texts: Do major passenger airline jets have airbrakes/speedbrakes?

texts:
Now I've heard that passenger airliners do not generally have airbrakes , and simply use their spoilers as airbrakes since they can perform the same function.

Are there any major jets that use speedbrakes (by major I mean widely used by countries or airlines, and it must be a passenger jet)


texts: Is there an online source for Canadian Instrument Approach Procedures?

texts: The FAA offers instrument approach procedures on their website free of charge, and EASA does too.  Does Canada have them online for us to use?


texts: How to properly compute the stable vertical path load factor

texts:
I've been told by someone else that in a stable flight when the vertical path of the aircraft is maintained, the Nz value is equal to cos(pitch)/cos(bank), but I can't seem to figure out how that is derived, the only place on the whole internet where I was able to find that info was here: Inside another stack exchange post, however, it didn't explain how was the formula derived. I do understand that inside a banked turn with 0 disturbance to the vertical path the aircraft's load factor is defined by 1/cos(bank) as explained in the textbook I read: Introduction to Aerospace Engineering with a Flight Test Perspective.
But this doesn't explain the cos(pitch) part of the formula, and nowhere was I able to find anything related to it on the internet. Can someone please explain this to me? Thanks!


texts: suppose, i assume Aerodynamic Center lies at Center of gravity.  Then apparently moment by lift will be zero about CoG. But in reality Centre of Pressure may be behind aerodynamic center and still be producing a moment. So isn’t using aerodynamic center absurd?


texts: What is this intake at the back of a 737?

texts:
I've circled an intake in red on the images below. I am working on a 737 NG and I don't know what it's for. I am thinking it's a pressure probe for APU control but I am not sure.

Source

Front view: comparing location to aft door confirms it's the same "device." (Full image.)


texts: Can a stopway withstand thrust of B737 engines on takeoff if the aircraft is lined up on the edge of the runway?

texts: Can the thrust of Boeing 737-300 engines break the asphalt surface of a stopway marked with yellow chevrons? Can anyone give a documented reference?


texts: What are the limitations of the aerodynamics modelling used in flight simulators?

texts:
I've asked around, and it seems all flight training programs use a combination of flight simulators and aircraft flights to train pilots. This works well for most pilots who fly airliners which don't spend much time in turbulent air or close to obstacles, and the flight simulator aerodynamics are very close to what is experienced in actual flight.

My question is where do the flight simulator aerodynamics models breakdown? I was wondering this in relation to rough air flying skills, where the aircraft or helicopter flow field interacts with surrounding environment (like inside a convective storm or near obstacles like trees and buildings) I would imagine these are situations that are hard to model since it depends on accurately modelling the interactions, which are difficult to run quickly enough for running a flight simulator. Fixing this by only doing flight training seems dangerous, especially for newbie pilots since the margin for error is very slim.

Personally, even though its more expensive than a flight simulator, a first person view drone would be a good intermediate step between the flight simulator and full scale training, with the response characteristics and control interface being the same as the full scale aircraft or helicopter.

That said, I don't know where the flight simulator aerodynamics begin to diverge from what is actually is experienced in real life, so the drone might be completely unnecessary. I'd love to see how this problem is resolved now.


texts: What fixed wing, and motor, plane or jet, has the largest range between its minimum and its maximum airspeed by which it can safely fly for prolonged periods?


texts: Are there countries where not all plane crashes are investigated (even if deadly)?

texts:
background information
I was struck by the news of this deadly plane crash on 20 Dec 2018 which claimed 8 lives and apparently is not investigated as the plane and its potential survivors were not even searched for:

A Gomair Antonov AN-26 on behalf Central Electoral National
Independent Commission (CENI), registration 9S-AGB performing a cargo
flight from Tshikapa to Kinshasa Ndjili (DR Congo) with 7 or 8 crew
and election materials, was cleared to descend to 5000 feet on
approach to Ndjili's runway 06 when the aircraft went missing about
20nm short of Kinshasa's runway 06 at about 10:00L (09:00Z). The
aircraft was found about 24 hours later in hilly terrain (peaks rising
up to 700 meters/2300 feet MSL) about 19nm before runway 06. Local
Congolese media report Authorities did not launch a search for the
aircraft. The aircraft was found by random chance by a local, who
reported 8 bodies in the wreckage. (source)

question
Aren't countries bound at least (if nothing else) by international treaties and ICAO regulations to

perform SAR operations for missing aircraft lost in their sovereign airspace
and investigate the cause of the accident ?

In which countries can deadly plane crashes lack either one or both ?

scope
Q (from a comment below): "There are countries which may not have the resources to conduct their own investigation of a crash and may request assistance from another country."
A: Good point. Countries unequipped to handle S&R or crash investigations can voluntarily outsource either one or both to other countries. For the pupose of this question, a crash in country X investigated by country X or Y does equally count as being investigated, so this is NOT what my question is about. I'm asking about dead passengers searched for by NOBODY and crashes investigated by NOBODY.


texts: How do planes know what altitude they're cruising at?

texts: I know that when planes enter the aerodome containing the airfield of destination, the ATIS will tell them an altimeter setting so the system knows how to calculate their altitude above their field; what about in cruise? Do they listen to the ATIS of every sector while cruising as well?


texts: What is the difference between a forward, aft, high and low center of gravity?

texts:
I would like to know the difference between when the center of gravity (CoG) is forward and aft? And high and low?

I already know that the lower the CoG, the greater the static lateral stability. A forward CoG is generally more stable than an aft CoG. So does this mean that a low CoG is the same as an aft CoG?

Note: If the effects of an AFT CG is not the same as Low CG, then what's the effect of each one of them or what's the difference between them?, and most importantly when is the CG is AFT or Forward?, and when is the CG Low or High?


texts: How can I identify airliner types that don't have ACARS?

texts: Is there a way to identify what commercial airliners are still flying without ACARS today? Most modern commercial airliners are equipped, but I know some 737s still fly without ACARS, for example.


texts: What is the purpose of this item next to the cockpit window on the B737?

texts: Hello does anybody know what the purpose of this odd looking shape is


texts: Did Boeing need MCAS because the 737 MAX didn’t meet FAA longitudinal stability requirements, or was it to make the MAX feel like the NG?

texts:
I’m confused on this. I’ve read in multiple different places that

  MCAS was required due to the easier stick forces at a high angle of attack and a high G force, and because of this, the Max didn’t meet FAA longitudinal stability

Others have said that

  The Max has MCAS because they wanted it to feel like the NG

Confirming the easier forces, but excluding the FAA longitudinal stability possibility. Almost every source contradicts another one, and I’m unable to locate any info through the FAA site.


texts: Why does Airbus not display the exact airspeed on the PFD?

texts:
On every other PFD (I know), the exact airspeed is displayed as big number on the PFD. To clarify what I mean, here are two pictures:

Source, added square, Boeing PFD

Source, added square, D10A EFIS

Now, when we take a look at the Airbus PFD, we can see that there is no exact speed display:

Source, added square, Airbus PFD

This is one of the biggest differences between the Airbus PFD and other PFDs. What led Airbus to this unusual decision? Is it maybe because Airbus pilots don't need to watch airspeed as close as other pilots, because of the numerous flight envelope protection systems and the fact that the autothrottle controls the speed until 20 feet above ground?

Is there just no need to know the exact airspeed and Airbus wanted to remove a source of distraction?

Is it possible to turn an exact speed display on if the pilot wants or needs it?


texts: What is this aircraft with pipes at the flight deck windows?

texts:
This image comes from a site about aircraft tractors:

What could be the reasons for this old aircraft to have pipes at the flight deck windows and to be moved near a forest?


texts:
I heard once that fighter jet cabins are NOT pressurized, but the pilot's suit is, which prevents problems with decompression if the cabin gets shot.

But a military fighter pilot much later told me that the cabin is, in fact, pressurized and that getting shot (the cabin) and the resulting decompression are not that much of a bother, at all.


texts: Why can APU supply both bleed air and electrical power up to 10.000 feet but bleed air alone up to 17000?

texts:
I am reading my company's FCOM and I saw there the following information.

APU Bleed + Electrical Load: Max Alt 10000 ft.

APU Bleed: Max Alt 17000 ft.

APU Electrical Load: Max Alt 41000 ft.

If APU can supply bleed air up to 17000 ft, why supplying electrical load at the same time is not possible?

Does bleed air usage on the APU affect the generation of electrical power?

Thank you all for your answers.


texts: What is the correct phraseology for "runway 03 R”?

texts:
What phraseology is normally used for "runway 03 R" by air-traffic control and pilots?

A couple of possible options I came up with:

runway zero three R
runway three R
runway zero three right
runway three right

Is there any standard or preference of one form or the other to reduce confusion during communication?


texts: What happens to a plane that goes to / from an enclave when the surrounding country closes its airspace?

texts:
When Pakistan closed its airspace, planes that had routes flying over Pakistan had to deviate around that country.

What would happen to planes en route to or from Lesotho, if South Africa closed its airspace?

Are the planes simply unable to leave or enter the country, or there is a law / regulation about this situation?


texts: How should simulator time be logged in a pilot logbook?

texts:
In a full motion Level C or D simulator like those used by the airlines and for jet type ratings:

How should a pilot log the simulator time in their logbook?  I.e. Can you log:

Total Time
Instrument Time
Time in Type
Cross Country Time
Night Time
Landings (including night landings)
Dual given/received
Anything else?


texts: Who has the responsibility to make altimeter corrections in cold temperatures?

texts:
I work as air traffic controller in Asia and we refer to both ICAO and FAA regulations. As winter is coming, there is a debate on altitude correction (or altimeter correction?) for cold temperatures. Some insist that we (ATC) don't have the responsibility to make altitude correction, and the others insist that we have, when ATC performs radar vectoring. (We know that the pilots have responsibility when IAP.)

In related to this, ICAO DOC 8168 states (Vol 1, Chap 4 Altimeter correction):

  The pilot is responsible for these corrections, except when under radar vectoring. In that case, the radar controller issues clearances such that the prescribed obstacle clearance will exist at all times, taking the cold temperature correction into account.

So, I've tried to find references about this but failed.

Here're my questions.

1) Is there a document or manual for ATC about how to make altitude corrections when radar vectoring?

