texts: Could a private pilot violate 'commercial' rules if there is no compensation or expense sharing at all?

texts:
How might a private pilot run into regulatory trouble by flying a passenger if they don't receive any compensation at  all? I'm interested in some specific scenarios. In all of these cases, let's assume the pilot receives no compensation of any kind, and pays all costs himself. The passenger makes no contribution whatsoever. There are no exchanges of services, no favours, no under-the-table deals. Also assume that none of the activities mentioned are in any way concerned with the employment or other business activities of either pilot or passenger.

The pilot flies the passenger somewhere the passenger wasn't planning on going, but nonetheless enjoys. I'm assuming this is not a problem, and happens most days
The pilot flies the passenger to visit a family member, one they wouldn't have visited otherwise.
The pilot flies the passenger to a recreational event, which they are attending.
The pilot flies the passenger to a recreational event, which only the passenger is attending.

Again, no money changes hands, no compensation of any kind, pilot pays all the costs.
US regulations. And please, specific citations of cases or regulations.
EDIT: Since this appears to be a source of confusion, let me repeat for the third time in the question: there is no compensation or expense sharing and nothing of value changes hands. The pilot pays all costs, at exactly the same rate as he would if he was flying alone. There is no 'goodwill' expected, no future business deals, nothing.


texts: What's the difference between 'Go Around' and 'Pull Up'?

texts: We use on the standard RT (radio telephony) Go Around. But what's the difference between Go Around and Pull Up?


texts: Are there specific names for airport vehicles used for de-icing?

texts: Do de-icing vehicles used at airports for de-/anti-icing procedures have special names? I-ve searched the internet but have not found the exact names of these vehicles.


texts: Engine out over a mountain road. Do you land upwind or up hill?

texts: You're flying solo in a late-model, fixed-gear Cessna 172 with half-full fuel tanks.  You are at 1000 feet AGL, 100 knots indicated, directly above the middle of a 2000 foot long straight section of paved road.  There is a steady 15 knot wind blowing up the 10 degree, wide, flat and clear slope that the road runs straight up.  Your engine suddenly seizes, prop horizontal, with no possibility of restarting it.  Everything else about the aircraft is perfectly functional and the height of the terrain is not significantly above sea level for performance purposes.  The road section heading is 360 degrees, due north up the hill.  Choose any initial heading for the engine failure and remember it occurs directly over the mid-point of the road section (runway).  Please provide information on the specific flight segments in terms of speed, turn rate, descent rate, etc. and consider the effects of the wind blowing directly upslope (without any crosswind component with respect to the roadway).  Explain why your answer is (nearly) optimal.  How do you make the safe landing?


texts: How was this airline (statistically) never had a fatal incident?

texts:
Ryanair make around 725,044 flights per year. This They have been operating for 35 years, so have accrued around 25,376,540 flights.

They have also never had any fatal incidents or even major injuries related to a flight. Statistically, they should have had around 2 or 3 by now at least.

How and why is this airline so much safer, statistically (based on average commercial aviation fatality statistics) than almost any other airline in the world? (Easyjet being the closest with a similar perfect safety record).


texts:
Obama came to Greece and then to Germany. That's a long trip, even for the majestic Jumbo. There was a lot of discussion about where the aircraft was refuelled during that trip. Do we know, in general, where Air Force One is refueled?

There were claims that it was refuelled in the air by American aircraft, but isn't that more costly than refuelling on the ground?


texts: Is it possible that derated thrust takeoffs are safer than normal takeoffs?

texts:
The reason for my arguments here are (assuming that you have sufficient runway distance):

That with less thrust, less force should also be required to hold the aircraft as desired, and possibly the aircraft should be easier to control and fly when the engine fails than if it does so with the thrust set to full blast.

An engine event, such as a bird strike, might (?) be less likely to have catastrophic consequences for e.g. the turbine blades when they are not running at full thrust and their design limits.

Never having actually commanded an aircraft, are any of these ideas correct?


texts: Are there FAA rules about changing an airport name from Municipal to Regional?

texts: Are there any FAA requirements to be met or stipulations for an airport to change its name from Municipal to Regional?


texts: Where can I find records of old FAA registrations?

texts: I know where to find details for FAA N-Number registrations. But where can I find records and details on older FAA NC, NR, NL, and NX numbers?


texts: Where can the airspace boundary coordinates for Fayetteville TRACON be found?

texts:
I would like a map depicting the airspace owned by Fayetteville TRACON that includes lat/long coordinates (i.e. not just a cartoon-y outline with no information). Ideally, I'd like to find a site whereby I can look up the airspace map for any ATC facility, but, for the moment, I'd like Fayetteville.

Any thoughts?


texts: Does anyone know what this set of aviation wings signifies?

texts:
I stumbled upon this set of aviation wings whilst searching through a box of old things, though I'm at a loss as to their origin, and what they symbolise.

Judging from the lack of skill used to craft the item (Seems the mold had an off day), I doubt it's rare, though I could, very likely, be wrong.

Other than what you can see in the picture, the wings are roughly two inches long, and made of metal; sterling silver, perhaps?

As for background information, I did have Polish family who fought during WW2 in the west, and another who served in the RAF Regiment. There really isn't much else I can tell you, so I apologise for the ambiguity.

Still, I hope you can help!


texts: What valve would be the best for a model rocket with a hybrid engine?

texts: I am planning on building a model rocket with a hybrid engine. I am trying to find the best valve that could be used for the MOV, main oxygen valve. I plan to use gaseous oxygen and would like the valve to be electrically actuated, and have the ability to throttle. Does anybody have any recommendations for a good valve to use? Thank you.


texts:
When I got my pilots license in 1975, a lost airplane could call almost any FSS and get a DF (Directional Finder) steer. The range was probably upto 30mi. I would request a practice one every 3-4 years. The last practice DF steer I did was 15-20yrs ago.

Can you still get DF Steers (or an equivalent) from FSS?


texts: Why is the Airbus A320 permitted to carry 180 passengers, instead of the maximum 179 allowed?

texts:
The EASA regulations give the following requirement for number of emergency exits:

If then the Airbus A320 is certified to carry 180 passengers, it seems to me that it falls just outside the minimum bracket of 2x Type I exits and 2x Type III exits and it should then have a pair of additional Type III exits to be able to accommodate 180 passengers.

However, various sources give the emergency exits as (link):

This configuration, in my opinion only allows 179 passengers, not 180.

Is there some clause I am missing?


texts: In aircraft air conditioning systems what are the differences between the air cycle machine system and the displacement blower type system?

texts: I have seen reference to both these different air conditioning systems but can't understand what the key differences are and where each system would likely be found.. I.e is one system preferable over another system on a particular aircraft type?


texts: In theory, can jetliners remain controllable after losing the entire tail section?

texts:
The scenario here is a detachment of the tail,one with the whole empennage.
Could a variant of an existing model of swept winged jet airliner be made to remain controllable, using ailerons, differential flaps, differential spoilers and differential thrust, used for pitch, roll and yaw, regulated by an appropriate autopilot program, and with no other modifications?


texts: How often do V1 cuts come up in airline sim training?

texts: Just how often do airline pilots practice V1 cuts when in the sim? Is it the kind of thing that turns up practically every sim session, or is it something that's much more sporadic?


texts: Why were the F-35B lift fan doors changed after flight testing?

texts: Why were the F-35's lift fan doors redesigned from those used during flight tests? The original design had two main doors which opened to each side, rather than the “car hood” style door used in production F-35B aircraft.


texts: Are there two types of runway holding position sign?

texts:
I came across this section on runway holding position marking while reading Jeppesen Airway Manual, which got me very confused.

