the theory of Energy Maneuverability was published, but improvements were made in F-14s till the late 1980s. With the early development of F-15s the Energy Maneuverability theory was utilized to improve its performance but same wasn't done or at least mentioned anywhere.


texts: Is Ground Direction Finding commonly used?

texts:
I've recently come across the concept of Ground Direction Finding. My (limited) understanding of it is that it is a system that allows you to see where a VHF transmission is coming from. I gather it was used in the Earhart-era of aviation for navigating, and could be a rudimentary air-traffic control system where there is no radar.

I think it's still used these days in boats but what about aviation? And is my understanding of it essentially correct?


texts: How does the relative wind on a propeller, strike the blade from behind (the non camber side)?

texts:
This may be a stupid or simple question, although any help is appreciated! :)

If possible, please answer without mathematical terminology. So I understand the concept of the blade increasing air momentum at the front, thus creating lower pressure, and I also get that the blade acts as an airfoil, lower pressure at the top, and higher at the bottom thus pulling it forward, and producing thrust.

My main issue is that I can't visualize how the relative wind physically travels behind the camber side, and hit the back side of the airfoil like in the diagram? Wouldn't it hit directly on the camber side if it's moving forward, not travel below, and strike it from the back? If someone can explain, that would be amazing!


texts: Are airliners' cruising altitudes we know indicated or true altitudes?

texts: Are airliners' crusing altitudes, which commonly range from 25000 to 45000 feet depending on various conditions, indicated altitudes or true altitudes? If they are indicated altitudes, what are the range of cruising true altitudes?


texts: What is the correct ATC phraseology in the US for an immediate - no delay takeoff?

texts:
Just wondering - what's the correct ATC phraseology for a takeoff where a plane does not stop first after lining up with the runway centerline before starting their takeoff roll?

Redwood five-two-six-three, runway three-zero cleared for takeoff, no delay.
Redwood five-two-six-three, runway three-zero cleared for immediate takeoff.


texts: What is the absolute ceiling of a 737-200?

texts: We're trying to find the official absolute ceiling for the 737-200 for a school project.  So far have only been able to maximum and service ceilings for this craft. Can anyone point us to the correct information for absolute ceiling?  Thanks!


texts: Why do certain aircraft's landing gear tilt up?

texts: Why do the main landing gears of aircraft like the A330, 777, 787, etc tilt up? This does not happen with the 767. Interestingly, for the 747, the inner landing gear does not tilt up while the outer landing gear (under the wing) does. Why does that happen?


texts: Where can I find an aircraft's year of certification (airworthiness certificate)?

texts:
Is there a way to pull a list of all certified aircraft (of course only valid certifications) including the year of certification please?

For example I am actually trying to identify when CRJ200 PF was certified ?

thx


texts: Aerodynamic advantage of blunt noses and WHY (subsonic)

texts:
Compared to a sharper conical nose, a blunter conical nose is aerodynamically superior in subsonic flight. My question is why. I've read a lot about this and allegedly:

A blunter nose accepts a wider range of angles of attack without sideways airflow across it, which would cause additional drag that is avoided.

It would appear that airliners have blunter noses because they fly at a wider range of AOAs and gliders have sharper noses because they fly at a narrower range of AOAs. However...

At optimal AOA, the form and skin friction drag is also lower. I don't understand why!

According to this, a blunt nose is aerodynamically superior even when flying at the optimal AOA, but then why do gliders, which obviously value aerodynamics above all, always have relatively sharp noses? According to some descriptions, a hemispherical cap is the optimal shape for decreasing form drag and skin friction drag, but I haven’t found any description of why the first is true and the second is often motivated with hemispherical caps having the lowest surface area to volume ratio, but a conical cap of equal height has a lower surface area relative to the radius! In other words, if we were to design a new airplane, why wouldn't we sharpen the nose closer to a point instead of blunting it closer to a hemisphere, only considering aerodynamics?

Edit: yes, this is a unique question because I’m asking why and specifically why form and skin friction drag of a blunter nose is smaller than for a sharper nose, challenging intuition.

Edit 2: basically, why does No 2 in the following have less drag than No 5?

According to the image (I’ve yet to read the source, I’m on it!) there’s less pressure drag, but according to an answer by aeroalias to a related question, there’s less friction drag:
Why/when is the blunt nose better?
Which one is it? Both? Which one is most relevant? Or are both irrelevant in reality? Peter Kämpf’s answer makes no mention of either alternative, only arguing about the AOA and stagnation point.


texts: What are the lateral sensitivities of GPS approaches?

texts: What are the lateral sensitivities of each of the WAAS and LNAV approach? Is the lateral sensitivity of WAAS the same as that of the localizer, which is 3 to 6 degrees? What about the LNAV approach?


texts: How frequently are airline pilots switching between aircraft types (e.g. Airbus, Boeing, etc)?

texts:
Are pilots at Airlines typically assigned to fly a single Type in a given month / year or do they get switched routinely between multiple types of aircraft as per scheduling convenience?

i.e. Is it common to, say, fly a B-747 & then return flying a B-777 etc.

How about more extreme changes like switching between Boeings & Airbuses or Turbojet / Turboprop etc.?

I guess that begs the question whether pilots typically are certified & current across multiple Types? How common is this?

I'm looking more for comments about what is operating practice across airlines rather than a hard rule, which I guess does not exist.


texts: Is special permission required to take off from a field within restricted airspace?

texts:
I had a question about restricted airspace that I wanted to clear up before resuming my training Sunday; you know, to maximize time in the air.

The airport I am training at is KMRH and it's surrounded by lots of restricted/military airspace/MOAs. From what I have read, restricted airspace requires permission to fly in; however we have never done that, we just call up on Unicom and state our intentions to other pilots.

If someone here could look at an online sectional of the area and get an idea of what I am saying and attempt to explain this to me it would be very helpful. If nobody can crack through my thick skull, I can always ask my CFI!


texts: What happens to EGT after a bird strike?

texts: I just watched the movie "Sully", and I really enjoyed the effort put into making the movie as accurate as possible.  As I'm working towards my PPL, I decided to apply some of my new aviation knowledge when watching the movie.  I especially focused on the center MFD.  I understood everything I saw, except for the Exhaust Gas Temperature (EGT) readings after the bird strike.  I noticed that Engine Pressure Ratio (EPR) and N2 fell, but EGT stayed in what looked like roughly the same position.  I would have expected EGT to fall after the bird strike destroyed the engines, but it didn't.  Is this normal?  Did the flames seen coming out of the engines cover up a fall in EGT?


texts: How can a modified ramjet produce static thrust without a turbine?

texts:
A big selling point of the ramjet is its absence of moving parts (hence why it can be translated as "statojet" from other languages). However, an even bigger drawback is that a ramjet cannot produce static thrust, thus a ramjet-powered aircraft cannot take off by itself.

The early Leduc 0.22 and Griffon prototypes solved this by adding a coaxial turbojet. This was further refined with the Pratt & Whitney J58 turboramjet that powered the SR-71 Blackbird.

The problem is that by solving the no-static-thrust drawback, adding a turbojet negates the no-moving-parts selling point.

There are missiles that use solid fuel rockets to solve the problem, using the exhaust of the rocket to compress the air in the ramjet, which is sometimes referred as a ramrocket. However, there doesn't seem to be aircraft using this kind of engine, and missile engines have quite different constraints.

Is there an aircraft engine, working or theoretical, that works as a ramjet in cruise mode, can take off on its own power (without requiring ground installations or a detachable first stage/mothership), and doesn't have the many complicated moving parts of a turboramjet? What are its expected characteristics? If not, what are the showstoppers?

And why can't we simply inject some oxidiser (for example WFNA) to produce static thrust?


texts: How much does it cost to give an airliner a fresh coat of paint?

texts:
Just a random thought I had: the weather gives a jet's paint job a battering; meaning they need to be resprayed approximately once every 5-10 years. (See How often is a passenger jet aircraft painted?)

Roughly what might a paint job for a 777 like the one shown in the YouTube video below, cost an airline?

Bonus: I believe afterwards that the weight of the plane has to be recalculated, so as not to affect weight-and-balance. How is this calculation done?


texts: What is the weight of the bulletproof cockpit doors of a Boeing 747?

texts: What is the weight of the bulletproof cockpit doors of a Boeing 747 built prior to 9/11? Do the doors weigh the same for later models, like the Boeing 747-8 specifically? How many fewer passengers do they have to carry in light of the added weight?


texts: Can passenger distribution cause a parked airliner to tip?

texts:
This question on Travel.SE recounts a situation where a passenger, about to disembark from a commercial airline flight, was asked by a flight attendant to wait for other passengers to "catch up".

This answer suggests that if too many passengers were to disembark from the front, while passengers at the back remained at the back, the plane might tip backward; and that the flight attendant was acting to avoid this possibility.

Is this really a risk on modern airliners, or even regional jets or turboprops?  (The aircraft in the question at hand was a 737.)  Are flight attendants trained to redirect or hold passengers in order to avoid it?

I saw Is passenger weight distribution important on a commercial flight? but it is about the aerodynamic effects of passenger distribution, which are not relevant when the airplane is parked on the ground.


texts: Is required that your alternate airport has approaches other than GPS approach?

texts: I start to read AIM and AC90-105A about alternate considerations.If I have GPS(TSO-129 let’s say),Can I file based on a GPS-based IAP at the alternate airport,and my alternate airport only has GPS approach?


texts: What are CP-like codes or designations after SAS or Scandinavian flight attendant names?

texts:
While browsing through Wikipedia I came across this photograph:

It's description says (emphasis mine):

SAS DC-9, interior of cabin, service on board. Air hostess Kirsten Andersen and Birthe Bymose both CPHCV serves lunch to Elisabeth Pinske CPHKA and Torben Wittrup CPHZC-S. 1960s

I was wondering what these codes are used for or that is their meaning.


texts: Why is the S-duct intake on the Tu-154 uniquely oblong?

texts:
Is there an advantage to the oval/elliptical shape of the Tu-154's S-duct intake? It appears to be taller and an overall different shape than the side-mounted cowlings.