2) Why is there no altitude correction for hot temperatures that make for a steep angle of descent?

3) Should ATC-issued altitudes take into account temperature-induced altimeter error, or does should ATC issue the true altitude and leave the responsibility on the pilot for making the correction?


texts: Why then don't aircraft fly even higher, for even greater efficiency?

texts:
After reading various superb QA on here I now see that (basically) aircraft are more efficient per passenger-mile, at higher altitudes.

Why don't we go even higher, than current typical airliner cruising altitudes?

What's the deal?

If there's an efficiency transition, have we reached it?


texts: How does a self-centering rudder affect left-turning tendency?

texts:
In this answer to a question about controls, Peter Kämpf mentions the Klemm 35:

  ...the rudder has two narrow strips which are deflected slightly to the left and the right, respectively. This increases the force gradient over deflection for the first few degrees when the rudder is moved away from its centered position.

How does this interact with left-turning tendency coming from the engine slipstream? Normally, small movements of the rudder are needed to counteract the effect of the slipstream on the fin, so increasing the force required for small movements would seem to hinder rather than help the pilot.

On the other hand, I'd expect the right-pointing strip to be in the lee of the fin (as the slipstream passes left-to-right over it), which would reduce the force on it, letting the rudder move a little to the right on its own, which is exactly what you want.

What actually happens? Does the neutral position of the rudder change at different power settings when flying straight and level? Does this arrangement reduce your foot workload compared to other aircraft?


texts: Why are all-moving horizontal stabilizers common but all-moving rudders rare on fighters?

texts:
According to Wikipedia

  Stabilators were developed to achieve adequate pitch control in supersonic flight, and are almost universal on modern military combat aircraft. All non-delta-winged supersonic aircraft use stabilators because with conventional control surfaces, shock waves can form past the elevator hinge, causing severe Mach tuck.

If this is the case with supersonic pitch control, why use an all-moving elevator but a conventional rudder? Doesn't yaw control have the same issue? Or is it because rudders are rarely used?


texts: Do ETOPS rated airplanes ALWAYS fly with ETOPS requirements?

texts:
So, as this is kind of a confusing subject I want to make sure I get a real answer, that's why I ended up doing it here. As ETOPS rated airplanes need to fly with certain rules so they comply with all the requirments, I am having kind of a hard time understanding if ETOPS rated airplanes need to comply with , for example, fuel requirements in a short flight that doesn't actually need ETOPS procedures. Example:
An A330 ETOPS rated aircraft is making a short flight from KPDX to KSFO, does it have to carry the extra fuel for ETOPS requierments, departing and landing with the extra weight and reducing performance?


texts: How are Rolls-Royce engines different to others?

texts:
I heard that Rolls-Royce engines has 3 engine spools.
Are they different in design compared with GE, PW engines?

thanks


texts: Does an AME's advertisement on the back of the medical certificate affect the document's validity under the FAA?

texts:
I know a guy who has a medical certificate from an AME based in Dallas Fort Worth, and the front side of the paper has a side-by-side printing of the front and reverse of the FAA medical certificate (FAA form 8500-9) and the back side of the physical paper containing the front and reverse on one side has the AME's website, name and phone number with an airplane graphic.
In short, the back of the paper is a doctor's advertisement.  I have heard rumor that a local DPE says this would make the medical certificate invalid.
Does anyone know of a regulation, LOI, etc. that would confirm or deny this stance on the medical's validity.  Apparently, this AME is quite popular, so if this is true, then that would mean that many pilots currently hold an invalid medical certificate.
I personally find this hard to believe.


texts: What is the drag of helicopter rotor at jet speed?

texts:
I wonder if a jet plane can have helicopter rotor for vertical take off and then, when moving forward just stops that rotor and uses lift from wings like normal plane.

Since rotor blade seems thinner and smaller than wings, I guess when turned off, its drag should be much lower than wing.

So why doesn't that type of hybrid plane exist?

Or the drag of the rotor at the jet speed would be so high? If the drag is high, why is it high, since the rotor blade is also airfoil like wing?


texts: What is pendulous suspension in magnetic compass?

texts: I am not able to understand what is pendulous suspension and how centre of gravity and centre of suspension are related in magnets and their errors. Can someone explain this in layman language or could share the link which gives good 3d animation of the same.


texts: What is this yellow section around the cockpit window?

texts:
Saw this while boarding the flight the other day, travelling between HYD (Hyderabad, India) to CCU (Calcutta, India) on Indigo Airlines. Aircraft was an Airbus A320.

There was a yellow patch around the window. Was this because the same was repaired?


texts:
Some larger airports in the US use land-and-hold-short (LAHSO) operations, meaning you're cleared to land, but only if you're able to do so without going beyond specific point (usually an intersecting runway) on the roll-out.

What if you're forced to go around just before touch-down, perhaps even with the mains hitting the pavement, you will inevitably head straight for, and cross, that intersecting runway. Would there be a risk of colliding with aircraft operating on the intersecting runway?


texts:
Wikipedia list a number of runway pavement. For specific airports, the choice is obvious (e.g. ice, snow). But there are few pavement I cannot figure out how to decide which one use.

Why an airport would choose asphalt over concrete or bitumeous asphalt for the runway pavement? What are the reason for the choice?


texts: What does Airspace 24 mean in this chart supplement?

texts:
I found this line in Leesburg Executive Airport (KJYO)'s chart supplement:

I have looked in the Chart Supplement Legend under section 29 and there is no information about such an airspace. At the bottom of the legend it says to look at AIM's Chapter 3 for more details, but none can be found there. I googled this to no avail.
I am guessing that whatever it is might have something to do with KJYO's situation. It is located in the DC SFRA and has an FDC NOTAM "Leesburg Maneuvering Area" which lists required procedures when operating in and out of the airport. Don't know how "24" comes from all that, though.


texts:
I am wondering whether or not it is possible for an air plane to fly through a rainbow, and, if so, does anyone have any pictures or experiences of what you can see?

I've always been intrigued by this.


texts: What advantage does Kawasaki C-2 have with a twin-engine configuration as compared to its competitors like An-70 or A-400?

texts:
While reading about various military transports, I came across the specs of Kawasaki C-2 and a few questions popped up. So please bear with me here if I list them all together as points, I hope someone here will help me understand more by answering this.

1) What advantage does the C-2's get with a twin-engine setup when compared to the 4 engine set up in most of its competitors (A-400, An 70/188) which have similar MTOW's?

2) The next question is related to C-2's MTOW & payload - with a 145tn MTOW the An 70/188 has a max payload of 47tn but with a 141tn MTOW the max payload of C-2 is a full 10tn less at 37tn. Also, considering that the dimensions are very close to each other what is the reason for such a huge difference?

3) Next is again payload & thrust related - the max thrust generated by C-2's twin engines is at 532 kN (266 x 2) its close to the 468-568 kN (117 or 142 x 4) of the IL76MD-90A and higher than the 468-500 kN (117 or 125 x 4) listed for the Y-20, but both these platforms list a much higher payload capability (~50-66 tn max.) while I understand that the MTOW of the other two are much higher which gives them much higher fuel load and range, shouldn't the similar thrust mean it can carry similar payloads even if it is for a shorter range? Can someone explain to me why such a huge divergence?

4) Lastly is a bit general, I couldn't find the max fuel capacity of the C-2 from any open sources or articles, so, if someone could answer that and share any interesting things they know about C-2 that would be great.


texts: Why do my ears pop if the cabin is pressurized?

texts:
Simple question:

If a commercial airline cabin is pressurized, why do my ears pop as we ascend and descend? I was always told this was due to a change in pressure, but if the cabin and my body are at the same pressure, there should be no force causing my ears to pop.


texts: How do altimeters cope with varying lapse rate?

texts:
How do barometric altimeters measure altitude above atmosphere datum if the laps rate of the pressure is not uniform, not constant? Imagine these lines representing pressure lapse rate:

560hpa
570hpa
580hpa
600hpa
700hpa
800hpa
1000hpa sea level

And so on. Now imagine your plane flying through these numbers vertically, and in your kollsman windows you set the datum line 1000 so, when you get lower (in numbers) the altimeter will read higher. Now when you’re passing trough the 500hpa pressure lines you can see the lapse rate is decreasing even if your climb rate is constant. My question is, does the altimeter misread your true altitude? Does the altimeter “think” it’s lower than what it is in reality, due to lapse rate?


texts: Is it possible to calculating sea-level pressure with an unknown base station altitude?

texts:
I'm trying to program a BMP180 pressure/temperature sensor to calculate altitude.  The method I've seen used is to input your current base station altitude to calculate the sea-level pressure.  It seems a little tedious to input the base station altitude everytime, so I was wondering if it is possible to calculate sea-level pressure without a known base station pressure.

I've been trying to calculate sea-level pressure through iteration.  I would set the default sea-level pressure at 1013.25 mb, use this number to calculate an estimated altitude, use the estimated altitude as my current base-station altitude to calculate a new sea-level pressure, use this new number to calculate an estimated altitude, etc...  However, I noticed that my results are diverging.  Is there a better way to calculate the sea-level pressure?


texts: Does the FAA have risk targets for specific activities?

texts:
Does the FAA have or publish goal values for various risks?

I'm looking for something that says (e. g.) "We rate passenger airline flights as 'safe' if there are fewer than X casualties per million flying hours" or the like.  Even better would be some kind of matrix reflecting "safe", "of concern", "hazardous", "dangerous", etc.


texts: What is the longest time after which plane crash survivors were rescued?

texts:
I found:

Aviator Bob Gauchie retains the record for solo arctic survival by a downed airman, enduring 58 days of arctic weather before his rescue in Canada 1967.
After 72 days on the glacier, 16 of the 45 people on board the crashed Uruguayan Air Force Flight 571 were rescued alive.

Any longer ?

scope: For the purpose of this question only the initial rescue from the crash site shall be considered.


texts: How do flight attendants know seat belts are fastened?

texts:
I'm a simple curious traveller. I always see flight attendants passing by the seats checking whether belts are fastened. They pass quickly and without looking carefully at each single person, to see if the seat belt is fastened.

I stared at them and found them looking at some specific point on the ground that could possibly tell them with a glance, but I couldn't figure out what was that point.