My question is: Is Pattern B describing another type of runway holding position sign other than the one described in Pattern A? Or is it just describing the ILS critical area boundary marking for CAT II & III approaches? I'm asking this question because I've never heard in my whole aviation career that there are "two" runway holding position markings, nor seen one.


texts: How does the load transfer from a prop to the airframe?

texts:
I was just watching this video...

Restoration and startup of a Wright 1820 Cyclone

...and it got me thinking: a propeller shoves back air, and this creates a forward force on the prop. The prop attached to a shaft, and the prop is tugging on the shaft. Both the shaft and the prop are rotating.

The airframe on the other hand is (relatively) stationary. Yet the airframe depends on the rotating prop to pull it in the desired direction of trust.

This means there is an interface somewhere, between the rotating shaft and the rest of the engine, and that interface transfers all the thrust of the propshaft to the engine, and then the engine in turn transfers that force to the air frame.

That to me sounds like the mother of all bearings! What does such a bearing look like?! Or is there some other mechanical principle/device in play?


texts: What techniques, tools, or instruments are used while performing zero-g parabolic dives?

texts:
There are companies that sell "zero g" rides, where the aircraft is configured specifically to take people and possibly experiments through a parabolic dive to experience a short period of micro-gravity (possibly not the proper term).

This question asks about possible risks associated with the maneuver.

I'm interested in what specific techniques, tools, or instruments are in the cockpit that allow the pilots to properly follow the proper trajectory, while not pounding the occupants against the walls of the aircraft?

A G meter seems pretty obvious, but are there other less common things used? Are there special techniques for managing energy buildup, or for reminding the pilot when to pull out of the dive so as not to over-stress the air-frame?

Any other interesting information that I may not be thinking of in a similar vein is also welcome.


texts: What materials are used to make up a combustion chamber?

texts: What type of materials are used to make up the different sections such as the linings of the combustion chambers in a gas turbine engine. Do these type of materials vary for the different types of gas turbine Engines such as the multiple-can type, annular and cannular.


texts: Why is landing not usually a continuous descent?

texts:
I have noticed on commercial flights (Ryanair, Boeing 737 specifically), that during the last 20 - 30 minutes of the flight, the aircraft alternates between descending and ascending pitch.

Why is this? Why not just gradually descend?

Further info: The route flown was London, UK to Budapest, Hungary.


texts: What is the airspeed velocity of an unladen swallow?

texts:
I'm considering the airspeed velocity of an unladen swallow because the swallow may present an opportunity for the observation of nature to lead to better design in aviation. Many technologies built by humans are inspired by designs in nature.

If one were to set out to determine the airspeed velocity of an unladen swallow, how might they go about this?


texts: Is it right to extend flaps only in the white arc?

texts:
If the cruise speed is >80kts on the downwind leg but I can only extend flaps in the white arc, am I right in saying I need to get to the white arc, even if I'm on - for example - 100kts?

For reference, note the 'white arc' on this airspeed indicator.


texts: How much altitude can a glider gain only from losing speed?

texts:
Say we have a glider flying near its top speed. If pilot decides to "trade speed for altitude" how much can it climb before hitting stall speed? Assuming pilot will use most effective climb rate for the task.
I know it depends on many factors, but what kind of figures are realistic?
Reverse situation - how much altitude glider needs to gain speed (say its top speed)?


texts: Are the airspace times of operation days of the week in local or Zulu time?

texts:
The margin of the Enroute High sectional H-4 claims that the times of operation of the airspace R-5107K near El Paso are "1400-0300Z, MON-FRI" (and other times by NOTAM).

If the days of the week are Zulu time then by converting this to local time would yield "0800-2100, MON-THU".

You could argue against this interpretation because usually, we use the days of the week to reference the starting time, which would mean that the airspace is available starting at "1400Z MON-FRI" which is still "0800 MON-FRI" when converted to local.

But that doesn't explain that on the Enroute Low sectional L-5 the OUTLAW MOA is available "0100-0500Z, MON-FRI by NOTAM".

If the days of the week are ZUlu time, converting that starting time to local time would yield "1800-2200, SUN-THU".

Assuming the NOTAM for this airspace is active, do they really mean that the airspace is active "1800-2200, SUN-THU"? or do they mean that it is active "1800-2200, MON-FRI"?


texts: Can this aircraft be identified by the exposure pattern of its flashing lights?

texts:
Can the aircraft on the attached photo be identified from the light pattern?  While photographing this globular cluster (M 13) in Hercules, an aircraft passed through the FOV.

The width between the outer lights is 3 arc minutes and the exposure time was 15 seconds.

The photo was taken on April 23, 2019, 10:28 PM at James River State Park, Gladstone, VA.


texts: Help with this flying machine. I think it is a concept / prototype designed in Europe in the nineteenth century.


texts: What are design or functional differences between sticks and yokes?

texts:
I've been flying Cessna 172 & 182's my whole flying life up to this point.  I know that Cirruses (Cirri?) have a "side yoke" and Diamonds, Citabrias and others have control sticks coming up through the seat.

Is this a design difference or are there actual functional differences between airplanes that have control yokes (like Cessna 182's) or sticks (like Diamonds) or side yokes (like Cirrus)?

For example, I realize that with the side yoke offers more legroom perhaps, but are there reasons beyond that - like pull/push force required?


texts:
For a hobbyist looking to write an autopilot program for a mode lUAV/drone, what are the aviation related considerations that would be involved in its design?  How could things like the ADC (air data computer), or pitot static system, be utilized to control bank angles and decent rates?  Are there any specific rules of thumb that would assist the autopilot in making smooth corrections?  For example, how should I calculate the max VSI in a climb or when approaching a level-off altitude, and is there a rule of thumb for bank angle in a turn?

Your answers will guide me in asking an educated question at the Programmers StackExchange and get programming specific advice on how to proceed.


texts: What does "E" stand for in a polar curve?

texts: In the following polar curve, there is a symbol "E" with the number 33.5 next to it. What does this mean?


texts: How does the aircraft keeps propelling forward when airflow and thrust are not aligned?

texts:
Assume an aircraft is flying at an angle of attack of 10 degrees, and that the incidence angle between the aircraft fuselage and the wing as well as the angle between the wing and the engine mount is also 0 degrees, the thrust force is at 10 degrees relative to the incoming velocity. My question is, since there exists an angle between the incoming the airflow and the thrust force, how does the aircraft keeps propelling forward straight?
I mean if I break down the thrust force into its components, then one component can be added in the direction of lift, and other component can be used to counteract the drag. But why would this make the aircraft to keep moving in a straight path? Because aircraft itself doesn't know how the component breakdown should be established, and also it just sees a resultant thrust force. Moreover, theoretically, I can make the component breakdown of the Thrust force using a different co-ordinate system, but still why would the aircraft keep on propelling in the same straight direction?


texts:
What airfoil design does the MQ-9 Reaper UAV use?  Alternatively, what similar airfoil designs exist?

I'm running simulations for the effects of vortex generators for a school project and I would like to study the Reaper drones.


texts: The whole purpose of an ER model is to increase range and by doing that you need to increase the amount of fuel stored in the wings. EX: Boeing 737-900, Boeing 737-900ER. Is the wing area increased or is their another way to increase fuel capacity.Source:(https://en.wikipedia.org/wiki/Boeing_737_Next_Generation#/media/File:Lionair_737-900_ER_first_flight.jpg)


texts:
Does anyone knows what type of plane is this and its model?