This doesn't appear to be a feature common to trijets or even on those with S-ducts.

EDIT: Upon further research, it appears the 727-100 had an oblong intake (Thanks Terry!), and the Hawker Siddeley Trident had an entirely unique shape. So my original premise of the Tu-154 being "unique" no longer holds. I am still curious about the implications of the different designs.


texts: If the stick pusher fails on a Bombardier Q400, what happens to the c.g. limitation?

texts: If the stick pusher fails on a DHC/Bombardier Dash-8 Q400, what happens to the center of gravity limitation?


texts: How does the raked wingtip of the Boeing 787 work?

texts:
The wing tips are very different on these airplanes. The wingtip on a Boeing 787 is a sharp triangle, while the wingtip on a Boeing 737-300 is flat.

British Airways Boeing 787-8 G-ZBJC wingtip | by StephenG88 (source)

Why is the wingtip on the Boeing 787 different from that of the Boeing 737?


texts: Why is the aviation industry taking so long to move away from the tube with wings model?

texts: The industry is spending billions on maximising fuel efficiency and reducing other costs associated with the tube-with-wings model. When will novel designs like semi-dirigible and lifting body arrive, what's the delay, surely the industry will be forced into a corner before the latest batch of airliners are due for retirement?


texts: Do mechanical attitude indicators have rotation limits?

texts:
Do mechanical attitude indicators have limits to the rotations they can display?
Wondering since gyros suffer from gimbal lock when two axes become aligned (e.g., at 90 deg pitch, if you were doing aerobatics?)
Digital gyros suffer from gimbal lock as well, though the cause is now the mathematics which loses one degree of freedom when two axes become aligned.


texts: Simple explanation for static and dynamic pressure?

texts:
From what I understand, static pressure is just the pressure of still air and acts perpendicular to the airflow and surface. An airplane will feel static pressure regardless of whether it is moving or not. If there was airflow moving through a pipe, then static pressure is the pressure exerted on the walls of the pipe.
On the other hand, dynamic pressure is the pressure that results from the motion of air, or its kinetic energy. It acts parallel to the flow of air. Would it be appropriate to say that dynamic pressure is the pressure exerted on the windward side of a flat plate in the pipe like this:

If this illustration is correct, then does that mean maximum dynamic pressure is felt by a surface when it is perpendicular to the flow?


texts: Why do pilots' seat covers almost uniformly use sheepskin?

texts: While browsing this answer I noticed the sheepskin cover and recalled that I couldn't remember a cockpit that didn't have them. It's not entirely surprising that they're used, but I am surprised that they seem to be always used. Are they indeed ubiquitous? Are there any competing alternatives? Do modern airliners use them as much as GA/military/sport aircraft?


texts:
So, I spotted another weird METAR from the same place that spawned the first one I asked about (it's a USAF base if you're wondering what kind of 'drome it is):

  K... 060846Z 00000KT 10SM OVC002 18/18 A2995 RMK AO2A SLPNO ALSTG ESTMD $

While I can reckon that the barometric pressure sensor there's on the fritz (again) from the SLPNO and the $, they also have the "ALSTG ESTMD" remark on there.  While the estimate looks to be not too far out, or at least more reasonable than the completely bogus figure from last time, it raises a question: how are they estimating an altimeter setting in the absence of the AWOS's barometer?  Or does it just mean that their backup barometer isn't as good as the one on the AWOS, so the altimeter setting might be a few ULPs out?


texts: The pressurization in the cabin requires the doors have their seals working properly. How do they prevent pressurized air from leaking from the doors?


texts: What is the main difference between 'continental fuel injection system' and 'Bendix RSA fuel injection system'?

texts:
While I'm studying Aircraft Engine system, I learned that there are two dominant kinds of fuel injection system : 'continental fuel injection system' and 'Bendix RSA fuel injection system'

I tried to find the main difference between those systems, and all I found out was that the former one injects fuel before the each cylinders, in the manifold(with nozzles connected to manifold valve assembly), and the latter one injects fuel directly into the each cylinders(and the nozzles are connected to a fuel divider). But I'm not sure this is true or not, since there are no part that explains the exact difference between them.

Could anyone let me know about this?


texts: On the Ka-50 coaxial helicopter, why does the bottom rotor flap up on the right side instead of in front during forward flight?

texts:
In the game DCS World flying the Ka-50, when flying forward at high speeds, the bottom rotor will flap up on the right side of the helicopter (also note that the top rotor is flapping up on the left, though not as much):

But according to this diagram:

while the maximum up-flap velocity is on the right side, the actual max up-flap displacement is in front of the aircraft. Thus, shouldn't the bottom rotor be flapping up in front of the helicopter, instead of on the right? This effect only occurs at high speeds, at lower speeds it's either not there or barely perceptible:

Is this up-flap behavior correct, and if so, what is causing it?


texts: I am 14 and want to be a pilot but don’t know how

texts:
Currently I am 14, turning 15 and live in Victoria. I have this aspiration to become a commercial pilot, but I don’t know how.

Should I start flying now? Should I get a private pilot license by 16? What should I study for VCE? Do I need to go into aviation for university, or is there a special flying university? How bad is the competition? What are all the stages of becoming a pilot starting from 15 years of age? Should i enrol in a flying school now?

I know it is a lot to answer, but I really am passionate. Thanks.

Erica


texts: How big was the F-14 fleet compared to other US carrier-based aircraft in 1981?

texts:
Back in the 80's I was away jesting about the F-14 are here to protect the carriers and the carriers to deploy F-14.

I know there are a number of other aircraft here for other purposes but I really don't know the numbers.

So for 1981 what's the proportion of F-14 to other aircrafts and also de percentuals in roles (defence of the fleet, attack, surveillance, etc).

In other words: for US aircraft carriers of that period, what was the aircraft fleet composition?


texts: What degree of elevator deflection is required to takeoff?

texts:
I've always wondered how much the elevator actually needs to deflect in order to cause rotation on takeoff for a large airliner. On videos I can rarely see the elevator moving at all.

I'd really like to know what the degree required is for a 777, but if someone can provide this for another airliner that would be ok. I presume that it depends on takeoff speed, which is of course variable, but let's see what you can come up with.


texts: How much is the minimum safe distance between two planes in-flight?

texts:
According to FAA regulations, how far should a commercial jet be away from another plane in-flight?

How about military planes? They get really close when in formations... Is there a minimum distance?


texts: How profitable is an airline shuttle flight between BOS and DCA on an A320?

texts:
I was computing the hypothetical profitability of commercial airline flights and it seems to be pretty extreme. For example, looking at the Boston-DCA shuttle, pro-rating all costs to the just the flight itself using conservative figures I came up with the following:

aircraft: A320
distance: 346 nautical miles
fuel usage: 6500 pounds

fuel: 3800
maintenance: 2000
crew: 1200
hangar: 900
insurance: 400

Total costs: 8,300

passenger count: 150
ticket charge: 200

Total revenue: 30,000

Based on these figures, profitability of this route seems to be about 350%, i.e., more than tripling your costs on every flight. Even if we allow for tickets of $100 each, it is still almost a 100% profit.

Am I missing something, or are these figures in the right ballpark?

THIS IS NOT A DUPLICATE OF long-haul flight costs. That post is for LONG HAUL flights. This is a shuttle. That post concerns a completely different aircraft with costs amortized ANNUALLY. This is post is about PER-FLIGHT profitability, not ANNUAL profitability.

ALSO: This post asks about PROFITABILITY on this route, not just costs. It includes REVENUE. I am not asking general profitability; I am asking about this calculation for profitability on the route in question using the aircraft in question (A320).


texts: Is night VMC still VMC if the underlying terrain is completely unlighted?

texts:
The whole point of visual meteorological conditions (VMC) is that there is sufficient visibility for a pilot to be able to safely fly by visual reference alone, without reference to instruments.  This, by necessity, requires a visibility of at least one to several miles, plus staying a good distance away from any clouds (the exact visibility and cloud-clearance limits depend on the jurisdiction, but all have at least some minimum requirements for these factors); so far, so good.

In many countries, however (including a lot of the big ones, such as the US, Canada, the UK, Australia, France, Germany, and New Zealand), VMC is still VMC even at night, and night VFR flight is perfectly legal (albeit with somewhat greater restrictions on who can fly VFR at night and the qualifications necessary thereto) if the visibility and cloud-clearance requirements are satisfied.1

The underlying assumption is presumably that pilots will still be able to avoid flying into the ground (in either controlled or uncontrolled manner), or each other, by reference to ground lighting and each others' anticollision lights, but this line of reasoning breaks down if you fly over unlighted terrain (of which the countries permitting night VFR flight have quite a lot), especially if it's a moonless night.  If it's well and truly nighttime, the moon is either a thin crescent or completely absent from the sky, and the terrain is devoid (or nearly so) of light sources, the ground will be almost completely invisible, with the only hint of its presence being its occlusion of the background stars, and it is difficult to imagine how one would be able to maintain terrain clearance (especially if one's aircraft lacks a radar altimeter).  Even worse would be if the stars (and moon, if present) were obscured (by, for instance, high clouds, or smoke from forest fires), in which case one would have no external visual reference at all;2 a non-instrument-rated pilot would find it essentially impossible to maintain control of the aircraft in these circumstances, just as if they were trapped inside a cloudbank during a daytime flight, and even a pilot who is proficient in instrument flight would have difficulty maintaining terrain clearance, especially in mountainous areas (which, inconveniently for our pilot, tend not to be densely populated, and, thus, are rather more likely to be unlighted than flatter terrain).

To eliminate this problem, does the definition of night VMC (in the US or any other jurisdiction) require that the terrain in the area be lighted sufficiently for it to be visible?

1: In many other countries, VFR flight is not permitted at night, and the issue therefore does not arise.

2: Unless you're low enough for your aircraft's lights to illuminate the ground, in which case you're already way in deep shit anyways.


texts: Is a ground station radio license required for UAS operations in the US?

texts:
When conducting UAS operations would a PIC or Spotter be considered a ground station or an air station?  The communications would concern a sUAS in the air, but the radio is physically on the ground.