Can somebody explain how do they check the seat belts status?


texts: What equipment does an A320 need in order to operate under RNP 2?

texts: What are the aircraft equipment/systems eligibility requirements for Airbus A320 airplanes to operate in RNP 2 airspace?


texts: What aircraft has a single constant orange light?

texts:
I live under a fly path in Oldham near Manchester and I see planes passing by every day/night as they approach the airport. However today around 21.20 I have seen something different too.

A plane just passed above our house to start its approach to Manchester then when it was further away roughly above Ashton-under-Lyne I noticed a contrast single orange light passing above the house.

It was somewhat higher than the passenger planes around this area and it's travelled with constant great speed. I followed with my eyes until it's disappeared on the horizon above the peak district (took about 1.5-2 minutes). It's travelled in a direction about SSE (roughly towards London). I couldn't find anything on the Internet suggesting anything flying with constant orange light. BTW it had no sound whatsoever and it wasn't showing up on flight radar either as I checked that straight away. I do not drink and do not smoke funny things. Any idea what this could be?


texts: Do you need FAA approval to land a helicopter on Miami Beach?

texts: Do you need FAA approval to land a helicopter on Miami Beach, Florida?


texts: I 've found out this great website where you can get historical AWOS weather data. I would like to use it for a commercial application but I don't find any data license. Do you know if the AWOS data are free to use for commercial purposes? Can you point me to a relevant link?


texts: GA Headsets - is there a standard for the replaceable microphone?

texts:
I've noticed that on many (but not all) different types of GA headset, the microphone seems to be somewhat modular, with two holes at the end for the microphone boom to insert into, and two screws at the front that seem to be able to be used to both hold it in place on the boom, and also fasten the two parts of the plastic microphone assembly in place.

Example microphone modules:

Is there some standard for microphone modules, or is what I'm noticing just coincidence?

Background: One of my headset microphones no longer works due to being ... unintentionally regurgitated upon - I'm wondering whether I can just buy one that looks similar.


texts: Is there a site that tracks all flights?

texts:
Some of my flights are tracked on sites like Flightradar24 and others are not, regardless of flight plans being opened and closed. It would be nice to go to a website that tracks all flights, so I can review the flight dynamics after I land.

I am interested in a website that provides this service, not an app (I have had limited success with these).


texts: In an F-18, how do rudders deflect during cross winds and gusts? Can rudders be deflected by different angles?

texts: Deflection of rudders can balance moment about the centre of gravity. I have thought of non-symmetric deflection of rudders so that net sideward force is create to balance the moment about the center of gravity of the aircraft.


texts: What is the difference between stopbars and Intermediate Holding Position Lights?

texts: I know that stop bars continuously light red and stand at before taxi route joint, holding points, or at the runway entrance, but what about the Intermediate Holding Position Lights? How can we differentiate between the  stop bar and Intermediate Holding Position Lights with regard to function and location or color? I added pictures below; I am sure of the stop bar, but am I correct about the Intermediate Holding Position Lights? Btw; there is a definition for Intermediate Holding Position Lights: A set of three amber lights or full red stop bar are provided at intermediate taxiway holding positions.


texts: Can you be a monocular airline pilot in Europe?

texts:
I know this question has been asked before but it was for the US and I would like to know about Europe.

I was born with no vision in my left eye, and I have always wanted to become a commercial airline pilot, I have very good vision in my right eye. I just want to know if I could do it in Europe and if I would have any restrictions on my medical like not being able to fly internationally or fly big planes like the a380, and if it’s possible to become a captain. Or if it’s possible to get it without a soda, and would there be any differences. Or can you get a soda in Europe like the us.


texts: What are these silver stripes on Cosmic Girl for?

texts:
Cosmic Girl (a 747-400 used for launching things into space)1 has a network of silver-coloured stripes on its empennage, starting at the (closed-off) last cabin window, and going aftward and upward from there, with branches running onto, and up, the vertical tail; there also appears to be a similar stripe emanating from the (also-closed-off) third cabin window behind the second main-deck exit door and running downward onto the wing root:

(Image originally by Crishazzard at Wikimedia Commons; modified by me.)

What are these stripes for?

1: It actually had that name before it became a rocket launcher - it didn’t get it from Virgin Orbit.


texts: Is there a light civilian helicopter capable of a 250 NM trip without refueling?

texts:
Is there any light civilian (GA) helicopter that's capable of making a 250 NM trip with required fuel reserves? I'm thinking of something smaller and lighter that a private individual might buy. (I'm thinking about something that costs less than USD 150K, if that helps to explain the type/size of helicopter I'm asking about.)

The Robinson R22 and RotorWay A600 look like they wouldn't make it without a refueling stop, and I haven't found any extended range STCs for these either.

Does anyone know if such a helicopter exists?


texts: Why at increasing BPR the efflux area should be enlarged (at high BPR)?

texts:
I am working on a university project. I have to comment on this chart (that represents efflux area variation with the variation of the BPR).

Every other engine data are kept unchanged (turbine entry temperature, flight altitude, flight speed, compression ratios ...)

$ BPR \le 7 $

It is clear that at low BPR the area of the nozzle should be enlarged in order to let the flow through at sonic conditions.

$ BPR \ge 7 $

What I can't explain is the reason why at high BPR the area of the nozzle useful for "swallowing" the propellant flow should be enlarged.

My explanation (is it right?)

I think that this is due to the constant (approximately) slope of velocity decrease at nozzle exit and the progressive slower decrease of the flow.

Is this the reason or there are some other explanation?


texts: How do planes respond aerodynamically when bringing them into inverted flight by rolling?

texts:
For the sake of the question the plane is fully capable of inverted
flight, no problems with engines etc.

Background of the question is the observation that the airflow around
the wing must also invert the direction. If I look from the end of the right wing in direction of the fuselage, I see the air moving around the wing counterclockwise, while inverted it must spin clockwise. So at one point the relative air flow must cease completely on average, there is no difference anymore between top and bottom of the wing.

While the airflow is not turbulent, this should feel for the pilot like stalling because there is no lift, also the wingtip vortices should stop. The "no lift" position should be somewhere near the point when the plane has its wings vertical.

So once a pilot brings a plane into a roll, what exactly happens? Is it a smooth transition from full lift to no lift to full lift back or is there a sudden loss of lift which must be overcome by spin inertia? I have also the suspicion that trying a roll with a too high angle of attack risks a real stall because the restart of the circulation around the wing is hampered.


texts: What are the spikes on Ingenuity's blades?

texts:
I am puzzled by the spikes on Ingenuity's blades (marked by a red box in the image below).

What is their function ?
Are these special to Ingenuity?
Why don't they collide during high RPM?
Don't they induce unwanted drag and/or turbulence?

I have tried searching NASA's website but couldn't get a description of these particular featuers. Answer to any part is appreciated.


texts: What is the difference between AHRS and ADIRS?

texts: Whats is the difference between Attitude and Heading Reference System and Air Data Inertial Reference System ?


texts: Why does the A330 sit nose-down on the ground?

texts:
The passenger versions of the A330 have a small but noticeable nose-down angle when sitting on the ground:

(Image by contri at Flickr, via russavia at Wikimedia Commons.)

In contrast, A330s built as freighters have a noticeable bump under the nose,1 which allows the nose gear to be mounted low enough down that it reaches the ground with the aircraft sitting level:

(Image originally by Ceecookie at Wikipedia, via Leptictidium at Wikimedia Commons; cropped and modified by me.)

I can think of some disadvantages of having a nose-down body angle on the ground:

Boarding (and, to a lesser extent, deboarding) would be slowed down slightly by the passengers having to negotiate a sloped cabin floor (especially those having to drag very heavy pieces of luggage uphill in the process).
Ground servicing of cabin equipment would be expected to be made somewhat trickier by the sloped floor (a galley cart or other rollable object inadvertently left unattended for a moment would roll away towards the cockpit, potentially causing damage or injury if it has a sufficient length of unobstructed aisle to get up to a good clip).
The nose-down body angle tilts the aircraft forwards compared to the situation that would arise with a completely-level fuselage; this moves the aircraft's center of mass forwards, shifting more weight to the nose gear that would otherwise be carried by the main gear, and, thus:

Requiring a heavier, more substantial nose gear than would otherwise be the case.
Reducing the maximum braking force available from the main gear (and thereby increasing the aircraft's stopping distance).
Slightly decreasing the aircraft's directional stability on the ground (ye olde wheelbarrowe effect).

Indeed, the vast majority of large airliners sit level on the ground, rather than nose-down, so why is the A330 different in this regard?

1: Freighter A330s converted from passenger aircraft have no such bump, as the aircraft's cargo-loading system is fully capable of dealing with the slight slope.


texts: Does night takeoff and landing currency also count for daytime currency?

texts: My initial thought is that night currency satisfies daytime currency, but what gives me pause is FAR 61.57(a)(2) notes that a non-current pilot is allowed to conduct day VFR or day IFR flights without passengers to obtain currency.  There is no mention of night flight being allowed.  This seems to imply that day flights are required for daytime currency.


texts:
What kind of dihedral would be most stable?

An airplane with wing span x ft and whose dihedral begins from the root(attachment point to the fuselage) of the wings and whose wing tips are y ft above ground level.
An airplane with wing span x ft and its dihedral begins from the mid point of the wings from the wing root and its wing tips are y ft above ground level.
An airplane with wing span x ft and its dihedral begins at a distance 2/3 of each wing from the wing root and its wing tips are y ft above ground level.

Note: They are all low wing airplanes of equal size, power, weight, wing span, wing chord etc. Only the starting point of the dihedral and the angle of dihedral  vary.

I also believe a polyhedral wing will be most stable(everything being equal). Am I right?


texts: What would reasonably take to get current to fly general aviation aircraft after many years

texts:
What would it take to become current? I was a fairly proficient pilot and accumulated around 5000 hours. In 1984, I changed careers and haven't flown since. I was licensed for commercial and instrument operation of airplanes (single and multi-engine). I had an instrument rating and AGI, IGI, CFIA, CFII and I even  got an ATP certificate (although no type ratings and at 74 years old, I don't think that would be usable). I also have an airframe and power plant mechanic certificate.
For 16 years I lived and breathed aviation. I couldn't make a reasonable living at it so I went back to school and switched to computer science. I am  now retired, still in reasonably good health and I am considering getting back into aviation as a hobby.
I know the rules have changed. Airspace categories are different and airplanes have become incredibly more expensive (holy cow). And the avionics make the stuff I was using look like they should be in a museum.
My question is, "What would it take to make me legal to fly?" Could I ever be a safe pilot again?


texts: Is the number of private pilots increasing or decreasing?

texts:
My interest into aviation grows by every day and I seriously start thinking about working in the industry later, as I am very interested into avionics and pilot supporting devices in the general aviation field.