(Source: YouTube channel AssombradO.com.br)


texts: Aircraft Identification: What single-engine, T-tail, commuter aircraft has a single prop but sounds like a jet?

texts:
My morning walk takes me past Hillsboro Airport, Portland, Oregon (HIO), and today I saw a rather strange plane landing.  It was a small commuter-size plane (6 passenger windows on each side), with a single surprisingly large propeller on the nose.  While landing it sounded much more like a jet than a prop.  The tail was "T" shaped and I thought I saw a jet exhaust at the back of the fuselage.

Was I imagining this, or does such a craft exist?

Sorry I didn't get a picture.


texts: Why did narrowbody jetliners take so long to switch over to high-bypass engines?

texts:
High-bypass turbofans were introduced into the airliner market around 1970, when the first widebody jetliners were released (the 747 was first, followed in rapid succession by the DC-10, L-1011, and A300); however, narrowbodies continued to rely on low-bypass turbofans (primarily the Pratt & Whitney JT8D) for considerably longer.  To the best of my knowledge, the first narrowbody powered by high-bypass engines was the DC-8-70 (a re-engining of the DC-8-60), which entered service in 1982; the first narrowbody built with high-bypass turbofans, the 757, did not enter service until 1983.  As for the other narrowbodies of the time:

707, 720, 1-11, F28: No high-bypass version ever became available (although high-bypass versions of the 707 and 1-11 were proposed, they never entered production).
727: The only 727s that ever flew with high-bypass engines were four 727-100s reengined and renamed 727-100QFs in 1992.
737: The first high-bypass version, the 737-300, was only introduced in 1984.
DC-9: Stubbornly held onto the JT8D into the mid-1990s, only switching to high-bypass engines with the DC-9-90.

What kept the narrowbodies from immediately, or almost immediately, taking advantage of the greater power and lesser fuel consumption and noise of high-bypass turbofans?


texts: Which European (EASA, EU) regulation corresponds to US FAR 91.13 on "careless or reckless" operation of aircraft?

texts:
The US has 14 CFR 91.13 about "careless or reckless" operation of aircraft, as a sort of catch-all for activities which are not explicitly prohibited by the regulations but which are still a bad idea and risks to, or actually, puts others in danger:

  § 91.13 Careless or reckless operation.

  (a) Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.

  (b) Aircraft operations other than for the purpose of air navigation. No person may operate an aircraft, other than for the purpose of air navigation, on any part of the surface of an airport used by aircraft for air commerce (including areas used by those aircraft for receiving or discharging persons or cargo), in a careless or reckless manner so as to endanger the life or property of another.

I have a hard time imagining that Europe doesn't have a similar statute, but I can't seem to find anything looking through Part-FCL or my local regulations.

What is the EASA or EU regulation corresponding to the US FAR 91.13?


texts: Does the tailwind component always have the same absolute value as the headwind component?

texts:
If we are on course 360 and we have crosswind from 020 at 20 kts...does the amount of head wind on this leg equal the amount of tailwind on the reciprocal course (i.e. 180)?

To amplify the question with an example:

TAS:   260kts
Wind velocity: 310/35 kts

Given the above information, calculate ground speed on courses 240T and 060T.

When I use e6b+ aviation calculators, I get the following answers:

On a course of 240, the ground speed is 246kts. This is 14kts slower than the true airspeed.
On a course of 060, the ground speed is 270kts. This is 10kts faster
than the true airspeed.

Since I believe the headwind and tailwind components should be equal, the question is: why is there a difference of 4kts between the computed headwind component and the computed tailwind component


texts: How can a pilot anticipate cloud formation?

texts:
I read a few articles and a book about cloud forming, but I didn't really understand it.

Can anybody explain in simple terms how clouds form?
As a pilot, what factors that contribute to cloud formation can I anticipate?

Where do the terms Saturated Adiabatic Lapse Rate (SALR), Dry Adiabatic Lapse Rate  (DALR), Environmental Lapse Rate (ELR) and dewpoint fit into it all?


texts: Why is the FDR and CVR put into water again after a water crash?

texts: When a plane crashes in the water and the investigator team looks for the FDR and CVR, why do they put it in a container of water when they find it ?


texts: What is communicated between flight crew and cabin crew during flight?

texts:
During a typical trans-atlantic flight, can anyone list communication between flight crew and cabin crew?

I am interested in "mandatory", i.e. safety-relevant communication between the flight deck and the cabin, such as the before take-off and before landing notifications from the flight deck to the cabin crew.

What information must be communicated (by law) according to, e.g., ICAO or a major country jurisdiction?

Let's exclude any information regarding passengers, pax health issues, operational delays, meals, anything that is not directly safety relevant.


texts:
I read the night effect takes place in radio navigation, especially VOR and NDB. My questions are:

What is its nature?
Why does it occur?
What are the consequences of it?


texts: Is a recoil start (hand propping) allowed if it isn't mentioned in the aircraft manual?

texts: Is a recoil start (hand propping) allowed without it being referenced in the aircraft manual? In a Cessna 150, for example.


texts: What is the fuel temperature in the tanks during a flight?

texts:
I'm trying to estimate the temperature of fuel stored in wing tanks during the flight. In my situation, I'm considering two wing tanks of 2000 liters each, one on each wing, at 20°C before the flight

I've run some calculations (I can provide additional numbers if necessary), and I end up with a temperature of 17°C after more than two hours of cruise (Mach 0.5, FL250)

Does this number sound correct to you? I was expecting a much lower temperature. I took a constant mass of fuel, which is not the reality, but even 15°C for instance seems rather hot. What are the usual temperatures of fuel in airliners tanks?


texts: How do I obtain permission to fly in surface class E airspace under FAR-103?

texts:
I'm a paramotor pilot operating under FAR 103, and I'm trying to determine who I need to ask for permission to fly in class E airspace that extends to the surface and is designated for an airport. For reference, the particular airport that I am inquiring about is GFL.
This appears to be the relevant subpart of FAR 103: §103.17

No person may operate an ultralight vehicle within Class A, Class B, Class C, or Class D airspace or within the lateral boundaries of the surface area of Class E airspace designated for an airport unless that person has prior authorization from the ATC facility having jurisdiction over that airspace.

Before I was aware of this restriction, the airport manager granted permission for me to fly to and from the airport with my paramotor. I have an access card, and he made clear the rules I am to follow, such as radio procedures and where I can launch and land.
However, this field does not have a control tower. Do I need to obtain permission from someone else to comply with §103.17? I'm not sure who the ATC facility having jurisdiction over that airspace is.


texts: How do aircraft go off-course even with all their guidance technology?

texts: Pilots today have more than enough technology both in the cockpit and in the infrastructure that supports them to know with great precision where they are at any given time. How/why do they still sometimes go off-course?


texts: What is the difference between low energy warning and alpha floor in A320?

texts: I am always confused between both of these two. I know both signals low speed or high AOA


texts: What is the pressure distribution around a supersonic wing?

texts:
In subsonic flight the lift manifests itself at 25% of chord, but shifts to 50% of chord when the airplane goes supersonic.

Wondering about that made me think that the reason might be that there is high-pressure in front of the wing´s top-point like there is at the bottom in front of the low-point, and low pressure behind the low-point of the wing like there is behind the top-point.

Assuming a symmetrical biconvex wing profile, that would put the centre of lift the 50% of chord.

A symmetrical biconvex wing going straight forward would produce no lift, so it has to be put at an angle to compensate for the weight of the airplane and the Mach-tuck, but still the lift would manifest itself at 50% of chord "seen my way" - and that gets more and more the faster the plane goes as the AoA gets closer to 0.