I'm asking in the context of licensing within the United States.  As far as I can tell from reading the FCC's website, Air stations do not require a station license to operate, while Ground stations do.


texts: Why aren't there more helicopter aerobatics at airshows?

texts:
I enjoy watching RC helicopter stunts like these.  Many RC pilots are very talented, executing barrel rolls and other inversions.

How come we don't see these kind of displays at airshows?


texts: Did Boeing subcontract the manufacturing of the wings on the B757 series?

texts: If Boeing did subcontract, which company took over the manufacturing of the wings? Where were the wings made?


texts: Which Inlet Barrier Filter (IBF) is used in Airbus H145?

texts:
Inlet barrier filter (IBF) is an optional equipment in H145 / MBB-BK 117 / EC145 helicopters, which company Inlet Barrier Filters are used on them Donaldson, Aerometals etc..

The H145 Helionix / BK117 D2 Differences Training Course (airbus.com/content/dam/channel-specific/website-/us/training/…) mentions the Inlet Barrier Filter as an optional equipment, but The Airbus Options Catalogue for 2019 doesn't list an Inlet Barrier Filter for that aircraft.

The only IBF listed is for the AS350/H125 family


texts: When is a high pressure system associated with IFR/MVFR conditions?

texts:
So I've read that typically high pressure systems bring good weather and clear skies. However, for the current high pressure system we're experiencing in central USA, we're having quite a bit of IFR/MVFR conditions.

The IFR/MVFR conditions down along the Gulf of Mexico where there's a stationary front make sense, but I'm curious why there's IFR/MVFR weather from Missouri through Illinois, Indiana, and Ohio in the midst of this high pressure system.

[

Is my understanding flawed about high pressure systems? Perhaps I should really be thinking of high pressure systems as stable air masses (in this case stable, low clouds). Or are there other factors at play leading to IFR/MVFR conditions being associated with this high pressure system?

In case it's relevant (and the time/date is difficult to read on the screenshots), the conditions described were happening around 6:00Z on 2019-01-02.


texts: Can the parking brake be set on an 737-800 if the aircraft has no power?

texts: If a 737-800 has no power ('dead' airplane), is it still possible to set the parking brake on? If so, how?


texts: How do pilots see at night if airplanes don't have front lights?

texts: How can pilots identify threats ahead of them if they don't have front lights like cars?


texts: Why is the missed-approach course for the "RNAV (GNSS) - A" approach to runway 28 at ENSB shaped all funny?

texts:
Svalbard-Longyear (ENSB) has one particular approach (the RNAV (GNSS) - A approach to runway 28) whose missed-approach course is... oddly-shaped, to say the least:

(PDF by Avinor; screenshot and cropped by me.)

If the pilots can't see the runway by the time they reach SB709, they have to make a right-angle turn to the left just before reaching SB705, followed by a series of three right turns that end up with the aircraft aimed at NAXEN and its holding pattern (and flying directly over the substantial mountains immediately to the north of Adventfjorden en route).

The hockey-stick-shaped missed-approach course can't be for obstacle clearance, given that all this manoeuvring is carried out over the water - indeed, the other two approaches to runway 28 (the unadorned RNAV (GNSS) approach and the localiser approach) have missed-approach courses which each include but a single, wide, conventional turn en route to the holding patterns at the NAXEN waypoint and the Longyear NDB, respectively - so why does this particular approach have such a weird missed-approach course?


texts: FAA Commercial Pilot Knowledge Test: Sign Question

texts:
This image appears in the FAA Test Supplement Commercial Test FAA-CT-8080-1E but I am unable to find it in the AIM or the Pilot’s Handbook of Aeronautical Knowledge. I looks like a don’t taxi here pavement marking, but I’d like confirmation of my guess.

The closest I can get to an official explanation is in the AIM 2-3-2 b

  Markings for taxiways, areas not intended for use by aircraft (closed
  and hazardous areas), and holding positions (even if they are on a
  runway) are yellow.

But the examples don’t match this graphic.


texts: Is the flight management system software independent from the hardware?

texts: Is it possible to 'mix and match' hardware and software from different vendors to make a flight management system? I want to prepare a study about FMSes and I can see that there are several independent software providers, does that mean their software can be installed on different hardware platforms?


texts: Why do the N1 and N2 fans have different shafts?

texts:
This question here contains a cutaway of a jet engine (which I'm putting right....here)

Credit: K. Aainsqatsi, Wikipedia

After reading the answer, and looking over the chart, I noticed that the shafts for the N1 and N2 fans are completely separate (something I'd never noticed before.)

What purpose does that serve?  Do they always move freely from each other, or can they be locked?


texts: Why do the Lycoming HIO-360 A1A and IO-360 engines produce different power?

texts: I have just acquired an aerobatic aircraft fitted with a Lycoming HIO-360 A1A. Reading the specs on the engine I see it has the higher (8.7:1) compression of the 200hp IO-360 engines, which seem mainly to make that power at 2 700 rpm, but this one actually makes the same power (180 hp) of the 8.5:1 carburetter engines, but at higher rpm (2 900) than they turn. This was a helicopter engine originally which I think accounts for the higher rpm rating, but it seems to me wholly counter-intuitive that an engine with the same swept volume, fuel injection for greater efficiency AND more revs would make - relatively - so little power. Can anyone explain this?


texts: What is the relationship between temperature, dew point and the formation of clouds?

texts:
What can you infer from the temperature / dew point values in this METAR?

  EGJG 121630Z 09012KT 9999 SCT006 15/14 Q1015

I understand the temperature is 15 degrees and the dew point is 14, and I found this:

  The temperature / dew point spread is low, so the risk of cloud
  forming is high especially if the temperature falls.

Why is the risk of clouds forming high, especially if the temperature is falling?


texts: What is this stripe on the windshield of the Embraer E-Jet?

texts:
I noticed that there is a stripe along the upper edge of both forward windshields in the Embraer E-Jets:

(cropped from Wikimedia)
I tried to find a better picture, but couldn't find anything closer. This YouTube video clearly shows the stripe several times:

What is this stripe used for? The only thing I can think of is window heating, but these elements usually look quite different, as can be here: What is this pattern on the A350 front window?


texts: Are there experimental aircraft regulations in Germany?

texts:
The title is the question.

Are there any special regulations regarding experimental aircraft in Germany (or the EU)?

Those "special regulations" would (hopefully) be looser set of regulations in contrast to the LTF-UL regulations for ultralight planes (MTOW < 600kg).


texts: How does ATC handle changing QNH/altimeter values?

texts:
Obviously for aircraft arriving to or departing from an airport/airspace (as relevant), they listen to the ATIS and/or are given the QNH.

But what happens if that pressure changes? Even a fairly small change can make a big difference when we're dealing with 1000ft of vertical separation (which can be much less by the time we account for human margins for error).

Is the new QNH announced to the entire frequency, or similarly the change of ATIS, which each aircraft would then be expected to check? Or would it just be updated when assigning a new altitude to any aircraft already in the airspace?


texts: How are small airplanes steered on the ground if they don't have tillers?

texts: I have noticed that many small planes do not have tillers like in big aircraft.  So how does the pilot steer them?


texts: Why do many GA aircraft not have a "Both" fuel selector?

texts:
I've been trying to rack my brain around this and asked a few CFI's who couldn't give me more than "because that is how it was done", but a good number of GA aircraft save for Cessna and maybe a few others only have a Left/Right fuel selector:

Image Credit: Make Time For Flying Blogspot

To me, as an engineer, it makes great sense to have a Left/Right/Both selector such as found in most Cessna's. This lets the pilot focus on flying the aircraft rather than having to switch tanks every 30 minutes to balance fuel out. A Left/Right/Both selector isn't sigificantly more complicated than a Left/Right selector, so that leaves me wondering...

Why do GA manufacturers opt to use just a Left/Right selector valve given that a majority of GA accidents are fuel related and off-airport landings with fuel in a tank is still relatively common? Is there a safety issue I'm not seeing?

I understand that even with a "Both" selection, fuel may not drain from both tanks equally, but you can always switch to the fuller tank for a little while then back to both in that case.


texts:
On this article about Sporting Event TFRs on the Flight Service website, they mention unpublished TFRs:

Play Ball! Be Aware of Sporting Event TFRs June 26, 2016 when you ask
the specialist for TFRs along your route of flight or request an
online briefing, you may expect the specialist to provide unpublished
TFR information that is not associated with the “blanket” sporting
event TFR. Ensure you check your route of flight for the possibility
of a Sporting Event TFR or published TFR.

What is the difference between a published and unpublished TFR?
From the article I would infer that Sporting Event TFRs are considered published, but I don't think they are published anywhere else but in the NOTAM. Appearing in a NOTAM is not considered as being published, right?
Where are the published TFRs being published now? NOTAMs used to be published in Notice to Airman Publication (NTAP). But, from these notes on the FAA website it seems that NTAP is being retired. So, where would the NOTAMS be published moving forward?


texts: Where is the 'zone of reversed commands...'?

texts:
There seems to be some confusion about where the 'zone of reversed commands' really is, i.e. where a decrease of airspeed results in an increase of drag.

Some references place that zone to the left of the minimum of the power required curve, while others place it (correctly, in my opinion) to the left of the minimum of the thrust required curve... Those minima are separated by a 30% difference in airspeed, hence the distinction isn't academic...

Two examples of these contradictory references, one taken from the internet, and the other from a book on gyros ('Flugphysik der Tragschrauber'):


texts: Why don't airliners have bigger cockpit windows?

texts:
A bigger cockpit window would increase the pilot's vision of a runway. So why can't they be bigger?

Note that this question covers cabin window size already, but this question is about cockpit windows specifically.


texts: Are aircraft with squirrel cage fans as wings viable?

texts:
I'm having trouble finding it, but a few years back I saw a YouTube video where a gentleman had designed and built an aircraft that used what I can only describe as squirrel cage fans for the upper surface of the wings. As far as I recall he made some bold claims about how efficient and capable this design was.

I was skeptical at the time and haven't seen this design since my original viewing of the video.