However, what's the trend in general aviation at the moment? Is the number of PPL stagnating, rising or even decreasing. It would be nice if you have data about Europe, the US and International.


texts: What airfoil is used on the Lazair ultralight?

texts: This is the airfoil of the famous Lazair ultralight. What is the name of this airfoil?


texts: How does it feel like to be outside a flying airplane?

texts:
Riding a motorcycle on a freeway at over 200 kph you surely feel the rush of air around you. A typical commercial jet airliner travels at approximately 3-5 times that speed at cruise altitude. Assuming you could open the cabin door closest to the wing fuselage and step out on to the wing, does the air rush feel more 3-5 times more intense than if you were on your bike? Does it mean there is more air resistance to blow you off if your bike could travel that speed? If so, then what would be required to secure yourself to the aircraft in order not to be blown off from the air velocity around you, again assuming that air temperature and thickness of air to support human consciousness isn't a factor?
Then there is a issue of cabin depressurizing, but again assuming this is ignored or resolved through pressure equalization with the outside pressure (oxygen masks will need to be worn by the rest of passengers inside for survival)


texts: Why is there still an Air Berlin branded plane operating as of Sep 5th, 2018?

texts:
Yesterday, I flew from TXL and was quite surprised to see this during taxi:

It very much looks like people boarding an Air Berlin flight, an airline that supposedly does not exist any more. Local time was 12:20pm.
What happened here? Did some subsidiary survive the bankruptcy? Did someone buy the brand rights? Did they just not find the time to rebrand all the sold planes (in almost a year)?

Edit:

Since requested in comments: I do have another shot further to the right. Zooming in seems to reveal that the registration number is D-ABKM (or D-ABKW?)


texts: Where can I find real-time flight tracking with the least amount of delay?

texts:
I am an aviation fan, relatively new to the industry.  While I thoroughly enjoy plane spotting at my local KORD airport, at times I tune to LiveATC and Flightaware to get my fix.

Unfortunately, my observations are that flightaware is a bit delayed 3-5 minutes, and not all air traffic is shown.

I tried Flightradar24, it is more current, but wildly inaccurate at times and a bit "synthetic" as they try to fill in the data gaps.

Aside from getting into an actual ATC tower, which I am sure is nearly impossible for a civilian, what are my best options as far as getting my fix in?  Apps, services, etc (paid and free), doesn't matter.


texts: Definition of "Rotation Speed" vs "Lift Off Speed" vs "Fly Off Speed"

texts:
Is rotation speed and lift-off speed ever used interchangeably? (AMENDED Question) Is lift off speed and fly off speed the same? (See supplemental info below)

I thought I clearly understood the difference between these two terms:

Rotation is the point at which the longitudinal axis of the aircraft is "rotated" about its lateral axis from a horizontal orientation in order to increase the angle of attack of the wing.
Lift-off is the moment when the aircraft is no longer in contact with the surface (i.e. ground or water).

However, I was reading something the other day where the two terms appeared to be used interchangeably, which I accepted at first, but now its bothering me. It was a POH and it said that for normal take-off rotate at 70-75 KIAS. However, the POH also says that the "Normal takeoff distance in Section 5 is based on lift off at 65 KIAS."

Found it, here is the text:

So to get the Normal takeoff performance, you can't use normal takeoff procedure?

By the way, after further reading of the POH, I don't think the "lift off at 65 KIAS" is a typo. See the maximum performance takeoff which says to rotate ASAP and "fly off" at 61 KIAS the single engine stall speed of the aircraft. (See Copy Below).

I think they were just hard-core back then. So this raises another terminology question "fly off" speed. So we have rotation speed, lift off speed, and fly off speed. My interpretation is that for max performance takeoff rotate ASAP, if airplane flies below 61 KIAS, then keep it in ground effect until 61 KIAS, then fly off.


texts: How should this Bendix course deviation indicator from the '50s be read?

texts:
This is a Swissair photo from a DC-7C panel.

Source

I have seen photos on airliners.net of these in DC-6s, VC-118 and Constellations. It appears that other companies besides Bendix made these indicators, but they are similar in appearance and function.

I've searched unsuccessfully for patents, or any other information that would describe what I am asking about:

What are these "45" scales for?
What is the flag in the window used to indicate?
What are these two lines for?
What happens when the test button is pressed, e.g., the loc, glideslope needles move to some position, #5 rotates to some position, #2 flag appears?
What does this "airplane" indicate?


texts:
With reference to this article on aviation herald at Accident: Shanghai B738 at Shanghai on Jan 3rd 2020, tail strike on landing, captain and first officer swapped seats in flight where the report discusses swapping seats between captain and first officer. I'm trying to figure out why so much weight was given to swapping the seats - except may be bad timing.

As a person who is not affiliated with aviation, I am curious to know apart from responsibilities and prestige that goes with the position, are there any differences between flying from right hand side vs left hand side. Does captain side has more controls available?

If someone gets incapacitated for whatever reasons, how is it managed?

Additional question - as pilots move up the career, do they have to learn few skills again like controls they used to perform with left hand vs right hand as they swap the seat.


texts: How to make use of linear acceleration and gyroscope data?

texts:
This is strictly not aviation related so please feel free to move it to the correct section.

I have a 9 axis IMU, which gives me yaw, pitch, roll, magnetics, gyros, accels etc.

I currently make use of the roll, pitch and yaw (true) however I want to learn how to use the rest of the data. I know that the raw magnetometer data can be used to judge when the true yaw is not accurate enough and even correct it. I'm reading up more on that subject at the moment.

However what I can't find much resources on is on how to make use of linear acceleration and angular acceleration. I have successfully converted the data from raw units to g/s.

How do I obtain the acceleration of my craft with the data?


texts: Is it best to use a thick airfoil or an undercambered airfoil for slow speed flight?

texts:
The more the thickness,the more the frontal resistance,hence the more the drag a thick airfoil will produce.
Under cambered can help increase lift without increasing the airfoil thickness , therefore not creating as much increase in resistance or drag . ..which is more plausible for a slow ultralight,a thick airfoil or an under cambered airfoil?

Source: https://www.flitetest.com/articles/beginner-series-basic-aerodynamics


texts: What is this plane spotted from Outer Banks, NC?

texts: What is this plane spotted from Outer Banks, North Carolina?


texts: what are the Common roll angle and roll rate limits for civil flights?

texts:
I'm currently doing simulations for eVTOL type of vehicles and for the purpose of controlling the attitude, I'd like to know the common limits for roll and roll rates (more important) that are in place for civil flights. I'm interested both for airplanes and helicopters even though I do prefer information for rotary vehicles.

I've spent a few hours already searching through the web but for some reason, I'm not able to find literal values in documents such as ICAO annexes etc.
So it would be really helpful for me to know at least the approximate values. I appreciate any answer in advance. Thanks

UPDATE with respect to comments:
I am interested in upper boundary, i.e. what rate should not the vehicle exceed. I imagine that there is some at least recommendation that aircraft of a particular type should not exceed this rate, otherwise the passengers can spill their coffee, get sick etc. So it could be also partially dependent on the current wind situation, gusts and so on.

In terms of particular regulatory office, it doesn't really matter as this information should just give some overview of possible values because right now I really dont have any clue.


texts: Am I correctly calculating the density altitude?

texts:
I came across the following question while studying for the FAA PPL written test:

Determine the density altitude for these conditions:
Altimeter setting: 30.35
Runway temperature: +25°F
Airport elevation: 3,894 ft. MSL

I performed the following steps:
Temperature (°C) $\color{red}{= 5/9 × 25} = 14 $
Pressure altitude (PA) $= 3,894 + (29.92-30.35) × 930 = 3494 $
Density altitude (DA) $= \text{PA} + 120(14 - 15 + .002×\text{PA}) = 4200 $
Yet that answer is not listed, and according to the DA/PA graph provided, DA is 2000ft.
My final formula seems to be correct according to Wikipedia, plus it also matches my intuition of how PA works: According to the question we have 14°C at 4000ft, as opposed to the expected 7°C at 4000ft; seeing as temperature is higher, DA should be higher than PA.
Where am I going wrong?


texts: What other circumstances may cause the autopilot to trip out?

texts:
I recently watched Air Crash Investigation, Air France Flight 447.

The autopilot handed back control to the flight deck after the pitot tubes temporarily froze. The autopilot knew it was getting naff information and said: "We can't deal with faulty information so we are handing control back to the flight crew".

This got me thinking. What other instances, beside instrument error, if any, will the autopilot trip out, and hand control back to the crew?

An initial Google search was not helpful I am afraid. A pdf of the Airbus systems (350 pages long) was available, and a news source on everything the autopilot does, but nothing mentioning examples where all of a sudden the autopilot may switch off, even temporarily.

The reason I ask this is that if this is the only reason the autopilot may trip out, surely the crew of Flight 447 would have been aware that it was due to information that was not correct, and therefore to just remain as they were until the sensors came back to life again.

That is what I can not understand.


texts: What are (wing area)/(weight) ratio in birds and airplanes?

texts:
I like to know the usual ratio of wing area over weight in birds and airplanes?

I mean if total weight of an airplane is 100 Lbs(Kg), how much should be the least total area of it's wings?

And also like to know this ratio in birds, if there are information about?

I need this ratio to estimate the wings size, if I want to create an aircraft to lift different weights(it's weight + load weight).

For example, if a person with 150 Lbs wants to fly, how much should be the least area of his wings?


texts: Can I buy a A320 FCOM, FCTM and QRG as non-pilot?

texts:
I am very interested in the Airbus Systems. I really like the FCOM of the A320, there are some of them on the internet.