A couple of extra questions: at what AoA is a fighter (F-16/18/22/35/Rafaele/Typhoon/Gripen) flying with in low (M 1.3) and high (M 1.8) supersonic flight?

Do fighters have symmetrical biconvex wings or do their wings have a camber?


texts: What would be the feasibility of an auto-rotating landing gear system?

texts: Has a feasibility study been considered that would allow for auto-rotation of heavy commercial aircraft landing wheels so that tire rotation matches air speed pre-landing?


texts: Are passengers allowed to travel seatless(on the floor)?

texts:
I was told that a flight in Europe carried two passengers on the floor, because their purchased seats didn't exist. BBC.

Is that allowed?

For example, in Greece, a bus is not allowed to travel with any passenger on the floor (or equivalently standing), so allowing a flight to do so seems surprising!


texts: How do you start a jet engine if the start valve is stuck closed?

texts: I was recently on a flight aboard an Airbus A380 where the flight was delayed 2 hours. The reason was claimed to be a start valve fault on engine #4, where it was stuck closed. According to the captain, they were able to get the engine started after manually starting the engine at the gate. How does this work?


texts: What are the requirements for logging SIC time?

texts:
I am going from KPRC to KVGT with a friend in his C-182.  I don't have a high-performance endorsement, but can I -- as a private pilot -- log as SIC at any time during our flight?

If so, what rules do I have to follow?

From what I understand:

I can log SIC time since the aircraft is a SEL
I can't log landings, obviously
And SIC time really doesn't mean anything

Am I right in assuming those things?


texts: Would adding a slat and a slotted flap increase the max CL of a multi element airfoil to 6.5?

texts:
Would adding a slat and a slotted flap increase the  of a multi element foil to 6.5?

I understand, as a general rule, the max $C_L$ for a classic NACA airfoil is as follows:

Base: 1.5
Slat: + 0.7
Slotted flap: + 1.3
Total $C_L$: 3.5

But with a Selig multi-element foil, the starting max $C_L$ is around 4.5.

Would adding a slat and flap to a Selig airfoil, with a 20° deflection of the main foil, increase the  $C_{L_{max}}$ to anything close to 6.5? Assume a Reynolds number in the 600-900k range.

Here is a pic of the foil:


texts: Do runway markings vary from country to country?

texts:
I understand that most of the airports should follow FAA/ICAO for runway markings but most of the countries have their own standardization orgs. So, how much do the runway markings vary from USA to Europe?

Edit: We are mainly looking for the big commercial airplanes and not the smaller and private strips which handles only big jets for commercial operations.


texts: How does the airflow around winglets reduce drag?

texts: I am familiar with the basic aerodynamics of wingtip vortex generation and I know that winglets reduce drag by reducing wingtip vortex generation.  I have never seen any illustration of exactly how winglets interact with wingtip vortices to do this.  I have also heard there is a small thrust component to the winglet's lift but am also unable to visualize this as well.  The multiple designs in use are confusing.  Why not just curve the end of the wing down to inhibit the vortex from spilling upwards?


texts:
everybody!
I'm new with PPL license.
To continue for ME, IR, CPL I have to be PIC for some hours.
So, I have to rent aircraft anywhere and do my time building.
As for me, It's cheaper to do it outside EASA, for example in US or Russia.
What I have to have in that case (except my PPL Validation)?
And how I have to confirm my logbook entries (aircraft rental contract, etc)?
Thanks for detailed explanation!


texts:
When trying to calculate, from first principles, the lift produced by the rotor of an autogyro, I have tried imagining the rotor as a circular flat wing set at an angle to the relative wind. The mass flow rate would be the volume times density of the swept 'air tube' deflected down per unit time. That mass flow rate, times the airspeed and the sine of the deflection, will give the lift... And if the gyro is flying s/l, you'll know that lift = weight, so that the deflection angle can be calculated.
But I don't know how to estimate the area of the base of that 'air tube'. In some papers, I've seen that it's taken as a circle with a diameter equal to the wingspan, but I find that somewhat arbitrary...
Is there a rational criterion for that area...?


texts: Are ILS CAT IIIA minimums based on the radar altimeter or on barometric altitude?

texts:
From what I understand the CAT II ILS minimums on the far right are based on radar altimeter 102'AGL and barometric altitude DA(H) 429'MSL (100'ATL).

But what about the CAT IIIA minimums in the middle? What is DH50' based on? Above threshold level or above ground level?


texts: How to realistically model propeller static thrust?

texts:
I am graphing static thrust vs prop diameter for a 600 kW motor and a prop diameter up to 5 m. I have seen the post 'What is the equation for calculating static thrust?' and using its formula and fixed prop efficiency I get a pretty linear graph. At 5 m the thrust is 19 kN.

Structural factors become increasingly important at larger diameters, but what other aerodynamic factors (perhaps prop efficiency changes with diameter) need to be considered to make the graph more realistic?

Update - I assume the prop pitch can adjust to maximize static thrust, but the twist is optimized for high speed (200mph) flight. The engines full power is also available at the best speed for the size of prop being tested. This Equation to bind velocity, thrust and power simplified by assuming unitary engine efficiency is the same as what I have been using.

$$T_0 = \sqrt[\LARGE{3\:}]{P^2\cdot\eta_{Prop}^2\cdot\pi\cdot \frac{d_P^2}{2}\cdot\rho}$$


texts: Do Air Traffic Controllers have to remember stall speeds for different aircraft?

texts:
While dealing with Takeoffs and Landings controllers provide speeds to pilots for different phases of the flight, specially during a landing approach.

How do they know which speeds are safe for all the different models operating to and from their airport? Are they provided with that data daily or they have to remember those speeds?

If a general answer is not possible I would be more interested in knowing about stall speeds during a landing approach. Obviously they will be different for different aircraft in different conditions.


texts: What are the five leading theories for lift generation?

texts:
I don't know if you guys have seen the British comedy quiz show QI (brilliant show), but in episode 10 of series A (aptly called Aviation) Stephen Fry (the host) mentions that there are five leading theories of how lift is generated, but none are validated. he then goes on to say that this only affects out understanding of lift and not how we engineer wings.

Now I am aware of maybe two prevalent theories (Bernoulli's principle and Coanda Effect), what are the other three he is referring to? And would an approximate theory (or an empirically sound hypothesis) be enough to design aircrafts?

Edit: I am aware of the fact that our understanding of lift is pretty watertight. I just wanted know if there were other hypotheses that used to compete with our current theory. (They could have been proven wrong, I just wanted to know them)


texts: Why did the diverted Rome - Chicago flight dump its fuel?

texts: Having just read this story about a plane which was diverted to Belfast following a passenger's abusive and threatening behaviour, I was wondering why the plane had to dump its fuel (as explained in the news article). It seems quite wasteful, surely the airline would prefer the crew to pacify or apprehend the passenger and carry on to its destination.


texts: Do thrust reversers make more noise than engine at same RPM?

texts:
I'm talking about general aviation jet engines here. I live near an airport and I rarely listen engine noise on takeoff but always hear one during landing.
Would a jet engine at the same RPM make more noise when using thrust reverser than not using one?


texts: Why is a downwind wind speed given in wind checks for aircraft on final?

texts:
I have a quick question about wind checks. When I spotting at Sydney (YSSY), I often hear tower clearing aircraft to land and giving them spot wind checks at the runway threshold, all pretty standard.

What I don't understand is when that wind check contains a downwind component.  For example:

QFA32, Wind 160/10 Downwind 2, Cleared to land RWY 16R

(That is an example and not a wind scenario I've heard.)