Does anyone know anything about this design? If so, is it viable at the scale of your average drone? Is it viable at the scale of a transport category aircraft?


texts: Where can I find regulations in different countries for flight level rules based on direction of flight?

texts:
I'm from Brazil, and here we use the West/East rule, so we use an odd flight level when we fly between 0/360 - 179, and when we fly between 180 - 359 we fly in an even flight level.

But what should you do in other countries? Where I can find those rules?

I've heard that in Europe it's totally different, and that in some countries in Asia they use meters, instead of feet.

Where can I find this information?


texts: Why was brown chosen to represent the ground side of an attitude indicator?

texts:
Is there any particular reason for having the ground represented by brown on an artificial horizon or PFD?

Blue represents sky, brown represents earth, which will be used for easily identifying the aircraft attitude (along with line of origin). Using blue to represent the sky makes conventional sense. But why is brown used? Is there any scientific reason for using brown instead of another color?


texts: Does taxiing in London City (LCY) happen on the runway?

texts:
I recently had a ride to LCY (London City). Awesome, by the way. They have only one runway (09/27) and no apparent taxiways.

(Source: Google Maps)

After landing, how do the aircraft get from the runway to the terminal? Do they just perform a U-turn on the (end of the) the runway and taxi back to the terminals?


texts: Were airworthiness certificates revoked for B737 Max?

texts:
Following up from this question - or more specifically Brian Drummond's comment on the accepted answer:

  Or even revoked without modification, if something new is discovered about the existing components (e.g. failure modes)

When B737 Max were grounded due to suspected issues with MCAS, what happened to the Certificates of Airworthiness of individual aircraft?  Technically speaking,

  something new [has been] discovered about the existing component

Per the quoted comment, this could result in the certificates being revoked.  Did it actually happen? If not, what formal measures exist that prevent somebody flying a B737 Max? (Other than common sense of course.)


texts: Does two-way communication failure include one-way communication failure?

texts: Code 7600 means lost communication, more specifically two-way communication failure. I wonder whether two-way communication failure means losing the capability of maintaining two-way communication or  not? If the pilot can only hear but not transmit, is it also included in two-way communication failure?


texts: Can two aircraft be allowed to stay on the same runway at the same time?

texts:
My understanding is that the runway should always be cleared, and occupied by no more than a single aircraft for takeoff and/or landing at any given time.

Is there any scenario in which ATC can clear two aircraft to occupy the same runway at the same time? Like clearing them to takeoff one by one: clear the front one to use part of the runway to takeoff first, and then clear the other at the threshold to takeoff.


texts: What are the most common uses of radio communication when flying?

texts: What are the most common uses of radio communication in aviation? I know that many aviators communicate with the people in towers with radio, but what do pilots say to the people in the towers and vice versa? What do pilots and ATCers communicate about.


texts: Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?

texts:
As I understood from this article, wings on an airplane basically create lift by pushing air down.

Maintaining the lift force expends energy because air needs to be continually accelerated downwards. In the "energy budget" of the airplane, this energy cost appears in the form of extra drag due to the wing, which must be compensated by extra engine thrust.

It seems to me then that the power required to keep an airplane at a constant altitude using a wing is exactly equivalent to the power that would be needed if we would "simply" use a downwards-pointing fan instead of the wing.

Now, some posts on this website compare VTOL aircraft to airliners of similar size, and state that VTOL requires much more thrust (e.g. here - I would post more links but I'm not allowed to). But according to the reasoning above, shouldn't it require exactly the same amount of power to put a plane in the air, whether using a wing or directing the engine thrust downwards?

Please disregard, for a moment, the technical difficulties and safety issues. They are discussed in other questions related to gimbal thrust and VTOL aircraft. My question has to do with energy expenditure and power.


texts: What does the actual path of air within a turbojet engine look like?

texts:
While Wikipedia describes the flow path as axial, I wonder if the path could be helical instead. Wikipedia explanation is described first in section 1, section 4 is for what could be the actual flow path, and sections 2 and 3 list the reasons for that. Section 5 is my question.

1. Usual high-level explanation

Wikipedia explains air flow in a jet engine this simplified way:

Flow path, Wikipedia, author: Jeff Dahl

Not obvious on the picture, there is a stator with vanes after each rotor, to create the pressure increase on vanes pressure side, and to straighten the flow for the next stage of the cascade, else there would be no compression and the engine would be an expensive fan. See this question for a picture showing the stators.

2. Taking into account blade and vanes

Usual depiction of the path, taking into account blades and vanes, is zigzagging, similar to:

The path above seems valid for motionless blades and vanes, ignoring blades are in rotational motion. If we dive into a bit more detailed explanation, the path would be refined like this:

Vanes pressure side is upward while blades pressure side is downward.

3. Taking into account blade rotation

With blades rotation, blades of the second stage do move while air is traveling across the first stage. While rotating, second stage blades deflect older air,  which now exits the second stage using a vane which is lower than the vane it exited the first stage (during this time air of the first stage has reached the second stage, but is deflected by an upper blade, etc):

Air path is therefore spiraled a bit, the exact amount of the helical displacement depending of the ratio between air axial speed and blades angular speed. This is not necessarily the exact vane angular spacing (or a multiple of it).

4. Seemingly more consistent depiction of air path

If this was the correct way it works, then the overall flow would rather be helical than axial, something more like this:

5. Question: How blades and vanes impact overall air path? How the air path can be better explained, taking into account blades are not fixed?

I'm looking for some details, perhaps blade/vanes geometry and airspeed, not an over-simplified view.


texts: Why are the best glide and best range airspeeds different for a C172?

texts:
According to Cessna 172 POH the speed for max range with power off, or glide speed, is 65, and achieved at the best L/D ratio.
However with power on the speed for max range will be around 75.
Why is there a difference between speeds for max range with and without power?
Edit-
Is this because with power off we are just looking for the lowest point on the drag curve, and with power on we are willing to accept the increase in drag from speed of 65 to 75 since I guess lift increases more then drag between those speeds?


texts: What could I do to a give a plane an emergency boost of power for takeoff?

texts: For some reason the pilot has to take off in an emergency or is on a runway too short or maybe they just want more places they can land and takeoff. The single engine plane is already light on fuel and cargo. Could adding Nitrous oxide or richer fuel or something like an afterburner for a piston engine work?


texts: How and when is a VFR flight plan closed when flying from the US to Canada?

texts:
I recently flew from US to Canada. As required I filed a VFR flight plan online (at 1800wxbrief.com). The flight plan was activated after I took off by contacting Flight Services at 122.2. They confirmed that the flight plan was activated.

When I landed in Canada I called 1800WXBrief to close the flight plan. But they said that the flight was closed by someone a few seconds/minutes after it was opened. As far as they were concerned the flight plan was already closed. After a few minutes the FBO guys notified me that they had received a call from NavCanada about us and upon notification of the safe arrival of the plane, NavCanada had closed the plan.

Does someone know how this process works or is supposed to work? Why do I need to call two different agencies to open/close flight plans?


texts: Do the compressors and turbine rotate at the same speed?

texts:
Since the turbine and the compressors are connected to each other via a common shaft, do they both rotate at the same speed. Because I've read that in some jet engines (single spool engines) they don't rotate at the same speed:

  Single spool jet engine. These are those jet engines who have one shaft inside them. The compressors and turbines rotate on a same shaft. The speed of compressors and turbines decreases half way down the compressor stages, that is why they can’t match the local airflow. The various turbines and compressors is forced to rotate at same speed which lead to their inefficiencies.

(quora.com)

Is this true?


texts: I do a lot of shortwave radio listening, and I often listen to MWARA air traffic radio transmissions based out of San Francisco for flights crossing the Pacific Ocean. When giving position reports the pilots always report fuel, position, and some strange names. Usually they give the strange name, and then report "NEXT --strange name here--". Some of the names I've heard are "Diallo", "Gallop", "Gitsol" (sp?). What are these?


texts: Accounting for torsional forces during wing load tests

texts:
According to this aviation.se question, wing load tests are done by placing weights on the wings (upside down).

This unfortunately only tests the wings bending loads (for cantilever wings) and the wing struts (for semi cantilevers) but not the torsional strength of the wings.

How do I load test a wing such that its torsional capacity is also tested?


texts: What are the differences in door types in a commercial airliner?

texts:
I was looking on YouTube at crew training videos. One door caught my attention for a Qantas 767. This door was completely electric and slid up and into the fuselage above, instead of out and to the side like most ones I've seen.

My question is how many different door mechanisms are there on commercial airliners and what are the benefits/disadvantages of each?


texts: How do manufacturers engineer their aircraft to deal with tail strikes?

texts:
I have been told that tail strikes on take off and landing are rare but do occur.  I think, in my mind, the tail touching the ground at all would just make the tail fall off, but it appears I was wrong.  In most of cases of tail strikes I've read about the plane is able to either continue on it's journey or can simply circle back to the field it departed from.

So I'm wondering, what do big commercial aircraft manufacturers (like Boeing and Airbus) do to keep tail strikes from turning into a major disaster?  How do they engineer the plane to survive the incident?


texts: What are these vehicles with no callsign used for?

texts:
I keep seeing these land based vehicles whenever I am looking airports on flightradar24, like in the image below:

Why do they come up on the radar? Do they have a transponder? What is the purpose of these vehicles?


texts: Why did the B-29 have so much leftward torque at take-off?

texts:
In this book, The Making of the Atomic Bomb by Richard Rhodes (p. 705), I read:

  [Paul Tibbets] eased the brakes [of Enola Gay] at 0245, the four fuel-injected Wright Cyclone engines pounding. “The B-29 has lots of torque in take-off,” he notes. “It wants to swerve off the runway to the left. The average mass-production pilot offsets torque by braking his right wheels. It's a rough ride, you lose ten miles an hour and you delay the take-off.” Nothing so rude for Tibbets. “Pilots of the 509th Group were taught to cancel torque by leading in with the left engines, advancing throttles ahead of the right engines. At eighty miles an hour, you get full rudder control, advance the right-hand engine to full power and, in a moment, you're airborne.”