However, I like holding physical books in my hands more, than reading them on a screen. But I don't have the paper nor the print color to print more than 1000 pages.

I would really like to buy a FCOM of the Airbus A320-Family. Can non-pilots, like me, buy a FCOM? If yes, where?


texts: Can one purchase a Cessna 182JT-A although it has not yet been certified?

texts:
To the best of my knowledge, Cessna's 182JT-A has not yet been certified. At least I couldn't find on Google any indication that it has. Lots of items that certification is "imminent" but no real facts.

Yet, I see them for sale and YouTube has videos of them flying. Am I correct in believing that it is possible to buy one and then operate it as an experimental aircraft?


texts: Book recommendations for learning how to fly?

texts:
With the success of this question, which asks about good books on aerodynamics, I thought I'd ask another general question regarding books that we can turn into a community wiki.

What are good books to use to learn how to fly?  And yes, I know that, in the end, you'll just need a good instructor.  But there are several books that suppliment a good instructor, or can be used by people who are interested in learning to fly, but perhaps are unable to get an instructor just yet.

Note: I am well aware this is a very general question.  But I would like to have a centralized resource, vetted by users of this stack, that we can point to when someone asks for text resources on learning how to fly.


texts: Do TSA regulations allow CFIs to start training non-citizens before the TSA has approved their training request?

texts:
49 CFR 1552.3 says (emphasis mine):

(4) TSA has informed the flight school that the candidate does not
pose a threat to aviation or national security, or more than 30 days
have elapsed since TSA received all of the information specified in
paragraph (a)(2) of this section.

This one implies we can't train until we hear back from the TSA for aircraft that are in "Category 1—Regular processing for flight training on aircraft more than 12,500 pounds".
However, the section on "Category 3—Flight training on aircraft 12,500 pounds or less" says:

(4) The flight school begins the candidate's flight training within
180 days of the date the candidate submitted the information required
under paragraph (a)(2) of this section to TSA.

So that tells me that as long as the information is submitted, we can begin training a non citizen immediately (for less 180 days).  What is the point of this?  Where is the security?  Is this correct? Or is it just another confusing regulation?
What is the current industry practice? Do CFIs provide the training in this situation? Or are more TSA checks initiated?


texts: Why do the engines on a 737 have a flattened lower surface?

texts:
Inspired by this answer.

The engines on a 737 are not perfectly circular when viewed from the front. The bottom of them are flattened a bit.

Why is that? Is it for aerodynamic or ground clearance reasons?


texts: What is the efficiency of running an electric motor from a gas generator?

texts:
If you were to run an electric motor from a gasoline or diesel generator, how big would the generator have to be to run something like the Siemens electric engine? Is this a viable model for replacing a heavy piston engine or is it too inefficient?

The link below says standard portable generators are capable of 6.13 kWh per gallon of gas.

The Siemens only weighs 50kg and delivers a continuous output of 260kw. Does that mean I'd need a generator 42.4 times as powerful than most portable generators and be burning a gallon of gas a minute?

I know a lot of small aircraft engines weigh around 150kg and several use gear boxes as well.

So Does this mean you could save the weight to make the plane electric but not battery powered or is the generator simply going to be too inefficient?

https://www.google.com/amp/s/settysoutham.wordpress.com/2010/05/26/portable-generators-about-half-as-efficient-as-power-plants/amp/


texts: Can any military aircraft (only fighter jets not the military cargo ones) be stopped using Arresting Gear technique?

texts: I know in mostly all of the seaborne landings on the Naval warships is done using Arresting Gear and there are some land based airfields also which used arrested gear methodology but do any aircraft specifically military ones (just the fighter jets)can be stopped using this or there is something specific feature in an aircraft which makes it Arresting gear compatible?


texts: Do glider pilots require normal headsets?

texts:
When flying light aircraft, we use headsets which include ear protection from the noise of the fan. Being that unpowered gliders are presumably much quieter, are the same headsets used?

My assumption is that gliders are radio equipped, and pilots are still talking to ATC or their airfield traffic information. If this is not the case, are headsets still used for intra-cockpit communications or are they really quiet enough to talk normally?


texts: How is spilled fuel cleaned up at airports?

texts: In an accident where an airplane leaks fuel onto the ground, how is it cleaned up?


texts:
Air Force One is obviously a big deal.  We close terminals and implement other seemingly crazy safeguards against terrorist attacks while the president is en-route to an airport.

How does ATC protect the president whilst in the air?

I have heard of TFRs for "VIP in the area" reasons — is that for AF1?
I am guessing that the aircraft identification is blocked, but wouldn't they still need to have the transponder on for TCAS?

Specifically, the Wikipedia page on Air Force One has the following quote:

  Air traffic controllers gave Air Force One an ominous warning that a passenger jet was close to Air Force One and was unresponsive to calls. "As we got over Gainesville, Fla., we got the word from Jacksonville Center. They said, 'Air Force One you have traffic behind you and basically above you that is descending into you, we are not in contact with them – they have shut their responder off.' And at that time it kind of led us to believe maybe someone was coming into us in Sarasota, they saw us take off, they just stayed high and are following us at this point. We had no idea what the capabilities of the terrorists were at that point."

Does having the transponder on just paint a huge target on the radar for terrorists?


texts: What’s the setting range altimeters can handle? Is there a standard requiring a certain range for aircraft to be certified? Are there many occasions where a QNH is so high or low that airplanes have problems handling that?


texts: Why did FAA regulations initially prevent passengers from making phone calls during a flight?

texts: For many years, the FAA prevented people from making phone calls during a flight. Was this because a phone call interfered with aircraft communications?


texts:
What is the name of the maximum altitude at which a helicopter can fly?

I recall it as "vertical limit", but I can't find a Wikipedia page for it other than a movie of the same title, which seems to concern mountain climbing altitudes.


texts: Which engine is more efficient between turboprop vs jet?

texts:
Are turboprops really more efficient than jets?

If yes, does that mean that airlines who use jets sacrifice fuel for faster flights?


texts: What happens if a private pilot's license isn't used for some time?

texts:
I have a question about the currency of a Private Pilot's License: if someone obtains a PPL but doesn't fly for a period of time, is there a time after which some conditions or restrictions are imposed?

I'm mainly interested in Europe and the US.


texts: What is the maximum altitude a skydiving plane can fly?

texts:
Is there a standard maximum altitude which skydiving planes can fly?

I am mainly asking about the sports activity, not military parachuting.


texts:
Pulsejets are mostly known for propelling the V-1 flying bomb, and have some use as small remote-controlled plane engines. In either case, the pulsejets aren't particularly big, as far as jet engines go.

How big can a puslejet be realistically made? Assuming that, for some reason, there was a need to power a much bigger plane with pulsejets, at which point would it stop making sense to make the pulsejet bigger, and use multiple smaller pulsejets?


texts: Why does linear airfoil theory break down at hypersonic speeds?

texts: Why can't we just extend linear supersonic theory beyond M = 5? I've looked at NASA papers discussing everything from geometric effects, air disassociation, and thermal coupling, but no clear and concise explanation as to why we can't just extend linear airfoil theory beyond M = 5.


texts: Is it possible to give an endorsement via text message or email?

texts:
Is it possible to give an endorsement to student pilot via email or text message?
For example, I gave an endorsement to my student for a XC. However, he stuck at the destination airport after the weather gets bad. On the next day, the weather became good enough to come back. But, he needs another XC endorsement to fly solo.

How can he receive an endorsement to come back?
Is it possible to send an endorsement via text message or email?
Is it okay to receive an endorsement from somebody CFI at the destination airport? (Let's say they don't know each other.)

That would be great if someone could help me!


texts: What are the laws on photographing aircraft in Australia?

texts: Are there any types of aircraft that I am forbidden from photographing aircraft. (Australian aircraft, primarily) in Australia? Are there regulations on what I do with the photographs I take? I assume there is some sort of thing published by the government but I couldn't find any.


texts: Why are many jet aircraft designed to cruise around FL350-370?

texts:
If the flight distance permits, the B737-800 will cruise at FL350, the A320 a little bit higher...

Flying at FL370. Photo: Live from the Flight Deck by GolfCharlie232 (reframed)

Elements such as time to reach cruise altitude, engine and airframe efficiency at this altitude, and acceptable cabin pressure surely influence the choice, but:

What are exactly the important criteria used, and the compromises made by engineers?
Would engineers choose other altitudes if the technology or any other current limits could be improved?


texts: How come nobody survived Air Moorea 1121, yet other people have survived crashes from altitudes more than 90x higher?

texts: Air Moorea 1121 crashed from no more than 400 feet, yet people have survived far more awful disasters, such as UA232 or JAL123.


texts: Could a civilian aircraft in distress land in Area 51?

texts: Just curiosity, but in case of a real life-threatening emergency (where you can't fly to closest airport or strip), would they (Air Force, military or whoever) allow the plane to land on the Area 51 airstrip? Have there been any occurrences that we know of?


texts: Statistics - Does the majority of new pilot training occur at controlled or uncontrolled airports?

texts:
Is there any data available on where pilots undertake their training?

I'm interested to know whether most (USA) pilots complete their training at a controlled airport, or at a uncontrolled field.

I'm interested in this because it would likely give an indication of the relative level of comfort of new pilots operating in both controlled and uncontrolled airport environments.

I assume that it's likely that a Designated Pilot Examiner would be more likely to operate out of a controlled field just due to traffic volume, so the location of issuance of a pilot's certificate isn't necessarily a good proxy for where training hours are undertaken.


texts: Does the airflow from a propeller over a wing contribute to lift?

texts:
How I understand it, the perfect propeller would move air rearward at the exact same velocity as the free stream, i.e. the propeller air will merge with the free stream and have no real influence on the flow-field over the wing.

However a non-ideal propeller (thus all real propellers) accelerates the air to a higher speed than the free-stream and thus alters the flow-field over the wing.

My question is: Does this airflow from the propeller increase the lift generated by the wing?