Am I overthinking this? Is the downwind component just given when they are landing with a tailwind?


texts: What is the feasibility of fitting all aircraft with black boxes?

texts:
In the wake of the tragic helicopter crash on January 26,2020 which killed Kobe Bryant and eight other people, it would seem to make sense to follow transport category aircraft standards and fit all aircraft, except ultralights, LTA unpowered, or powered parachute, with a cockpit voice recorder and a flight data and GPS telemetry recorder?

These systems aren’t that heavy - roughly 10 lbs or so - so it would represent a minimal loss in useful load compared with other standard of optional equipment.  I’m guessing with a little ingenuity, such systems can be made lighter and better tailored to light aircraft.  And these systems have been indispensable in accident investigations and may well greatly improve light aircraft safety.  Modern AHARS systems retain some telemetry data, one of which was responsible for piecing together this stall spin accident of a Cirrus.

One downside may be the requirement to place these systems in the tail boom of an aircraft for maximum survivability in an accident, and placing even light equipment that far from the aircraft datum, can cause dramatic shifts in Moment and CG location.


texts: What device in western countries allows ATC to get clearances or search flight plans automatically?

texts: In Korea, there is a device called 'Flight data terminal' which enable air traffic controller to get clearance or search certain flight plans automatically. But I found that there is no 'FDT' in western countries. I believe there must be some devices whose functions are similar to FDT of Korea, so I want to know the name of that device.


texts: What does "storing an aircraft" technically mean?

texts:
I have read on wikipedia about airline fleets and you sometimes see that they have aircraft which they declare that have been stored.

Technically what does this mean? How do you store and aircraft? Being the plane out in the open air and susceptible to weather, wouldn't delicate parts and even the fuselage degrade quite quickly?

Are stored airplanes then reused or resold in the future?

Wouldn't it be more feasible just to sell them instead of storing them for a period of time?


texts: What is the aspect ratio of T-tail for common twin turboprops?

texts:
I'm trying to figure out typical AR values for a T-tail configuration (at the conseptual design phase). Working with Raymer I found this table:

I can see the typical AR values for the vertical tail but I cant find anything about the horizontal one. The only info that I got is that it should be lower than wing's AR. The aircraft that I'm interested about is a twin turboprop.


texts: Does the NTSB ever not follow up a preliminary report?

texts:
Two years ago, there was a fatal crash in Fredericksburg, VA in which 6 people died in a Beech 95-B55. For some reason, the story struck me, and I wrote a note to myself to follow up on it.

The NTSB published a preliminary report 12 days after the crash (on 8/24/2016) but has not published any report since then. Do investigations sometimes end at preliminary reports, or will they someday follow up with a final report?

The NTSB case is ERA16FA288. I searched the NTSB's "Aviation Accident Database & Synopses" page for all events in Virginia on 8/12/2016 (as well as googling the airplane's tail number), and couldn't find anything after that preliminary report.


texts: Circular arc airfoil wing: why does the wing nose down twist due to camber?

texts:
I am reading this paper:
"Computational Investigation of Microscale Shrouded Rotor
Aerodynamics in Hover" Vinod K. Lakshminarayan, James D. Baeder ; JOURNAL OF THE AMERICAN HELICOPTER SOCIETY56, 042002 (2011).

In part "Rotor and Shroud Configuration" (page 2), the paper said:

  " The blades used have a 2:1 taper starting at the 60% span location with the leading edge remaining straight and the trailing edge tapering toward the leading edge; this results in about 11 degrees nose down twist in this region due to the camber. The radius and the chord of the blade are 121 mm and 25 mm, respectively, making the aspect ratio equal to 4.84. A circular arc airfoil with 10% camber, 2% thickness, and leading edge sharpened from the 8% chord location is used."

I thought taper has nothing to do with angle of attack of airfoil section and the chord lines of every section lie in the same plane. How could the wing nose down due to camber?


texts: Why are CJ2+ Anti-Ice & De-Ice Systems separately controlled?

texts: Why are the CJ2+ anti-ice and de-ice systems separately controlled? Wouldn't it be easier for both systems to be controlled with one button/switch (minimize chance of error from occurring)? Are there any aircraft that have the two systems controlled by one button/switch that would be activated as soon as ice is detected?


texts: Why aren't large, low-speed propellers widely used?

texts:
I am trying to calculate different propellers for the simple case like helicopter moving slow up like 1 m/s or staying/hanging in one place.

From generic physics point of view it is more efficient to push back more mass with low speed, then to push back less mass with higher speed.

Efficiency (Kg/Watt) I mean how many thrust in kg I will get from 1 Watt of power.

I did calculation using Prop selector software as shown in screenshot below big propeller 4 meters with only 32 RPM procude 1kg of thrust and power is just 13 Watts. Speed of the end of propeller will be 6.7 m/s.

Small propeller 27 cm with 7000RPM with the same 1 kg thrust needs 176 Watts of power. Speed of the end of propeller will be 99 m/s. 13 times more power!

Red thrust in the screenshot means "propeller is stalled", but maybe this "stalled" does not make sence for static case, when propeller is not moving.

My question is Why this type of propeller (big diameter, but low speed) is not in use? Is it just practical consideration like big field will be needed if I make very big propeller, or my calculation is wrong or something else?


texts: What factors determine the power curve of a jet engine?

texts:
From YouTube

The L-39 in the video is powered by an Ivchenko AI-25, from the footage we see that the engine idles at 60% N1, and the taxi power setting is 70% N1. (The other lower-reading needle is the N2.) The same engine powers the Yak-40.

Compared to modern jet engines on airliners, those values are very high.

If 70% N1 is used to taxi, then I think the AI-25's power curve is exponential, and it starts off late. So in a sense there are only two thrust settings, i.e., narrow throttle range, and hard to fine tune.

The AI-25 is a medium bypass turbofan.

Update:

I've come across some power curves for jet engines, some are almost linear, some are exponential, and idle RPM varies.

So, what factors influence the idle RPM, and the shape of the power curve?


texts: What is the smallest aircraft to have a CVR / FDR?

texts:
I was wondering what is the smallest aircraft to have a CVR (Cockpit Voice Recorder) and/or FDR (Flight Data Recorder)?

Small single engine prop can sometimes have the avionics, like the G1000, that records some of the flight parameters on a memory card. But what about a proper CVR or FDR?

I'm not asking about military aviation, but more about general or small commercial airplanes.

I understand that it depends of the type of operation, but what is the smallest airplane to have a CVR/FDR on board?


texts: Impact of centre of gravity position on stall recovery

texts: Can somebody explain what is the impact of CoG position on stall recovery. I heard that stall speed is higher with forward CoG comapared to aft CoG, but does it have influence on stall recovery? Is it more or less difficult with some CoG position?


texts: What preflight passenger briefing items are required under Part 91?

texts:
I have been taught to use the SAFETY acronym, mostly for checkride purposes. Which of those items are explicitly required (give references please) to include on a PAX brief for non-compensatory pt 91 flight?

My most recent DPE told me that only the seatbelts and the emergency exits are actually required. I found in 91.107(a)(1) the seatbelt requirement but cannot find the emergency exit req. He is right? Are there others?

Note: this scenario is assumed excempt from 91.519.


texts: Is RTCA DO-260 Change 1 the same as DO-260A?

texts:
I am a bit confused as to the history and the naming for 260 documents. This is the timeline I perceived.
From earliest to latest:

DO-260                  ( September 13, 2000 )
DO-260 Change 1         ( June      27, 2006 )
DO-260B                 ( December  2,  2009 )
DO-260B Corrigendum 1   ( December  13, 2011 )
DO-260B Corrigendum 1   ( December  13, 2011 ).
This one says it is supplemental to DO-260B for corrections in regards about typographical errors, etc.