I am not especially knowledgeable in aviation matters, but I believe that the torque is due to the B-29's four propellers all rotating in the same direction. Is that right? If so:

Why did this problem only arise during take-off?
Why did all propellers rotate the same way? Is this true for all propeller-driven aircraft with more than one engine? Why?
If the 509th Group's technique was so good (and apparently not especially complex), why did only they use it?


texts: Why do NOTAMs consist of code instead of plain language?

texts:
I'm currently getting thru a PPL course book and I don't understand this. Is there any purpose of sending NOTAMs in this format:

"RWY 08R/26L DUE WIP NO CENTRELINE, TDZ OR SALS LIGHTING AVBL"

instead of plain language

"For runway 08/26, due to work in progress, there is no centreline, touchdown zone or simple approach lighting available"

Why do they force pilots to learn common ICAO abbreviations when they could simply send the text message without encoding it? The same questions goes for TAFs and METARs.


texts:
This question is from CFI written exam. (6824)

“Under which condition is a forward CG most critical?”

The answer is

“Forward CG is most critical during landing. If it is too far forward, the elevators may not have enough power to get the tail down for a proper approach and flare.”

I don’t know why if CG is too forward, the elevators may be less effective. In my mind, if something has longer arm, that one becomes more effective like teeter-totter.

That would be great if someone could help me!


texts: How to find flying directions (similar to driving directions) for navigation?

texts:
Similar to driving directions, is there a service from where we can get flying directions? Let's suppose an airplane does not have a GPS and it has to rely on VORs for navigation.

I know about SkyVector. But if I create a flight plan there, it is a straight line. They also specify that this is not for navigation.


texts: What steps are needed to communicate with ATC on an A320?

texts:
In the description to this video, Captain Joe says that it took this inexperienced person 20 minutes to establish radio contact with ATC (in an A320 simulator).

This seems like an awful lot of time just to find and push the "push-to-talk" button. So, is there something more to it, like having to enter the right frequencies or something?

In the hypothetical case described in the video (passenger having to fly the plane), would it be enough to push the PTT button to establish contact with ATC, or are there other steps that need to be taken?


texts: What are the names and the function of these aircraft components?

texts: These images were taken from a Cessna 150 aircraft containing a Continental O-200 engine.


texts: What margin of error should one reasonably allow regarding aircraft performance?

texts:
This question generated a lot of discussion around amateur pilots often making the mistake of calculating aircraft performance based on perfect conditions and not allowing for a 'safety factor' (i.e. they flew with the maximum possible payload and the passengers had not been honest or accurate about their weight).

The issue, as one commentator stated is that

  That’s fine assuming EVERYTHING works out just like the book ie no errors in calculating performance, aircraft and engine in peak condition, field atmospherics, perfect short field takeoff technique, etc.

So, what would be a more sensible approach to calculating aircraft performance and what margin for error should be allowed? This applies to all calculations, payload, runway length, (passenger weight!), airspeed etc. Instinctively I would guess 10% would be fine, but I don't know what I'm talking about :)


texts: What is the difference between nautical air miles and nautical ground miles?

texts:
What is a simple way to understand the difference between the nautical air mile (NAM) and the nautical ground mile (NGM)?
How does the wind affect the net displacement of the aircraft as that is the only differentiating factor between NGM and NAM? (NAM by definition does not include the vertical displacement or the altitude gained by the aircraft.)

For further reference to mathematical formulae defining the above terms:
https://www.theairlinepilots.com/forum/viewtopic.php?t=320
From my deep dive in the quest to unravel the mystery of NAM and NGM, with inspiration from the BELOW answers I'm able to conclude with a couple of points:

NAM and NGM are same if wind is still

NAM measurement is independent of the wind and depends solely on the movement of the aircraft relative to the air around it. NGM is a dependent quantity which solely depends on the wind ie. With a Headwind component NGM is lower than NAM and vice versa for tailwind condition.

The usage of NAM was most prevalent in older flight planning systems for long range cruise before the age of FMCs which do the same thing electronically, NAM provides a database of performance of an aircraft in various phases of flight independent of the wind, to which the wind correction maybe applied to determine the practical value.


texts: Are there turbofan/turbojet analogues to a centrifugal-compressing jet engine?

texts:
Axial-compressor jet engines fall into two categories (and only two as far as I'm aware): turbofan and turbojet. I'm wondering if centrifugal-compressor jets also have such a distinction or something similar.

I cannot imagine how a big rotating fan-like object could both compress air centrifugally and bypass it out the rear, but I would not be surprised if some engineer found a clever way of doing it. And anyway, a centrifugal jet could be separated into two broad types based on something slightly different.


texts:
I was studying the Aeronautical Chart User's Guide and I came across the term 'radar minima' several times under the graphics depicting charted airports.

  Blue – Airports with an Instrument Approach Procedure and/or
  RADAR MINIMA published in the high altitude DoD Flight
  Information Publications (FLIPs)

  Green – Airports which have an approved Instrument Approach
  Procedure and/or RADAR MINIMA published in either the
  U.S. Terminal Procedures Publications (TPPs) or the DoD FLIPs

  Brown – Airports without a published Instrument Approach
  Procedure or RADAR MINIMA


texts: What are the conditions for an airfoil to be a "thin airfoil?"

texts: I know about the theory differences between regular airfoils and thin airfoils, but is there any condition for saying a given airfoil can be analyzed as if it is thin? The extreme case of infinitely thin makes sense, but I am curious if there is some cutoff dimension that determines thin or not thin.


texts: What's the exact moment were the spoilers are supposed to be deployed on a A320?

texts:
Are they deployed when the levers are pulled back to 'IDLE' or only when pulled back to 'Reverse'?

I still can't figure out, 12 years after, why flight TAM JJ3054 crashed into a gas station and a building, in São Paulo, Brazil. The investigation concluded that the captain pulled the left engine lever to reverse, but "by mistake", left the right one on 'CL'.

For those who don't remember the tragedy: 1- right reverse was pinned due to a malfunction; 2 - It was raining at the Congonhas Intl. Airport at the moment of the crash; 3 - the a320 landed on the touchdown mark on 35L runway ( about 1290 meters long); 4- Left reverse deployed but no spoilers nor hydraulic breaks engaged; 4 - Death toll: 199 souls.
To this day, they can't fully determine whether the captain left the right lever on 'CL' or the FDR displayed, erroneously, 80% of thrust on right engine, when it was supposedly on 'Reverse' position. The pedestal was found among the wreckage, twisted and melted beyond recognition.


texts: Why don’t large aircraft (larger than ~737-size) have even partial manual-reversion capability?

texts:
Essentially all large aircraft1 have flight control surfaces powered, either directly or indirectly, by hydraulic actuators, as do most medium-sized and some small aircraft.  Small- to medium-sized aircraft with hydraulically-actuated flight controls essentially always have some form of manual reversion capability, where the primary flight control surfaces (always the elevator and ailerons, and sometimes the rudder as well) are operated manually by the pilots, usually by control cables attached to the pilots’ yokes and pulling (depending on the aircraft) either on the control surfaces directly or on servo tabs which then generate aerodynamic forces which move the control surfaces.  This allows the flight control surfaces to remain operational in the event of a total failure of the aircraft’s hydraulic systems, albeit requiring the pilots to exert a (sometimes considerably) greater force on the controls to operate them.

Large aircraft, on the other hand, generally have no manual-reversion capability at all.  This is ostensibly due to the greater aerodynamic forces acting on their flight control surfaces at cruising speeds, which would require superhuman strength to completely overcome (despite the fact that, before hydraulic flight control boosting came into wide use, many, many large and fast aircraft were successfully flown with purely manual controls through the use of a number of force-reducing tricks).  However, in a no-hydraulics situation, having any manual control capability at all, even with a significantly- to considerably-reduced control authority and range of movement compared with hydraulically-boosted operation, would be an extremely-useful adjunct to throttle pitch control and steering (which – especially throttle steering – are difficult, sluggish, clunky, and only really usable for coarse altitude and flightpath adjustments).  So why don’t large aircraft have at least partial manual-reversion capability, despite even a little flight control authority being far, far better than nothing at all?

1 I'm using "large" here to mean "larger than a 737 MAX 10".


texts: Why would my electric turn coordinator suddenly stop working?

texts:
The electric Turn Coordinator in our Cardinal stopped working and we would like to understand the cause.
It simply doesn't move at all, it remain fix.
The red flag is not on, I have double checked the circuit breakers as well.
What could be the cause to that?


texts: Why Pitch Trim Up/Down & Roll Left/Right switches on yoke or control stick?

texts:
My understanding is Pitch Trim should hold current Pitch position, Roll Trim should hold roll position and Rudder Trim should hold Rudder position to relieve pilot of holding the yoke/stick or pedal continuously.

But why there is Up-Down/Left-Right (Pitch/Roll) switches on yoke or stick?

Appreciate, explanation of trim fundamental with respect to this.


texts: How do GA glass cockpit attitude indicators handle aerobatics?

texts: For example, consider you are flying the 8KCAB Super Decathlon (a fairly common acrobatic plane) that had G1000 (using the flagship Garmin glass cockpit as an example, answers for other types of GA glass are welcome) avionics fitted to it, and you were about to go off and practice your favorite aerobatic routine in the local aerobatics box.  Would you have to do anything equivalent to "caging" in order to keep the attitude indication functions of the G1000 from misbehaving during aerobatic maneuvers, or is that not an issue with the types of "glass cockpit" instrumentation used in the GA world?


texts: Was the intended purpose of the F-117 Nighthawk originally a stealth-fighter?

texts:
Based on this question, I learned that the F and A-Letters in the naming of (military) aircraft reflects what their intended purpose is.
A: Attack (Air-to-ground)
F: Fighter (Air-to-air)

their names mostly reflect what their intended purpose is rather than their actual purpose.
It is to be noted that the naming convention is followed only loosely in some cases. A good example is the F-117 Nighthawk, which is not a fighter aircraft in any sense of the word.

from aeroalias answer from this question.
The F117 isn't capable of attacking Air-Targets, it's only used as an attack aircraft. But the name of the Nighthawk is F-117 (Fighter).
Question:

Was the idea behind the Nighthawk originally a stealth-fighter
(Air-to-Air) aircraft but was later changed to a stealth-attack
aircraft? That would explain the name 'F-117'.
Are there other attack-aircraft with the F in the name?
Are there fighter-aircraft with an A in the name?


texts: Is there a general radio frequency in Class G for broadcasting intentions?

texts:
Let’s say you’re in class G and doing some aerobatics. Is there any standard frequency you might use (perhaps MULTICOM on 122.9?) to communicate your intentions?