My question obviously assumes that the propeller and wing is in the same plane and that the air from the propeller thus hits the wing.


texts: Is "V/n" geometric or effective pitch in advance ratio formula?

texts:
V   is the freestream fluid velocity, typically the true airspeed of the aircraft or the water speed of the vessel
n   is the rotational speed of the propeller in revolutions per unit of time
D   is the propeller's diameter
Why in my aerodynamic book from aeronautics  university write  V/n in advance ratio formula  is aerodynamic /"effective" pitch(I agree with that), but some members which are aerodynamics experts at this site said that this is geometric pitch(zero slip)?
example


texts: Are some countries' civil aviation authorities safer than others?

texts:
Okay, put down the pitchforks, I'm not pointing fingers at anyone!

I'm just aware that every country has its own civil aviation authority, and I wonder if there's any reason to believe that some countries perhaps have safer standards, and perhaps are more vigilant in enforcing them.  As opposed to, say...the opposite of that.

My assumption is that most countries, if not all, take aviation safety extremely seriously.  And that, as a result, aviation accidents are truly random occurrences that have nothing to do with the country of origin for the flight.

But I may be wrong, hence I'm asking.

NOTE:  I am not interested in opinion and personal experience on this.  If you don't have statistics and accident reports to back up what you are saying, please refrain from answering.


texts: How should I deal with a passenger experiencing hypoxia over the Grand Canyon?

texts:
I am taking my mom for a trip over the grand canyon. My mom lives at sea level, whereas I live at 5000ft, and workout at 8000ft daily.

The VFR lowest route over the Grand Canyon is 11,500ft MSL. If I am flying over this with my mother and she starts to exhibit signs of hypoxia, what are my options?

It is the law to remain at the prescribed altitudes and headings while flying around the Grand Canyon. That being said, obviously passenger safety comes before anything else. If my mom gets sick, I would have to drop in altitude, but what kind of consequences would I face for this?

In the event of hypoxia in one of these corridors, what would be the best way to deviate while remaining safe and courteous?


texts: Is this the relationship between rpm and thrust of a Turbofan?

texts:
In this graph from the FAA Airplane Handbook Chapter 15, page 5:

It looks like it is talking about "jet engines" but is it engine type specific or it is for both turbojet/fan/prop/shaft? It looks right about the more rpm the engine is running, the more thrust it would produce, but is the relationship shown here for jet engine or piston engine?


texts: What are interesting cases of ATC agreements between countries?

texts: I'm doing some research about cooperative documents between nations regarding ATC; does anybody can mention interesting cases of agreements across the globe? Relations such as Swiss/Others and Hong Kong/China (during British domain) comes to my mind. Also, is there known, famous cases of events (incidents/accidents) caused by disagreement between ATC of different countries you could mention?


texts: Why do jet engine igniters require huge voltages?

texts:
Wikipedia's Components of Jet Engines has this to say on the igniters:

A high voltage spark is used to ignite the gases. The voltage is stored up from a low voltage (usually 28 V DC) supply provided by the aircraft batteries. It builds up to the right value in the ignition exciters (similar to automotive ignition coils) and is then released as a high energy spark. ...

Most modern ignition systems provide enough energy (20–40 kV) to be a lethal hazard should a person be in contact with the electrical lead when the system is activated, so team communication is vital when working on these systems.

I bolded that part I'm interested in. 20 to 40 kV? That is a huge, huge amount of voltage. Why on Earth would a jet engine need that much voltage to produce a spark? I thought kerosene was relatively easy to ignite.


texts: What is the correct crew procedure for an unreliable airspeed alert?

texts:
When the crew receives "airspeed disagree" message on the primary flight displays, they may face some hazardous situation.
Is there any procedure, using a table containing pitch, power, altitude and weight, to avoid stall, for example?


texts: What requirements are needed to fly an approach that requires you to fly over the US/Mexico border?

texts: I was flying North of El Paso Texas listening to El Paso Approach when I heard Approach ask a Falcon Jet if they could fly into Mexico to fly a Runway 4 GPS approach.  At El Paso, the runway 4 approaches require you to fly across the US/Mexico border into Mexico.  What requirements are needed to fly an instrument approach that requires you to fly over Mexico?  Would you require a radio telephone permit to use the radio even though you are talking to an FAA controller?


texts: What are the differences between Lycoming and Continental engine designs?

texts:
Inspired by a discussion in chat.

Most GA piston singles are powered by either Lycoming or Continental engines.
The engine designs used by both manufacturers are broadly similar (4-cycle, horizontally-opposed, gasoline-powered, air-cooled), and they're both generally available with either carburetors or fuel injection, but I know they're not "identical products".

What are some of the differences between the designs used by the two manufacturers, and what practical implications do those choices have for pilots?


texts: Couldn't airplanes have more emergency exits?

texts: Being near an emergency exit improves considerably the survival chances after an accident. Why not put one exit at every 5 rows?


texts: How can the flap deflect to higher angles (than the wing) without experiencing loss of lift?

texts:
For a simple aircraft wing, assume the stall angle of attack of this wing is 16 degrees. Now, if I use the same airfoil as used in the wing for the flaps, I am able to deflect the flap at quite greater angles. How is that possible? If I want to CFD analyze the flap geometry separately, can I use the maximum deflection of the flap as the angle of attack of incoming air in a CFD analysis? [Meaning will the CFD results obtained by isolating the flaps from the wings and conducting the analysis at an angle of attack the same as the maximum possible deflection of the flap, will be the same as when I conduct the analysis of the flaps together with the wing]?
How can I determine the maximum deflection of the flap? How to choose the best flap configuration for an aircraft? How determine the maximum possible deflection for the ailerons as well?


texts: Do horizontal stabiliser force direction change with CG variation for a given aircraft?

texts: I am wondering about the direction in which horizontal stabilizer provide force. I know that it can provide either upforce or downforce. But I am wondering whether is it determined for a particular airplane, I mean it is established for example that B737 tail will provide only a downforce and CG limits are set up in a way that when correctly loaded the tailplane will provide every single time a downforce or it depends from the CG location that tailplane will have to provide either a downforce or an upforce?


texts: How small can turbojet engines be made whilst remaining fuel efficient, light, cheap, and producing enough thrust to carry a human, gas, and casing?

texts:
I've seen many videos of small turbojet engines (small enough to hold in your hands) that produce 30-40 pounds of force. If you mounted a couple of these on a small craft, that wouldn't even support human + gas, and especially wouldn't support a fuselage or any other casing.

What size is efficient with gas but still produces a lot more than 40 pounds of thrust?

An extra question you don't need to answer: what is an effective way of tuning fin direction on the exhaust end of one of these engines? Basically, how can I twist a knob and make the fins tighten or twist in a direction I want the thrust to move in?


texts: How do I calculate the aircraft's deviation from track in this exam question?

texts:
I’ll have my PPL exam soon. I asked my instructor at the school about this question and even he doesn’t know the answer. I’ll appreciate your help.

  Question 22

  Flight from point A to point B. NDB is point B.

  magnetic track (MKK)=245°
  magnetic variation (“delta” m)=5° W
  magnetic compass swing ( “delta” k)=3° E

  When 30 km inbound to point B, your QDM-225° What is aircraft
  deviation from track?

  Right of track 10km(5.4 nm) (Nk=+10km)
  Left of track 10 km (5.4 nm) (Nk=-10km)
  Right of track 6km(3.2 nm) (Nk=+6km)
  Right of track 12,55km(6.7nm) (Nk=-12.5km)


texts: Can military aircraft send out false ADS-B tracking information?

texts:
Can most military and VIP aircraft out of Andrews AFB transmit false ADS-B signals?
Here is the ADS-B tracking of Navy P-3 Orion that seems to be violating Iranian air space tonight if the ADS-B is correct. An Iranian fighter was launched heading in it's direction but did not approach it. Two nights ago I was watching on globe.adsbexchange and flightaware the tracking of AF1 was transmitting. It was about 2 miles out from the air field for a landing and the ATC tower noted to ground crew VIP traffic is 10 miles out. It showed it landing when in fact it was still in the air. I know they are allowed to turn off their ADS-B anytime they need to for security reasons.


texts:
Does lift equal weight in level flight? Or does it equal weight + down pressure on the tail?

Added) Let's say the total weight of the aircraft on the ground was 100,000 lbs, and when it took off and leveled off, the down force from the tail was 10,000 lbs. Then what's the total lift required to support the level flight?


texts: What is the proper procedure to change altitude when changing heading?

texts:
I'm told that, depending on the heading of your aircraft, you have to fly at particular altitudes.  Which, of course, makes sense because having planes flying in opposite directions at the same altitude is just asking for a mid-air collision.

My question is this though:  What about when you are changing your heading?  Pretend, for example, that for some reason you need to go the exact opposite direction (so, we were going due west, but now we are going due east, for example.)  I know you have to gain or lose 1000ft.  But do you change altitude after the heading change, before, or during?

So: What's the proper procedure for changing altitude when you change headings?

Bonus points:

Is this made more complicated if you are flying Visual Flight Rules instead of Instrument Flight Rules?
Are all these rules thrown out the window in Class B and C controlled airspace?


texts: Can you guide me about the purpose of fine alignment in inertial navigation systems?

texts:
I am new in inertial navigation field. I have some confusion about fine alignment process of INS. I want to ask that what is purpose of fine alignment?

I know by process of alignment we find the initial attitude matrix from body frame to navigation frame (reference frame) which normally take place by two step

Coarse alignment
Fine alignment

a. what is major difference between both steps?

b. how fine alignment refine the output of coarse alignment? Does Fine alignment minimize the errors to get more accurate output? or Does Fine alignment re correct the initial attitude estimate by coarse alignment?

c. why sensor bias like accelerator and gyro bias and lever arm error are  estimated in Fine alignment process.


texts: Would shutting down the engine have prevented the Atlantic Southeast Airlines Flight 2311 crash?

texts:
In the crash of Atlantic Southeast Airlines Flight 2311, a worn propeller quill caused the propeller blades to go flat, which created enough drag on that side of the airplane to make the aircraft uncontrollable.

If this were to happen in flight, and the bad engine were completely shut down, would that reduce the drag enough to recover control?