Am I missing something? Please correct me if I'm wrong.

At the moment I assume DO-260A is the same thing as DO-260 Change 1 yes? Another is what are the major differences between DO-260B and DO-260B Corrigendum 1 ? Thank you in advance.

Sources:
RTCA store website,
Fourth Meeting of APIRG_ICAO


texts:
Until recently, I was under the impression that CVRs will start recording as soon as the engines are started and turn off when the engines are stopped.

However, this is not the case given there are only 2 hours of recording time.

In one airplane disaster documentary, the CVR started recording at the gate and when the plane was getting de-iced.

So when does a CVR start recording, is this something that is started manually?


texts: How does wind affect takeoff weight limits?

texts:
Two days ago I took off from BUR in relatively windy (although dry) conditions. Flightradar showed departure from runway 33, and winds were recorded roughly mid 20s kts from the N-NNE direction. Temperature was mild at mid-60s. The aircraft was a B739.

Prior to door closure, after everyone had been seated, the captain asked for two volunteers to take a different flight. His reasoning as explained to us involved a combination of the windy conditions and the length of the plane (not stated exactly as such, but in a nutshell involved these two factors). The crew did not specify a section of the aircraft that the volunteers needed to be from, nor did they reshuffle passengers after two volunteers left. It was a nearly full flight, but not overbooked as everyone was already seated.

My confusion is why a plane taking off into strong headwinds would require less weight, when headwinds theoretically reduce runway takeoff length requirements and make takeoff easier, generally speaking. Because the captain mentioned the length of the plane as a factor, and knowing that the 739 has some more significant tailstrike risks, my hypothesis is that the nose pitch and/or flap setting in windy conditions has something to do with it, but I can't fully understand why. Can anyone explain why two passengers needed to be removed?


texts: How works the system of frequency for aircraft commercial Airline

texts:
Hello  I have to present a weather radar technology but i m block on  Air convention of communication.

I need to know how they exactly attribute licence to an aircraft and how all this aircraft can communicate without create collision between their communication .

Question one : Who attribute frequency for an Aicraft and how ?
- How are they attribute telecommunication frequency for commercial Aircraft .Each time they do a new fly someone give them a new frequency band ? They have a frequency band  for a specif numbers of fly ( E.g after 10 fly ) ?

Which authority give frequency band each countries ? but that mean if it's not a international authority you can use the frequency band only in this countries
Which authority decide into international zone what frequency band do you use ?

Question two : To much aircraft for number of channel
You have more than 20 000 aircraft use in the world however  I read you have 118–136.975 MHz Airband and only  potentially permitting 2,280 channels
so that mean a channel is use by more than one aircraft so what happen if two commercial aircraft have to use the same range of frequencies how their is not interference ?

My source :
 (https://en.wikipedia.org/wiki/Airband )
http://www.caa.co.uk/Commercial-industry/Airspace/Communication-navigation-and-surveillance/Radio-licensing/Radio-licence-categories/

Thanks you in advance for your supports.
Best regards,
CANAL Bastien


texts: Is there a good reason to have a handheld Aviation Microphone in GA?

texts: I have a Cessna 172P in which the handheld microphone has stopped working. Before I replace, I was wondering if there is any good reason to even have one? I have PTTs on both the pilot and copilot, yoke.


texts: What are pro/cons of steam as lifting gas for airships?

texts:
I was reading Wikipedia page about hot air airship and another Wikipedia page about the first powered and steerable airship which was powered by a steam engine. So I ask myself "why didn't they use the exhaust steam from the steam engine as lifting gas?"
After quick research, I found this home made experiment of steam used as the lifting gas. This website even gives a comparison with other lifting gasses:

+-------------+----------+------------+-----------------+--------------------+--------+-----------+-------------------+------------------+
|     GAS     |   M.W.   | Temp. (°C) | Density (kg/m3) | Lift (N/m3) in ISA | Safety |   Cost    | Ease of provision | Buoyancy control |
+-------------+----------+------------+-----------------+--------------------+--------+-----------+-------------------+------------------+
| H2          | 2        | 15         | 0.084           | 11.19              | bad    | fair      | fair              | no               |
| He          | 4        | 15         | 0.169           | 10.36              | good   | very high | very bad          | no               |
| CH4         | 16       | 15         | 0.676           | 5.39               | bad    | low       | fair              | no               |
| NH3         | 17       | 15         | 0.718           | 4.97               | fair   | low       | fair              | no               |
| hot air     | 29 (avg) | 110  (avg) | 0.921 (avg)     | 2.98 (avg)         | good   | very low  | good              | yes              |
| steam (H2O) | 18       | 100        | 0.587           | 6.26               | good   | very low  | good              | yes              |
+-------------+----------+------------+-----------------+--------------------+--------+-----------+-------------------+------------------+

(source: http://flyingkettle.com/jbfa.htm)
Given the conclusion of this website, steam should now be more widely used as a lifting gas:

it is available since the first lighter-than-air (plenty of time to develop the technology)
it has a good lifting power
it is cheap and safe

Yet, on 2020, almost all airships and balloons use helium or hot air, and no other lifting gas. So there must be drawbacks I fail to imagine. I hope finding those drawback will orient my research for my first question ("why didn't they use exhaust steam as lifting gas on airship fitted with steam engines?"). Moreover, there may be advantages I also fail to imagine.
Thus, what are pro and cons of using steam as a lifting gas?


texts: Why does this shockwave not touch the body that creates it?

texts:
In the shock wave of the next image (in a blunt body)

Why the wavefront is in front of the object? It does not assume that if the object travels faster than the speed of sound wave front should be just touching the object that causes it ?


texts: What would be the process to approve a minimal, standardized flight recorder for commercial balloons?

texts:
According to this article about the recent balloon event, the NSTB will try to interrogate personal electronic devices for any related data. Since some of these mentioned in the briefing do not contain cameras, they may look for accelerometer, gyro, and altimeter data that may have been captured automatically. Chips for these are commonly found in cell phones, tablets and other personal monitoring devices.

Standardization, performance and reliability are only some of the things that a NTSB-recognized voluntary flight recording device would need. Is there any mechanism or regulatory pathway for a standardized yet voluntary flight recorder for balloons, or would it have to be all-or-nothing - required, regulated, and therefore in the end substantially more expensive?

According to this recent WSJ article:

  More than two years ago, the NTSB urged tighter regulation of balloons carrying passengers. Without such changes, the safety board said in a April 7, 2014, letter, “the potential for a high number of fatalities in a single air tour balloon accident is of particular concern.”

Currently, passenger balloons do not file flight plans (see this question and associated answers), and while transponders for balloons may exist they are not required, nor is any passive reflection enhancement for radar.


texts: The F-16s that were scrambled to intercept United 93 did not have time to arm the jets, so the pilots were going to “ram it” how does that work?

texts:
The Wikipedia page says

Two F-16 fighter pilots from the 121st Fighter Squadron of the D.C. Air National Guard, Marc Sasseville and Heather "Lucky" Penney, were scrambled and ordered to intercept Flight 93. The pilots intended to ram it since they did not have time to arm the jets; this was in the days before armed jets stood ready to take off at a moment's notice to protect the capital's airspace.[140] They never reached Flight 93 and did not learn of its crash until hours afterwards.[141]

Is this exactly what I think it means? Crashing into another aircraft? What I’m picturing is the fighter pilots coming in above and behind, and using the nose of their aircraft in either a downward or upward motion to eradicate the stabilizer and elevator completely.
Any info is greatly appreciated!


texts: What is the definition of flow angle of a blade?

texts: I am confusing what is the flow angle of a blade with the angle of attack of a blade, so I was wondering if it was the same?


texts: Where can I find the regulations on the minimum stall speed for a GA aircraft?

texts:
I am designing a new GA aircraft that will enter service in 2028. I am looking for the FARS specifying the required minimum stall speed but different sources seem to say different things. On Cornell's Law school website, the Vstall is specified in 23.49. I found the same info on another site.