Assume you’re not using flight following and that you’re VFR.


texts: Specific Acrylics for fabricating windscreen

texts: I've a experimental aircraft in need of a windshield due to crazing caused by fuel and cracking caused by stress. It is made of polycarbonate/Lexan and I want to replace it with acrylic because of its susceptibility to fuel and scratching. However, as there are a jillion kinds of acrylics I need recommendations of specific brands and types.


texts: How should a pilot respond verbally to being cleared for takeoff?

texts: When ATC says "cleared for takeoff", what's the correct answer from the pilot?


texts: What is the metal bit in the front of this propeller spinner?

texts: What is that grey spirally bit in front of the propeller mounted on this Shvetsov ASh-62 radial engine?


texts: Do airlines in Middle East use higher cost indexes?

texts: Cost index equals time cost divivded by fuel cost. Given that, do the airlines in Middle East generally use higher cost indexes because fuel costs are much cheaper?


texts: Can passenger weight shift cause a pitch shift in a commercial airliner?

texts: If all of the passengers of an airliner, such as an A320, all moved to the front of the plane, like this, would it have the potential to cause the same result, (i.e. a change in aircraft pitch, potentially causing an incident at low altitude)?


texts: What is the weight of the batteries on the e-Fan?

texts:
Airbus' own (early) page with technical data about the e-Fan provides some information about the batteries.

It can, for instance, be calculated that they hold approx. 19kWh of energy if you accept a somewhat simplistic calculation by multiplying number of cells (120) with capacity (40A ) and voltage (4V).

What I can't find is information about the weight of these batteries. Is this information available somewhere or can it be reasonably estimated?


texts: Why is the velocity squared in the lift equation?

texts:
Why is the velocity $v$ squared in the lift equation?
$$L=C_L\cdot\frac{1}{2}\cdot\rho\cdot v^2\cdot S$$


texts: How should I attach an aircraft model in a wind tunnel when testing wind gust/yaw stability?

texts: Where should I attach the rod to the aircraft model when simulating wind gust /weather vane effect in wind tunnel testing? At the center of gravity, behind the CG, in front of the CG...?


texts:
A high-wing aircraft is considered to be more stable in a side-slip because of the pendulum effect. How does the pendulum effect increase stability in high wing aircraft?

This question is about high-wing stability, not about comparisons between low and high-wing design also in the question that talks about pros and cons of high and low-wing design, it doesn't really explain the stability from an aerodynamic point of view.


texts: What is an air traffic controller's role in handoffs?

texts: I know they tell the pilot to tune into the new controller's frequency, but do they also have to do technical stuff? I'm trying to get a sense of how automated hand-offs are. For example, do controllers have to send flight progress strips to the next controller or is that done automatically?


texts: What was the reason for replacing the non-smoking sign with a "no electronics" sign?

texts:
When reading the following comment on question "Why do lavatories in modern planes still have ash trays?":

Andra: November 05 2014 at 16:00

  I have flown on an Embraer 195 where the no-smoking sign was replaced by a no-electronics sign

What is the reason for exchanging the non-smoking sign with a "Please Turn Off Electronic Devices" sign?
Of course Smoking is prohibited on all flights around the globe, so
the answer where the comment is, is untrue. But was this sign unnecessary
because everybody knows it's prohibited?


texts: Single engine failure in a light twin after lift-off: what to do?

texts:
In a previous question the case about if a turnback would be feasible, specifically for a single engine aircraft, has been analysed.

But given a twin-engine general aviation aircraft and a single engine failure immediately after lift-off, considering that my Pilot handbook says:

  A continued take-off is not recommended if the steady rate of climb according to "Section XX" is less than Y%.

Considering the quite dangerous setting, I would say that is quite impractical to go and check that table in such a situation.

What kind of indicators might I look for to check if it safe to continue? Should I learn by heart such table? (I am not sure this is practical either, is a quite complex table)

In case I am unsure what to do, apart from trying to climb for a while then turn around or immediately try land in front of me (granted that there is enough space), are there, generally speaking, other options?

In the accepted answer of the listed question is said that

  It's not reasonable to try it [a turnaround] without knowing what altitude is needed for it at current conditions.

is it possible to estimate this quickly inside the cockpit?


texts: Gliding: why pulling the stick back in a spiral dive would tighten the turn?

texts:
I have recently done my spiral dive recovery lesson in a glider ASK21.
The instructor taught me to level the wings first, then ease out of the dive by pulling the stick back. He said that pulling the stick back would only tighten the spiral and not help with reducing the speed.
Why is that? Should the nose not pitch up and reduce the speed?


texts: Can you help me identifying this WW1 German or Austrian airplane from my photo collection?

texts:
Can anyone help me to identify this WW1 aircraft?

It looks as though it reads Otto No. 202 on the plane.


texts: (B737s) Why is the automatic activation range of the AUTO mode in flight limited to "between idle and 5%"?

texts: This is the explanation on the Engine Start Switch in the 737 series FCOM. What might be the reason why the automatic activation range of the AUTO (or OFF) mode in flight limited to "between idle and 5%," rather than simply to "below idle" as in the CONT mode? Is there any good systemic reason for the limitation?


texts: Why do pilots disable the air-conditioning 'packs' during takeoff?

texts:
I've realized that some pilots turn the air conditioning units (also called 'packs') OFF during takeoff, like in this video:

LH456 Takeoff Video

Is there any operational reason for that?


texts: Conversion of Pilot's license from Transport canada to FAA post minor heart attack

texts: My husband got his license back in Canada but wants to move to the US, FAA is giving him a hard time in conversion. Is it even possible?


texts: What is the fastest accelerating aircraft on takeoff?

texts:
As of Feburary 2017 the Tesla Model S has the fastest 0-60mph time of any production car. With the fastest 0-60mph time recorded as 2.28 seconds.

This got me thinking, is there any aircraft that whilst on the ground can achieve a similar 0-60mph time?


texts:
My dad noticed it flying quite low today, sadly we do not have a better photo.

4-propellers and uniquely shaped tail assembly.

Plane was spotted in northern Poland, around 9.30AM, near border with Russia/Kaliningrad.


texts: What happened to the Boeing 737.X design?

texts: What happened to the B737.X design that depicted a downward nose much like the B787? It is not apparent in the B737 Max 8.


texts: Is it permissible to log an instrument approach for purposes of IFR currency in a non-IFR certified aircraft?

texts:
Assume you maintain VFR at all times and you have a qualified safety pilot on board. Can an IFR rated pilot fly practice approaches under the hood (view-limiting device) using an aircraft that is not IFR certified, and log these approaches for purposes of meeting his/her IFR currency?

Assume the aircraft has the required equipment for the approach (i.e. VOR for VOR approach, ILS for ILS, etc.).


texts: What would happen if someone covered a small hole in the fuselage of a plane with a soft body part?

texts: If I punched a hole of the size of a small coin into the fuselage of a plane, and then covered it with the palm of my hand, what would it happen to my hand?


texts: Why do aircraft piston engines consume so much oil?

texts: This question is related to single/twin piston engine aircraft. After flying in a Cessna 152 and a Piper Dakota I have noticed that they both consume a lot of oil. Oil check is an integral part of the checklist. Pilots carry extra bottles of oil in the back. Why is this so? Especially compared to car engines that are 'similar' and do not require such regular top offs?


texts: How does lowering altitude conserve energy in Solar Impulse 2?

texts:
In this article the author explains that the aircraft flies at a lower altitude to conserve energy.

  During the day, it climbs to its maximum cruising altitude of 8,500 metres to capture the most rays. To conserve energy, it works its way down to 1,500 metres in the evening, and stays there overnight.

How is this possible?


texts: What´s the logic behind the Power Curve?

texts:
Aircaft thrust is what counteracts drag, but in flight school they tought us that propeller aircraft are "power producers" and not thrust producers as jets. (That´s because the propeller needs the power of the engine to rotate and generate thrust, while a jet engine generate it by itself).
In both cases we can look at the thrust curve to get some performance information, but for props, we need to get a power curve also (get it multiplying thrust times airspeed values of the thrust curve) to get other performance features as Vy. (found where greatest excess power is).
I can´t understand the logic behind that, I mean, why does power affect airplane´s aerodynamic? Why is it important how much power does the engine has if what really makes the aicraft move forward or climb faster is thrust?


texts: Why does having a geometry-limited aircraft lead to lower VLOFs?

texts:
For this question, please have in mind these excerpts from the 14 CFR 25.107 - Takeoff speeds.

"(d) VMU is the calibrated airspeed at and above which the airplane can safely lift off the ground, and con- tinue the takeoff. VMU speeds must be selected by the applicant throughout the range of thrust-to-weight ratios to be certificated. These speeds may be established from free air data if these data are verified by ground takeoff tests."

and  VR must be:

"(iv) A speed that, if the airplane is rotated at its maximum practicable rate, will result in a VLOF of not less than —
(A) 110 percent of VMU in the all-engines-operating condition, and 105 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition; or
(B) If the VMU attitude is limited by the geometry of the airplane (i.e., tail contact with the runway), 108 percent of VMU in the all-engines-operating condition, and 104 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition."