Perhaps in the case of 2311, they might have been too low and too late, but in general, can this type of failure be recovered from? It seems that if the propeller were not being driven at high RPM by the engine that the drag might be less severe.


texts: Why does the UH60 have a titled tail rotor?

texts:
I've been looking at helicopter design recently, particularly UK military helicopters. I've noticed that most tail rotors are parallel/flush with the tail of the helicopter in most designs. When looking at the UH-60, I noticed that the tail rotor is diagonal WRT the tail (see image below).
My questions are:

Why is this?
Does this impact it's the ability to counter torque?
Does the rear rotor for the UH-60 have a component of lift?


texts: What’s the grey altitude depicted in the profile view on Jeppesen charts?

texts: What’s the altitude depicted in grey in the profile view? Why there are some approaches that this isn’t depicted and some are?


texts: How is a 14 CFR 101 sUAS NOTAM filed for an unregistered aircraft?

texts:
FAA promotes the utilization of NOTAMs to announce sUAS operations, and requires it in 333 exemptions and some 107 waivers. However, sUAS (drones / model aircraft) under 14 CFR 101 have been determined to not require registration.

Drone NOTAM entries are not possible without a registration number.

How, without registering a 101 model aircraft, may one file a Drone NOTAM?

EDIT 15 June 2020:  Regulations have changed, and now Exception for Recreational Flyers requires that aircraft 250g or greater be registerd.  This addresses this question, as the question was relevant to former part 101 recreational flyers, which has been changed to now require registration.

However, aircraft below 250g do not require registration, and a pseudo identifier, created by the owner may be used as a registration identifier.

I will create an answer for this question reflecting the current regulatory environment.


texts: What helicopter is this in The Walking Dead?

texts: The reason I am asking this is because I want to do a 3D model of it. You can see it in this screenshot from The Walking Dead. At first I thought it was a UH-1H, but the main rotor doesn't look anything like a UH-1H main rotor.


texts: What's the minimum allowed flying height of a light aircraft over a town?

texts: I mean a Light aircraft, in Germany and a town like Heidelberg. And I mean not landing, of course, but overflying.


texts: Are warnings generally "source-focused" or "effect-focused"?

texts:
I have trouble wording this question, please bear with me.
Sullenberger recently stated that the pilots of the fatal MAX flights where likely under sensory overload caused by "multiple, compounded alerts". Which makes me wonder: As a general rule of thumb in modern commercial aviation, do we try to alert pilots of the cause of an issue (this or that part is out of order, e.g. we lost a hydraulic pump), or of the effect (we cannot move the control surface anymore)?

Only alerting of the cause might make them overlook effects.
Only alerting of effects might take away a chance to solve/remedy the issue.
Alerting of both might be the overload mentioned before.

Or is there another system in place, like filtering or at least ordering warnings by severity? I am a software architect by trade, and we always go with "display the error in the earliest possible step, and ignore the rest." The rational is: Do not distract me with the facts that my paint job is getting blisters and my tires are flat, if we already determined that the car is on fire.


texts: How long does it take to issue an FAA medical certificate?

texts: How long does it take for the FAA to issue a medical certificate? Exam was 7/23 and haven’t heard anything since.


texts: When flying in uncontrolled airspace, which ATC frequency should I contact if I have an emergency?

texts:
Question 1: If I am flying in uncontrolled airspace and I have an emergency, should I report on 121.5MHz if no ATC is within line of sight communication (which means I cannot hear the ATC and the ATC cannot hear me)?

Question 2:
Which frequency should I use to report the emergency in the following scenario? When the emergency happens, the aircraft is in uncontrolled airspace but near or approaching controlled airspace. There is an ATC station which is in charge of that airspace and the aircraft is within the line of sight of ATC (which means I may hear them), but my onboard radio coverage (the green circle indicated in the picture) cannot reach the ATC station (which means ATC cannot hear me). Should I report on the ATC frequency as maybe some aircraft are flying in the area and can relay the emergency to notify the ATC? Or should I just keep reporting on the common radio frequency like 121.5MHz?


texts: Does a Boeing 737-800 Have a Ram Air Turbine (RAT)?

texts: I am travelling with Thomson on a Boeing 737-800 and wondered if it had a RAT?


texts: What is "Boost"/"Super Boost" in the PW127M/N?

texts:
This incident describes rejected take-off due to the "boost" being inoperable. The reason for the RTO is obvious: engine power lower than expected.

But what is this ominous "boost" technology?


texts: What happens when the surface ends at the laminar zone of the boundary layer?

texts:
When a body travels through any fluid, due to viscosity of the fluid a boundary layer is formed around the surface of the body which separates the velocity of the fluid inside the boundary layer(near the surface of object) to velocity of the fluid.The boundary layer consists of three zones laminar, transient and turbulent zones respectively.

Is it compulsory for all the three zones to exist in a boundary layer? If we consider a small smooth surface, is it possible that the surface ends at the laminar zone of the boundary layer and there is no turbulent zone in boundary layer over the surface? And if it is possible will there be a low pressure zone at the end of the surface or something?


texts: Why do we lean the mixture when the air become less dense?

texts:
In a carbureted engine at higher altitudes, less dense air means there is less air entering the engine. Wouldn't we want the mixture to be full rich to allow the maximum air into the engine?

I understand that the engine will become rough if we don't lean the engine. I'm asking what is going on? It seems like a decrease in air means we would need to open the mixture not close it.


texts: What is the difference between Flight data recorder and performance data recorder

texts:
Does Flight Data Recorder consists of performance data or both of them are recorded separately.
Do we also have flexibility when to start recording performance data like
Records the initial conditions at the cruise ,climb/des intersection, or current conditions


texts: Is there any benefit to sweep back on an ultralight?

texts:
Is there any benefit to sweep back on an ultralight of:

15 deg
30 deg
45 deg.
other?


texts: Where I can get historical jet fuels prices?

texts:
I would like to analyze jet fuels prices in 2014.

Where can I get jet fuel prices for 2014, only in USA and Russia?

As there are different types of fuels, it would be okay to get prices for one (believe, trends are the same) or for all types.


texts: When is flotation gear legally required for pilots and passengers on a non-commercial flight in a small airplane over water?

texts:
If I'm renting an airplane to fly myself and some friends over water beyond gliding distance, but within 50 nautical miles from the nearest shore, am I legally required to have any flotation devices whatsoever?

According to 91.205 if you are flying for hire over water you must have life preservers for each passenger. However, does renting an airplane for recreational use trigger this requirement? In other words does renting and aircraft from an FBO qualify as operation for hire for purposes of section 91.205?


texts: Why are many runways used just for departures/arrivals?

texts: At LAX and many other large airports they designate certain runways for landing or takeoffs Normally. Why is this? I think its inefficient use of available runways.


texts: What could lead to engine running hot on climb out?

texts:
I own a turbo Saratoga with an intercooler and gami's. The engine has 100 hrs so it is broken in and I can't get the cylinder head temps below 400 during my climb out and I am operating at full power.

This has required me to run a very low power setting to keep the temp below 400, but my climb rate is terrible.
I am running full rich from take off thru climb.

Does anyone have any ideas on what the problem might be?


texts:
I have a sport pilot license and fly my own SLSA (Special Light Sport Aircraft). I have all the required logbook hours signed off by my CFI for the PPL and 120 hours as PIC plus 80 dual student hours. Once I pass the PPL written test and obtain a 3rd class medical, would I be required to take a full oral test and check ride to obtain a PPL?

Notes:

SLSA: Special Light Sport Aircraft
CFI:  Certificated Flight Instructor
PIC:  Pilot In Command
PPL:  Private Pilot License

EDIT: Thanks for responding. I do have 3 night flying hours + 3 hours under the hood. I did all the required private pilot flying and ground school hours before deciding to go the light sport route. I'm thinking about about getting the private pilot license if and when the 3rd class medical is eliminated as a requirement. So, my question is - what would I be tested on for the private pilot checkride? Or would a checkride even be required?


texts: Where can I find a conceptual UML model of airline crewing activities?

texts:
I would like to know if anyone has created a UML model of the various elements of a typical crewing system. I have found online UML models for ticketing and reservation systems. However I would rather be interested in the crewing aspects. Here are the things I would like to model:

Flight Logs
Crew Activities
Pairings, legs
Etc...


texts: Should I keep specific distance from Class B?

texts: I was wondering if I fly my c172 in class E airspace, and Class B base was 5000 MSL. should I keep specific distance from Class B? or is it okay to go up to 4900 MSL but not reaching 5000 MSL?


texts: Is there a tool to plot locations within X nm of a position?

texts:
I'm looking for a tool to allow me to see what is within X nms or X hrs of my base airport. Is there such a thing?  I remember a small airport I flew to once had a large map with a string attached to a pin located at the airports location on the map.  There were concentric rings from the location stating 100/200/300....nm. I'm basically looking for something like that such that I could explore and look for locations that are off my normal radar of places I would typically visit.  I typically use landings.com for baseline flight planning but you need an origin and destination. It doesn't look like it allows what I'm asking for.

I'd even be happy if there was a hack for google maps etc. to do what I'm asking.


texts: What airfoil is used on the MQ-1B Predator's wing?

texts:
There are lot of UAV's in todays world to be re worked on. The General Atomics series of UCAVs is quite remarkable. I have selected MQ-1B Predator UAV, for an geometric analysis project(undergraduate).
Though the wing dimensions including root and tip chord's length are found at https://mq-1predator.weebly.com/design-and-specifications.html and the rest performance specifications for it is available at https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104469/mq-1b-predator/.
Still it isn't mentioned anywhere at websites and in factsheet too, about its "Airfoil profile".
I have been trying to figure it out.
Can anyone please help me out to ascertain MQ-1B's airfoil profile?


texts: Having declared a mental health condition in the past, how will this affect my plans to work as a pilot, and what should I do about it now?

texts:
About a year and a half ago I moved into an apartment, where pets are not permitted. In order to be able to bring my pet with me, I applied online and obtained an "Emotional Support Animal" letter that in effect, states that my mental health is such that I am unable to live without the animal. This obliged the landlord to permit me to bring the cat with me.

The pet did provide with me emotional support during a difficult time in my life but in retrospect having it declared an emotional support animal was probably not the correct treatment but I couldn't get the building to accept me any other way. Now I'm concerned that this letter is going to be my downfall. I've never been treated or medicated for anxiety or depression, never actually met or spoke to the therapist that issued the letter. I know I have to declare mental health treatment on my medxpress form before my AME... What should I do about this ESA letter?