However, when I check eCFR, 23.49 doesn't exist. In fact, the regulations seem to end at 23.262. Were these other regulations amended or deleted? Which source should I use?


texts: What is the difference between a vertical stabilizer and a rudder?

texts:
I saw two questions on locating these surfaces ahead of CG:

Vertical Stabilizer and Rudder

How are these the same or different control surfaces?


texts: With respect to mid-air collisions, how is a near miss calculated, detected, and reported?  Does ATC have radar detection, or is it strictly up to pilots to report a close encounter with another aircraft?


texts: What are the differences between a GPS coupled autopilot and a GPSS autopilot?

texts: I'm trying to understand the differences here between an autopilot that is "coupled" into a GPS/NavCom like a Garmin 530W and what GPSS and altitude hold (like in an S-TEC 50 autopilot) have to do with this. Can anyone explain this to me? Maybe there is no difference, I really need this explained.


texts: How much extra weight is added by strengthening a piston-prop fighter for carrier landings?

texts:
To land on a carrier, an aircraft must be strong enough to withstand sudden deceleration by the tail hook catching the arresting wire. I think it also requires strengthening the undercarriage to survive a harder "plop" on landing.

So I would like to know, how much extra weight is added due to both of these things?

I'm interested in the WW2-era piston props. The modern jet fighters are much heaver, so I'd rather save that for a later question.

Ideally, the greatest example would be a piston-prop from this era made in two versions: land and naval. Then we could just compare loaded weights. But I can't think of any. Don't think I've ever heard of that. All of the carrier-based aircraft from WW2 that I know of, were purpose built for carriers and never had a land version. Hopefully someone knows where to find airframe specs for these aircraft and has the engineering know-how to say how much steel would be unnecessary for a land version.


texts: Where can I find accurate information about fuel efficiency of Airbus vs. Boeing planes?

texts:
I am trying to understand the competitive positions of Airbus and Boeing's large civil aircrafts. I would imagine fuel efficiency would be very important to airline given its large component in the total costs of operating. Where can I get information on the fuel efficiency of the large major planes e.g. A320 vs 737 etc?

Thank you


texts: What are the different types of procedures for starting a fuel injected engine?

texts:
Can someone explain the various types of procedures to start a fuel injected piston engine? What is a cold start, hot start, etc.?

I'm referring to a GA aircraft.


texts: How do groundspeed and IAS change during eights on pylons, and how should I manage them?

texts:
When performing eights on pylons I know that groundspeed (GS) reduces as we fly into the wind and increases as we fly with (or away from) the wind. This is the direct cause for the need to constantly change altitude (PA).

My question is in two parts:

As I descend into the headwind, why does my indicated airspeed (IAS) increase while my GS is reducing (and vice versa when flying with tailwind)? I have made a chart that shows XX GS = XX PA. When I look at my actual GS, I then look at my chart and find that I am at the correct PA for that GS but my IAS seems to spike in the descent and plummet in the climb.
Should I use the throttle to hold my IAS as it was in the entry?


texts: Can I execute an ILS approach using a NAV CDI with LOC signal only?

texts:
I have been flying a small Cessna airplane that has a COM/NAV NARCO MK12 equipment with CDI (lateral needle only).

This CDI does not incorporate a horizontal needle to provide vertical guidance, so there is no glide-slope indication for ILS.

Last time I tuned the LOC frequency of an ILS procedure and the CDI captured the LOC signal. The audio panel also captured the O M I markers.

My question is if it is legal to execute an ILS approach "with LOC" only limitations, as published in the approach plate (since the airplane does not have any GS information).


texts: How do the fighter jets in air shows color their smoke trails?

texts: At some large military parades or airshows, there will be tiers of fighters arranged neatly. In order to increase the visual effect, white or colored smoke will be sprayed from the tail of the fighters. How is color added to the smoke?


texts: Why does an aircraft leave a white smoke trail?


texts: Airline flight scheduling method differences

texts:
What are the differences between American major mainline passenger airline scheduling policies?

Presumably, each airline runs a model or optimization problem for determining

where (markets/airports),
when (timing of the flights throughout the day), and
how many seats (plane capacity).

Are there any specific examples of different scheduling policies, methods, or algorithms among airlines - within the context of each airline doing the best it can to match its schedule to market demand, according to its business plan and strategy?


texts: Did the XF-84H Thunderscreech really cause "900 sonic booms per minute"?

texts:
The Republic XF-84H, known as the "Thunderscreech" was an experimental version of the F-84F Thunderstreak. It was intended to be a supersonic turboprop fighter.  Even at idle, the prop tips rotated at supersonic speeds and the plane is often claimed to be the loudest ever built, supposedly audible 25 miles away.

Most sources describe a continuous sonic boom due to the supersonic prop tips. However, a fairly common claim on the internet is that they caused "900 sonic booms per minute."

Is there any truth to the claim that the plane caused 900 sonic booms per minute?

One's first thought should be, "no": because the prop tips are continuously above the speed of sound, they emit a continuous sonic boom (as most sources claim), not 900 separate ones per minute.  However, since the prop tips were supersonic and the roots were not, it follows that a section of the prop's length would be in the transonic range. Any change to the wind or propeller RPM would cause more or less of the propeller to be moving supersonically.  I suppose that, say, an appropriate oscillation in the turbine engine could cause the continuous boom to be modulated by some 15Hz (900-per-minute) component.


texts: What use was there for Boeing to include customer numbers in their aircraft model names, and why did they end this practice?

texts:
Inspired by this question (thanks Hot Network Questions!).
The tl;dr is that Boeing included a unique numeric model number designation, referring to the customer that had purchased a particular plane, in the actual model number of the plane. For example, a 747-8 for Lufthansa would be reflected as "747-830", where 30 is Lufthansa's unique customer number.
What is the utility of this "customer model number"? I assume it was used downstream by e.g. fitters and painters to determine what specific customisations should be applied to the airframe, but it seems that since 2016 this practice has been phased out.
Does anyone happen to know the history behind these numbers, i.e. how and why they came into being and why Boeing chose to stop using them after literally decades?


texts: How could a light or buzzer on the ground be triggered from an aircraft?

texts: I work at a Skydiving company in New Zealand and we are looking for a light switch or buzzer that is triggered in the plane and can effectively alert the staff on the ground that the plane is 3 minutes away from dropping the Parachutes. The plane can not have any external alterations and the device has to be completely portable, we currently have a small wifi router inside the plane but it is very unreliable. I'm completely oblivious to the world of electrical engineering so any help would be greatly appreciated


texts:
Are there any systems in a manned aircraft which can be controlled by the ATC/ground control.