My question is: why does having a geometry-limited aircraft lead to lower VLOFs? Is it because, since the aircraft cannot reach the angle of stall because of its limitation, the VMU for such airplanes is greater than the stall speed, and thus the maximum Lift Coefficient has not been reached and therefore it offers a higher safety margin regarding stall?


texts:
I am 17 years old and am interesting in pursuing a career as a pilot. I am not sure what I need to do first, but I do have a flight lesson this Saturday to see if I want to continue with this career plan.
To start off, what certificate should I work toward first and where should I go from there? I have read about the recreational pilot's license, as well as some other licenses, and was wondering what I should go for first.
Also, any links to study material for any exams I may need to take would be greatly appreciated! All of the information about becoming a pilot seems a bit overwhelming, so I am just looking for a place to start and a basic plan.
Thanks!


texts: What is this fighter jet at Weymouth NAS?

texts: The picture was taken at Weymouth NAS in about 1988


texts: What is that term to describe the wing motion range?

texts: What is that term naming the range of motion of the wings when on the ground (hanging/drooping) then bends upwards during flight?


texts: Could clouds on aircraft wings produce lightning?

texts: As air is accelerated over the wing, pressure drops and so does temperature, which is reduced to dew point and finally a cloud forms, which can be seen on humid days. My question is, can this cloud formed over the wing of an airplane produce lightning activity just like some other kinds of "normal clouds"?


texts: How much force does a helicopter's tail rotor counteract?

texts:
How much force does a helicopters tail rotor counteract?

What are the formulas for determining this? How much rotational torque is produced by spinning the blades?


texts: What's the red light in the left wing of a N.A. T-6 for?

texts:
There's a yearly flight show near my location, and there's always this North American T-6 (D-FUKK):

Today, I noticed that there's a single white light in the leading edge of the right wing, but a white and a red light in the left wing.

What's that red light for?


texts: What are these protruding elements from SU-27's tail?

texts: I recently saw in person SU-27 belonging to the Ukrainian Air Force. I spotted some protruding elements from its tail and I'm wondering what are they called and what do they do?


texts: Can you have an AME also sign off on your FAA BasicMed paperwork?

texts:
It seems that you should be able to have an AME sign off on your First, Second, or Third Medical and also do the BasicMed exam at the same time.

If you are older, like me, the Third Class Medical would be in effect for two years and when it expires, I can take the course to extend the Basic Med for two more years. I could exercise the privileges of the Third Class Medical (e.g. fly to Mexico) for two years and then continue to fly under the restricted privileges of BasicMed for two more years.

As far as I can tell, getting the BasicMed paperwork doesn’t invalidate the other certificates and getting a Third Class (or higher) Medical doesn’t invalidate your BasicMed.

Is anyone aware of any FAA (or AOPA, EAA, etc,) guidance on the issue?


texts: How does a PFD handle unphysically abrupt changes in the parameters it's displaying?

texts:
This question is about human factors requirements in the design of software components displaying instruments in a primary flight display. (It's not about how to implement the software.)

Let's take an airspeed indicator (ASI) as an example. In a "steam gauge" ASI, the needles add some inertia to the instrument, limiting the maximum rate of change it can display. This is OK, because the actual indicated airspeed (IAS) has a much smaller maximum rate of change in the real world.

In a "moving tape" ASI on a primary flight display (PFD), a software component receives updates of IAS and changes the display appropriately. The human readability of the instrument depends on the changes being gradual, so the numbers gradually "wind around" like a physical instrument: if the numbers abruptly jump, it's hard for the pilot to notice and understand what has happened.

In normal circumstances, an abrupt jump in IAS (or altitude, heading, or other important flight parameters) cannot occur, because there are physical limits on the rate of change. But the software component just receives a stream of values, and it's possible that an error elsewhere in the system could cause an abrupt jump.

Is there typically a requirement on this software component to smooth the instrument display or handle this possible situation? I can imagine some possible ways of dealing it:

The display component has a limit set on rate of change (guided by the physical limitations and the HF limit on how fast a change can be displayed understandably), and it has to reject out-of-range changes (presumably tied to an EFIS/ECAM message). When the changes are in range, the display is updated immediately without interpolation.
The display component has to interpolate between received values by animating, so that even abrupt changes appear to "wind" the instrument. This preserves the readability of the instrument but will introduce some latency in the displayed values.
The display component has no special requirement, and protections elsewhere in the system ensure that it never has to deal with unphysically abrupt changes.

I understand that per-component requirements are unlikely to be published by any vendor, so I'm happy to take an unsourced answer if it's backed by personal experience. Even information from an experienced glass-cockpit pilot who has seen this error state first-hand would be appreciated.


texts: What does pneumatic operated and electrically controlled means?

texts: I was going through A 320 FCOM and didn't understand this term


texts: How to find the flight paths of an airport?

texts:
How can I find the flight paths near an airport (e.g., Heathrow or Pearson) including cruising altitude, descending speed (variations)?

Specifically, I need a figure showing the height vs. speed of a plane as it's landing starting from the cruising altitude.


texts: Why wasn't the 737 MAX's landing gear lengthened enough to mount the engines under the wings, rather than in front of them?

texts:
The reason Boeing originally added the MCAS to the 737 MAX was to compensate for a slight pitch-up moment generated by the engine nacelles at very high angles of attack.  This pitch-up moment occurred because the LEAP engine used on the MAX series is larger and longer than the CFM56 used on the 737 Classic/NG, so Boeing mounted the new engines further forward and higher up to fit them on the plane; the larger, forwarder nacelles added more planform area to the front part of the aircraft, causing the MAX's center of lift at high attack angles to be slightly forwarder than on the Classic or NG, causing the MAX to pitch up slightly more at high attack angles.

However, the reason the Classic and NG have their engines mounted in front of the wing is that the 737 originally used the much slimmer JT8D engine, allowing it to use a very short landing gear to make it sit lower on the ground and ease the process of loading baggage and other cargo by hand.  When the Classics came along, Boeing decided to keep the 737-100/-200-length landing gear, which forced them to use a smaller-fan variant of the CFM56, move all the engine accessories from the bottom to the sides, and mount it in front of the wing (instead of directly below it) in order to give the new, larger engine sufficient ground clearance; with the NGs, which use a CFM56 variant that is essentially the same size as that used on the Classics (with a diameter all of one inch greater), they simply kept the same nacelle, pylon, and landing gear designs as those used on the Classics.

The MAX, in contrast, has a longer landing gear than all other 737s (handloading of baggage not really being that much of a thing anymore at most 737-served airports); given that they were giving the MAX a longer landing gear anyway, why not make it long enough to let the engines fit under the wings and finally eliminate the engine-mounting kludge inherited all the way from the 737-300?


texts: What would a "Plus Sign" marking be on aircraft fuselage?

texts:
What is the plus sign found on some aircraft bodies?

The first time I saw this sign was on a Robinson R44 helicopter. The "plus sign" was located below the right front door.


texts: What radios are airliners / large aircraft equipped with?

texts: I know that pilots have to talk to the tower over the radio, and apparently you have to tune the radio to the right tower frequency. I've also heard that in an emergency, you're supposed to "squawk 7700." Presumably you're not just making bird noises with your mouth, but some sort of radio code. Are these the same radio system? What radio communication systems are modern big jets equipped with?


texts: Do experienced pilots look at the inclinometers during flight?

texts:
I have been researching on the use of rudder during flight e.g. during turns and noticed that several novices have issues using the rudder to achieve coordinated turns.

Often, I see comments stating that the "sense" on the use of rudder will develop over time / rudder use becomes second nature sooner or later / you should turn based on seat of pants etc

Question: Do experienced pilots of single engine propeller aircraft actually look at the inclinometer or do they solely use their "senses" to make coordinated turns? If they do use their senses, does that mean that "stepping on the ball" is no longer applied when you become experienced?


texts: Why do most propeller-powered planes not have an autothrottle?

texts:
Why does every kind of propeller-powered plane lack an auto-throttle?

No single-props no twin-props, not even turboprops like the Dash-8 Q400. To be honest, I don't know many turboprops, but if the Dash-8 doesn't have one, why shouldn't others? I mean, even a mini Cherokee 180 has an autopilot, whats so hard implementing an auto-throttle? And the Dash-8 is an airliner... without auto-throttle!

Thanks for your answers, I would really appreciate your answers.


texts: Can (part of) the fuel in your tanks be considered "property carried for compensation or hire"?

texts:
This question brings up that an experimental category aircraft cannot carry "persons or property for compensation or hire".  However, this raises a question regarding civil-registry refueling tankers (such as the venerable N707MQ).

Since the tanker is carrying fuel on behalf of another entity (the military unit they're contracted by to pass gas to) for compensation (contract payments), wouldn't the fuel that has been offloaded on-station be considered "property", backing N707MQ and its experimental (market survey) airworthiness certificate into a proverbial corner?

(Yes -- I know that contract tankers are considered Public Use aircraft when on-mission, which probably renders 91.319 moot, but it could easily be the case that a contract could say "operate IAW FARs with the exception of refueling operations", which'd inadvertently loop 91.319 back into the situtation.)


texts: Why were the cabin lights turned on during the flight?

texts: I was on a flight last night that the Captain came on and said in three minutes we all had to be in seats and buckled due to severe storms we had to fly through. After about five minutes and until we landed-approximately 20 minutes the interior lights were turned on.  This has never happened on a flight I have been on. Was it so we could not see what was going on outside?  There was tons of lightning and clouds.


texts: How do fighter pilots manage food, drink & toilet?

texts:
There doesn't seem to be any place to bring food or drink.
And what about WC?