If this letter keeps me from flying I may never forgive myself.  I figure my best bet is to call AOPA and speak to someone in their Medical department and to schedule a consultation with an AME. I would appreciate any advice.


texts: What is the usual or maximum speed during the push-back procedure of large commercial aircraft (say, B737, B787)? Is it fixed or dependent on the aircraft type or weight or anything else? Is it different for towbarless vs. towbar procedures?


texts: May a student continue a discontinued checkride if the CFI who endorsed them voids that endorsement?

texts:
The Situation
CFI Charlie endorses Student Sara's logbook for a checkride. Sara begins the checkride but discontinues, and receives a letter of discontinuance. So far so good.
Before Sara can reschedule the rest of the checkride, she and Charlie have a disagreement. Charlie has access to Sara's logbook and voids his endorsement by crosshatching the entire text of the endorsement before giving it back to her.
The questions

Is Charlie's endorsement actually considered void?

Sara has the letter of discontinuance in hand. Can she reschedule and complete the checkride without getting a new endorsement?


texts: Purpose of CHT drop in piston engine shutdown procedures?

texts: One of the items in the helicopter Robinson R22 (and possibly other piston engined aircraft) shutdown procedure is to wait for the Cylinder Head Temperature to drop to a lower temperature. What is the purpose of this?


texts: Why is wave drag non-zero for a flow without shockwaves?

texts:
Wave drag is often defined as the component of drag that arises due to the presence of shockwaves. Shocks result in an entropy rise and a corresponding increase in drag. However, when using Supersonic Potential Flow Theory (Ackeret Theory), the flow is assumed to be fully isentropic (i.e. no shockwaves) and it can be shown (see Bertin, Houghton, Anderson for reference) that the wave drag is non-zero for such flows. So, what is the mechanism behind why the wave drag arises in such a flow without shocks?

More Detail (from Aerodynamics for Engineers by Bertin)


texts: How does an aft center of gravity affect the minimum control speed on ground (Vmcg)? Does it reduce all V-speeds?


texts: How to calculate the the variation of Cl wrt the angle of defection of the elevator?

texts:
I've checked the lift requirements of the aircraft and selected an optimal airfoil and designed a wing with dimensions of MAC 47cm and semi-span of 163.2 cm and a airfoil S1223. The horizontal stabilizer has a MAC of 17.5cm and semi span of 50cm with NACA 0012.
How can I calculate the change in Cl of the elevator with respect to the angle of deflection of the elevator?


texts: Why is one of two parallel runways sometimes closed in foggy weather?

texts:
A few times, when flying into SFO, me and my fellow passengers were informed that due to foggy weather one of two parallel runways there is closed, causing delays. So, a few questions:

Why can only one runway be used during fog? During an instrument landing, if the instruments are precise enough to land the plane exactly in the middle of one runway, then surely they are precise enough to differentiate between two runways?
Is this standard practice in all airports or something specific to SFO? Is there some minimum distance between parallel runways above which it is safe to keep them both open in foggy weather?


texts: What is the background of the maximum altitude formula?

texts:
This question What determines the maximum altitude a plane can reach? has a formula at Peter Kämpf's answer :

$$\rho_{min} = \frac{2\cdot m\cdot g}{(Mach^2 \cdot c_L)_{max}\cdot a^2\cdot S}$$

Does anybody know what's the name of the formula or who has developed it?
Could anyone explain why $Mach^2 \cdot c_L = 0.4$ is a good value? What determines good or bad values for airfoils or what type of airfoils is requested?


texts: Is there a specific procedure for grounding a pilot?

texts:
When a pilot gets grounded by the FAA, is there a specific procedure that happens?

I have heard of situations where the pilot is recommended or told to ground themselves. Is this the same as if the FAA were to do it or does the pilot just say "I'm not going to fly today"?


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

texts: Other than the downwash effect, what other factors that affect the flow to the horizontal stabilizer? such as Dynamic Pressure? Air Flow Disturbance?


texts: What happens if a helicopter engine fails at 20,000 feet?

texts:
A fixed wing aircraft is able to glide in case of an engine failure and potentially land safely.

What would happen if a helicopter engine fails at high altitude?

Is it possibly to land it safely?


texts: Does contra-rotating vs regular propellers, have any effect on icing?

texts: I am trying to understand whether can there be any correlation between the contra-rotating propellers and the ice accretion over the wing ? For instance, is there any evidence that ice accretion is more in regular propellers when compared to a contra-rotating propeller ?


texts: How long to receive FAA wings lapel pin?

texts: Did anyone request FAA wings lapel pin? If yes, how much time do they take to ship and receive? Do you know if I requested all three phases at once will I get three or just one pin?


texts: Are there legal limits associated with the use of the autopilot in the US?

texts:
A lot of new avionics basically fly small planes for you. Looking at a Beechcraft with a pretty cool glass cockpit, it claims to do everything for you except within 50 feet of the ground. Basically you takeoff and land and nothing else according to the advertising.

I'm planning on doing more than that, but it made me curious, is the "within 50 feet of the ground" non-autopilot part because it's a legal requirement or because it's just the trickiest part and they don't want to deal with that?

Is there a legal requirement in the US for part of the flight to be piloted manually, whether that be percentage or just takeoff and landing or is that just the hardest part to automate? If so, can it be remotely piloted?


texts: Is there any way we can predict an air crash?

texts:
Is there any way we can predict a crash from the system inputs?

The question arises from this discussion.


texts: Is there a database containing detailed information about airfields and runways?

texts:
Does an electronic database containing the various civil runways in a given region of the world exists?

Maybe even categorized by type (e.g., grass vs asphalt), length, if controlled or not, etc.

If it does not exists, what would be the effort related to creating one?

As Danny Beckett mentioned in comments, OurAirports has such data, but there is a "use at your own risk" disclaimer. May any source be reliable and trustworthy or will I find such disclaimer on all sources?


texts: Why is the Inertial Reference System not used to determine true altitude?

texts:
Given three very accurate laser gyros and accelerometers I believe the Inertial Reference System (IRS) should be as accurate in determining true altitude as it is in determining lat/long, providing the aerodrome elevation was supplied at initialization.

I realize that pressure and density altitude are what is used in aviation, but could the IRS be used as a backup? Could it replace or backup a radar altimeter for approach/landing?


texts:
Could somebody please explain me the differences between using the OBS and the Heading Indicator? As much as I could understand, once you tune into the VOR, the OBS starts to show how much deflection/ deviation is there. You then turn the OBS to align the needle which shows the direction (in terms of angles) that you need to fly to reach that VOR.

Does this mean that the OBS is the instrument to derive the direction, and serves no direct purpose in terms of heading? I.e. the Heading Indicator is the one that then should align be flying in that new direction, right?


texts: How does Chicago O'Hare's tower sequence aircraft at peak capacity?

texts:
This older question asks at what interval planes take off and land from ORD. The accepted answer (one takeoff or landing every 30-40 seconds) jives with my math: 2416 operations a day on average, with winds in a non-cardinal direction all those flights must use just two runways, so worst-case each runway would have a plane rolling along it every 75 seconds round the clock (so a plane takes off or lands from somewhere in the airport every 37.5 seconds).

My question is, how? At that rate, approaching planes would be spaced a scant two and a half minutes apart, and as soon as a landing plane passed over the numbers, a departing plane would be told to line up, then to take off as soon as the landing plane had cleared the runway, and if they hesitate even a few seconds the plane behind them would have to go around. How is this traffic density maintained long-term, especially since, like any airport, it has peak periods of activity exceeding the average?

Follow-up question; is ORD as bad as it gets, or are there "denser" airports with lower total aircraft movements but fewer runways? I heard Heathrow is so bad its airspace is ICAO Class A, prohibiting VFR flights entirely, in part due to the fact the airport handles practically every international flight into London on just two runways.


texts: Why do some aircraft have to have the landing gear pinned prior to towing?

texts:
The Phenom 300 require all three gear to be pinned before towing. I assume there are other aircraft with the same restrictions.

The nose gear is understandable, due to the link being pinned out of the way to allow a larger range of movement of the nose gear.

But why the main gear? Does it have something to do with the trailing link style of the mains?


texts: Is a Mode S transponder required as part of TCAS I?


texts: Where does the oxygen come from in the deployable breathing masks?

texts: I don't know what they are called. In case of emergency like smoke they deploy, but where do this oxygen come from.


texts: Why the inward engines-placement on the An-124?

texts:
I am curious as to why the engines (specifically engines 1 & 4) are positioned far closer to the fuselage on the An-124 compared to a typical 4-engined jet.

I am curious as to whether this design was totally due to wing aerodynamics, or if it may also be related to the shoulder wing design & wing droop when not flying.

Overlay that matches the wingspan of a 747-100 (top) to an An-124, showing the more inward placement of the jet engines.


texts: What other advantage(s) does an adjustable prop give you?

texts:
From what I understand, the purpose of a variable-pitch propeller (be it manually adjustable, or constant speed) is that it allows the engine to always operate at its most efficient speed, much like the transmission of a car. Is that correct? If so, if an airplane were to accomplish that another way (say, a hybrid gas-electric drive, or an actual transmission with shiftable gears*), would there be any other advantage to having an adjustable propeller?
*No, I don't know why you would want to mount a car transmission on an airplane. It's a hypothetical question. But now I have this picture in my head of a twin-engine plane with two gear shifts in the cockpit and two clutch pedals next to the rudder pedals.


texts: How do radio altimeter systems compensate for objects on the ground?

texts:
My understanding of a radio altimeter is that it can provide more accurate altitude readings below the transition level.

It occurred to me a number of days ago whilst sitting beneath the glide path at my local airport that surely discrepancies must arise when using radio altimeters due to objects such a parked vehicles and trees beneath the flight path of the aircraft.

Are these negligible or are they taken into account by the system or the crew?


texts: Which civilian airport has the most runways (current and planned)?

texts: I just read Is the airport capacity related to number of runways? . While there are a host of factors, the idea of more runways is obviously so that more flights come in and out. Which is the biggest and baddest airport which has the largest number of people as well as aircraft coming in and out. Few days back I read that the Chinese have some ambitious plan for the Beijing Airport. I do not know how many runaways it would have (the newspaper article didn't tell/share that info.) but would be interested to know which Airport is the king?