And for single seat combat planes?


texts: How to calculate the DC-4 landing distance with this graph?

texts:
Can someone give me a clear explanation on how to calculate the landing distance of the Douglas DC-4 with the following graph? And why is the Temperature variable not in the graph, because temperature also has an influence on the LDR?
Thanks in advance.


texts: How do you repair a grounded aircraft at a remote location?

texts: If a large passenger airliner needs repair at a remote airport without services, are there "flying repairshops" that can swoop in and do the work on site?


texts: Why is the 737’s aileron/spoiler authority reduced at low flap settings?

texts:
According to the NTSB report on the crash of United Airlines Flight 585, the ability of the 737’s lateral controls (ailerons and flight spoilers) to counteract the rolling forces produced by (say) a rudder hardover is considerably worse at lower flap settings, such that, in some cases, a hardover occurring with the airplane’s flaps fully extended might produce only minor control difficulties, whereas the same malfunction occurring with the flaps at (say) the ten-degree setting would result in a loss of directional control (pages 60-61 of the report; pages 78-79 of the PDF file of the report):

...Flap position and airspeed are important when determining controllability during a rudder hardover condition. With the rudder at about 25 degrees airplane nose right (ANR), the following conditions would exist at 150 to 160 knots calibrated airspeed (KCAS). Bank angles are noted as left or right wing down (LWD, RWD) and provide constant heading trim solution (no turns), except for the last case.
Rudder Angle …… Flaps …… Side Slip Angle …… Wheel Angle …… Bank Angle
25 ANR …………… 40 ……… 14 ANR ……………… 35 LWD ……… 18 LWD
25 ANR …………… 30 ……… 15 ANR ……………… 44 LWD ……… 17 LWD
25 ANR …………… 25 ……… 15 ANR ……………… 68 LWD ……… 16 LWD
23 ANR* ………… 15 ……… 17 ANR ……………… 107 LWD ……… 23 LWD
21 ANR* ………… 10 ……… 16 ANR ……………… 107 LWD ……… 19 LWD
25 ANR** ………… 10 ……… 13 ANR ……………… 107 LWD ……… 40 RWD
* Less than full rudder allowed to maintain directional control.
** Loss of directional control.
At 10 and 15 degrees of flap setting, heading cannot be maintained with full rudder deflection. If full right rudder is achieved with a 10-degree flap setting, for example, heading control is lost and, according to Boeing, a steady 40-degree right-wing-down trim solution is attained that results in turning flight to the right even with full left wheel deflection...

Why, for a given airspeed, do the 737’s lateral controls become increasingly ineffective as the flaps are retracted?


texts: Are aircraft pilots required to fly runway heading for a certain distance?

texts:
If an aircraft rotates off the runway relatively quickly (runway mid-point for example), do pilots need to continue on the runway heading for a minimum distance before turning based on departure procedures? For example, for the Runways 31L/R CANARSIE climb at JFK, the established departure procedure is "Climbing left turn direct CRI VOR/DM". For this same procedure, can the departing aircraft proceed direct to CRI VOR/DM like the image below, if safely possible, or do they need to maintain runway heading till the runway is cleared?
Thanks!


texts: What do Turnaround Supervisors do before departure?

texts: Before the plane is able to take off, what calculations do Turnaround Supervisors have to do and what do they have to check before the plane departs?


texts: What is this in the primary flight Display?

texts: What is this in the primary flight Display ?


texts: Are jet engines designed in a way to make an explosion result in the least damage possible?

texts: I know most engines are super reliable today, but do manufacturers do anything to at least make an explosion result in the least damage possible?


texts: What exactly is the meaning of "detent" in aviation?

texts:
I come across it in many different situations e.g. "settings changed to flight detent" or "landing altitude changes at first detent". There are other scenarios which I came across in the past, but I don't remember them.

Could someone explain me all the different scenarios and what it really means?


texts: When to switch from ground to tower frequencies at controlled airports in the US?

texts: I have heard that you can switch to the tower frequency once you are at the runway hold line and are ready for takeoff without getting permission from ground control to switch frequencies.  Is this always true or does the procedure vary for different airports?


texts: Why was the DC-8-70 successful, but not the 707-700?

texts:
The first high-bypass turbofan small enough to use on a narrowbody jetliner was the GE/SNECMA CFM56, which entered service in the late 1970s as an upgrade engine for the KC-135 tanker; Boeing almost immediately began working on a CFM56-powered 707 (the 707 and KC-135 are very close siblings), the 707-700, with a prototype flying in 1979.  Boeing offered the 707-700 for sale in 1979 and 1980 (the last 707 version in their product catalog), but got not a single order, and the prototype 707-700 was eventually converted back to a 707-320C and fobbed off on the Moroccan Air Force.

In contrast, when a CFM56-powered version of the DC-8 became available in 1982 (the DC-8-70), the airlines jumped in with both feet, even though the DC-8 had been out of production for a decade (unlike the 707, which was produced all the way up until 1979, and would have lasted longer still had the 707-700 caught on), and would thus be, except for the engines, years behind where the 707-700 would have been.

Why did the CFM56 fare so much better on the DC-8 than on the 707?


texts: Is there a tank priority sequence for using the fuel tanks?

texts: Is there a tank priority sequence for using the fuel tanks, or does the pilot decide?


texts: How do seaplanes do run-up checks without brakes?

texts:
Usually on run-up you want to check the response of the motor when changing for example the carb-heat (if existent). At least we did so on my intro flight (yey!). To prevent us from rolling onto the active runway we (obviously) held the brakes.

Now I wondered how pilots of floating planes and flying boats prevent movement on pre-takeoff checks. Additionally most images I found from flying boats they usually have more than one engine. Similar question here: How do pilots prevent swimming circles as one engine is started and the other(s) is/are not?

I scanned this FAA document from this related question but that is mostly is about landing (which is interesting as well but I assume that as in the linked question the airframe and especially the water resistance take care of that).


texts: What is the difference in performance between variable pitch prop and two fixed propellers for take-off and cruise speeds?

texts:
Push-pull configuration aircrafts usually feature identical engines and propellers working only in tandem for multiple reasons like higher speed, better climb rate, reliability, cost, ease of maintenance, etc.

It may sound unpractical for piston engines were saving fuel will not outweigh the downside of one engine being a dead weight but may be a good idea for lighter electric or a combo, where engines may also be optimized for different propellers.

Can it be possibly beneficial to have tractor prop for take-off:

blown lift
no FOD risk
less noise outside

and pusher specifically optimized for cruising:

larger diameter as no ground clearance issue
no parasite drag
more stability
less noise in cabin

Benefits to consider:

efficiency
higher achievable speed
higher altitude
still two motors for redundancy

Problems:

Stowing nose prop.
Foldable prop should be cheaper than VP.

Less take-off power.
Electric motor for tractor could drive 4-bladed prop at peak power.


texts: Why are planes allowed to fly with just one pilot?

texts:
I chanced on this article which raises the titled question: Why aren't two pilots mandated for all planes esp. military? What happens if the lone pilot becomes incapacitated, esp. if the plane has passengers who aren't pilots?

Two captains of Cathay Pacific Airways lost sight during two separate flights, according to the Hong Kong Civil Aviation Department. In both cases, the first officer managed to land the aircraft safely.
[...]
On January 28, 2016, a pilot of the British Royal Air Force had lost sight during a training flight in a Hawk jet in North Yorkshire. Another jet had been scrambled with an instructor on board that helped the impaired pilot to land at RAF Leeming air base. Sources quoted by the Telegraph had said at the time that his vision was affected by the sudden deterioration of an eye infection.


texts: How does the 3 pin ground power connector (AN2551) work?

texts:
I understand the premise of the 3rd (smaller) pin (top of the image) is to delay switching power until the two main pins have made positive contact with the aircraft socket on plug insertion; and similarly, to disconnect power before the two main pins lose contact on plug removal.

This setup is desirable as it;

ensures correct polarity as the plug only fits into the socket one way
avoids arcing on insertion and removal which in turn;

removes a potential source of ignition (especially if refuelling)
prevents damage to the socket and pins

My understanding is that all pins on the plug are always live and that all control logic and switching is part of the aircraft's electrical system. ie: the switching occurs internal to the aircraft between the ground power socket and the main bus via a relay (powered by the external power source) that is ambiguously referred to as the external power relay (referring to its function, not its location).

I have several questions;

If the plug pins are always live, why does the third pin not present a potential arcing risk? (I assume the lower power has something to do with this but you can get a reasonable spark from a 9V battery).
How is the power on the 3rd pin limited?
Why not use the 3rd pin to switch the power at the source so that the positive pin is only ever live when connected?
eg: short the 3rd pin to the ground pin on the aircraft socket to activate an external relay (part of the power supply - not to be confused with the relay in the aircraft referred to as the external power relay) to switch the power on/off before it even reaches the aircraft. As a bonus this would also  (slightly) simplify the aircraft electrical system.
Is all the control logic always in the aircraft?
Is any aircraft power required? ie: will this work if the aircraft battery is completely dead?
Is the aircraft battery required to be physically connected (to complete the circuit for the relay)?

Sources that got me this far:

https://www.askmehelpdesk.com/aviation/3-pin-ground-power-unit-connector-aircraft-375477.html
http://aircraftplugs.com/download/i/mark_dl/u/4008094775/4627385351/purpose_of_third_positive_terminal.pdf
https://www.industrial-electronics.com/images/aircraft_8-9.jpg


texts: What flight conditions trigger the "altitude, altitude" callout on an A-10?

texts:
I saw this video that shows an A-10 mission in Afghanistan. At 4:31 and 6:08 the callout "Altitude, altitude" is audible.

I would like to know which flight conditions are required to trigger the callout.


texts:
Wikipedia article tells that supercruise is a condition when an aircraft can achieve velocities above Mach one without using the highly inefficient afterburners. But still, there are not a lot of engines which can achieve this.

What is the specific requirement for an engine to achieve supercruise? Why can't most of the engines reach supercruise without reheats enabled?


texts: On a flight with short stops, do you terminate flight following at each stop?

texts: On a cross-country trip, is it normal to terminate FF at each stop and reacquire it (potentially just a few minutes later) for the next leg, or would ATC prefer that you advise them it'll be a short stop and maybe let you keep the code to reduce their hassle later?


texts: Are there any specific weight or structural reasons to choose low vs. high wings for a cargo aircraft?

texts: I have a large cargo aircraft concept and I am debating between a high or low wing.  It seems like both are viable, but intuitively it seems structurally harder to support a high wing.  Alternatively though I like the idea of a high wing to raise the engines and provide better field landing abilities.  Can anyone comment on the weight penalties associated with one concept or the other?  Is there a structural advantage to one configuration?


texts: How does latitude affect the air temperature at 8 km altitude where planes fly?

texts:
Is the air temperature (at 8km) above the North or South poles colder than the same altitude above the equator?  Why?

Ground level air temperature difference between coldest and warmest places on Earth can be >70C. As you get higher, the temperature drops, of course. Does it mean that near Arctic circle air temperature at let's say, 8km altitude still maintains approximately the same difference with the 8km altitude above equator as at the ground level? Or does it even out? Is it perhaps even possible to have air at some altitude significantly warmer than at ground level?