To be specific, could you name some tested and existing procedures/systems which make it possible to change aircraft dynamics such that it is manipulated from outside the cockpit of the aircraft and the pilot is overridden?


texts: What are the roles of the co-pilot in commercial aviation?

texts: I am currently doing a project(in college) on the history and future of the role of a co-pilot and to start it off I wanted to just summarize what the roles of the co-pilot are.


texts: Is it required for pilots to contact ATC while flying VFR?

texts:
Does a pilot need to communicate with ATC while flying VFR (during departure, flight or departure) or does it depend on type of flight (like private, commercial, etc.)?
Or is it required for pilot to inform ATC only during arrival and departure for runway clearance and altitudes?
If a pilot does not remain in contact with ATC during the flight, how does ATC know what pilot's intentions are?


texts: How will the update from DO-260A to DO-260B improve safety and efficiency in air traffic management significantly?

texts:
From what I know, the version update from DO-260A and DO-260B offers new features such as on-ground vs airborne source selection logic, ADS-B failure annunciation, the split of the quality indicators between horizontal and vertical component, the addition of GVA and SDA, etc. In comparison with the previous versions, it is expected that the latest version could at least increase efficiency and safety in utilizing airspace.
Assuming country “X” has implemented DO-260A as their minimum standards for its surveillance infrastructure and it could accommodate up to 1000 planes every hour. Then it decided to update to DO-260B and could accommodate up to 2000 planes every hour.  And yet I ponder with all of these new advancements in DO-260B, is there:

A way that I can estimate and measure quantitatively based on the update? (Assuming that DO-260B does improve safety and efficiency in air traffic management)
With the quality indicators in DO-260B, how are those used in the process of that estimation?
A website that analyzes safety and efficiency quantitatively on air traffic management, specifically after changing MOPS such as from DO-260A to DO-260B ?
 Thank you in advance.

Source:
1. https://atl.aero/wp-content/uploads/2019/01/ADS-B-Out-Instalaltion.pdf
2. RTCA DO-260B DRAFT Version 4.2


texts: What aircraft would have these tail numbers?

texts: Last night I was looking at a flight radar on my phone, and I saw two blips flying close to each other over Camden, NJ. They were heading northeast at around 250 knots, and the only information displayed was their registrations, listed as 1678c37 and 1678c38. A google search of these displayed no results. Are these military or other special aircraft?


texts: How accurate is CFD software compared to wind tunnel tests?

texts:
How accurate is computational fluid dynamics (CFD) software compared to wind tunnel tests?
(I mean CFD computed with super-computers like the aircraft industry has.)


texts: It sits in a very large backyard in Lancaster, California.


texts: How do big planes like 737 manage fresh air for passengers during flight?

texts:
How do the big planes (e.g. A380 or 737) flying on high altitudes manage to get fresh air for passengers and crew during the flight?

I know the inner space of the plane used for passengers and crew is sealed and the pressure is maintained within some range.

However in standard flight altitude of about 10-14 km there is not enough oxygen to breathe.  I am not sure whether the standard oxygen ratio is still about 21% and you only have less air (lower pressure).

We talked two possible solutions and maybe I am still wrong:

using some pumps and small pressure tanks to suck in air from outside till we get higher pressure and then use some valves to "replace" the breathed up air with the fresh one
use some pressure tanks loaded with oxygen + some cleaning devices to clean the air and add oxygen to keep the same oxygen level - but this would need to get the oxygen before take-off and such tanks would be really dangerous

So how is it in reality?


texts: Do aircraft manufacturers have the authority to either approve or disapprove the maintenance procedures of its customers?

texts:
Having currently read this article in Wikipedia, linked through Reddit, regarding American Airlines Flight 191, which crashed due to maintenance issues.

Inside the article, it says

  McDonnell-Douglas, however, "does not have the authority to either
  approve or disapprove the maintenance procedures of its customers."

Is that the scenario in the current aviation industry, or has it changed. Why would airline companies not listen to the manufacturer and carry out non-approved procedures.


texts: Where does the 35 feet screen height come from?

texts: When taking off, why are we required to climb at least 35 feet over the departure end of runway? Why not other numbers? This comes from the FAA regulations. I believe there must a clear explanation for this but can't find one. Is there any historical or mathematical reason?


texts: Can a simulator (FFS) be used in place of a Technically Advanced Aircraft (TAA) to meet the commercial experience requirements?

texts:
14 CFR 61.129(a)(3)(ii) lists the aeronautical experience requirements for a commercial certificate. It says:

  (ii) 10 hours of training in a complex airplane, a turbine-powered
  airplane, or a technically advanced airplane (TAA) that meets the
  requirements of paragraph (j) of this section, or any combination
  thereof. The airplane must be appropriate to land or sea for the
  rating sought;

With the changes to this regulation to allow TAAs, does the FAA allow simulator (FFS) hours in place of the TAA hours?


texts: Why is AVGAS so much more expensive than car gas?

texts:
Why is 100LL so much more expensive than gasoline for cars?

I get the fact that it's 100LL, instead of 87, 91, etc.

For example (as of now, 13 Oct 14), the 91 unleaded gas at my local gas station is 3.41USD, and the 100LL at my local airport is 5.49USD (for the self serve).

What's the reason for the huge increase in price between car and aviation gas?


texts: Is it incorrect to refer to a C-130 as a jet?

texts:
In this article by CNN, the C-130 involved in the unfortunate crash in Savannah, GA is referred to as a "jet." Is this considered proper usage? I'm not looking for public opinion here but official categorization, if one exists. Perhaps there is an USAF or FAA document I've not been able to find which delineates such things. I would imagine that there is also an engineering or academic definition of such things.

The AV.SE description of the Turboprop tag states that it should be considered "as opposed to a jet engine."

Wikipedia says that "Turboprop engines are jet engine derivatives." which really sort of muddies things but the actual turboprop article notes that "the exhaust jet typically produces around or less than 10% of the total thrust" It never occurred to me that the thrust produced by a turboprop engine is even measurable. Would this factor, then, be the delineation between jet and prop? Should it be a matter of whether the exhaust gasses or rotating components propel the aircraft?

So to restate my question, Should a C-130 be called a jet even though a significant percentage of its propulsion is derived from a propeller?

Note: Please consider JATO/RATO outside of scope of this question.


texts: At https://www.aviationweather.gov on the Forecasts puldown, then the Aviation Forecasts selection, the chart opens and often shows what looks like a letter R with a tail in the lower right, in different colors.  The legend does show the symbol. What does it indicate?


texts:
I pretty much understand the way a wing works and the different ways of explaining it, what I don´t understand is why the lift on a subsonic wing manifest itself at the 25% chord....

The 50% chord would seem more logical if You ask me....

If I was told that the lift IS NOT at the 50% chord and were told to make an (uneducated...;- ) guess as to where it then would be, I would probably guess at the 75% chord rather than the 25%....

As a plane like the Dash 7 which has VERY efficient flaps has its nose pressed down if the flaps are deployed at too high a speed, or, as a wing-shaped leaf would turn nose down at first....

I understand that the lift manifests itself at the 25% chord, I just haven't got a clue as to WHY....???

I just asked a kind of similar question about the lift-shift that occurs at supersonic speeds. I was thinking of asking this question together with that, but I guess it's more of a question of its own....


texts: Is the word “bomb” muted in inflight movies?

texts:
I was recently on a transatlantic flight and watched the movie Steve Jobs on the plane’s entertainment system. Every movie I tried, including that one, had a message right at the start saying the movie had been edited for content.

In one scene, the caracter of Steve Wozniak is fiddling with a watch and the character of Steve Jobs makes a joke it looks like he’s messing with a bomb. Those words were muted. The word “bomb” (and one or two words around it) were gone from the movie. I even rewinded to make sure, and the words were indeed gone.

Is there some weird law that forbids the use of the word in inflight entertainment systems? It there is, it’d be particularly weird since you need to plug headphones to listen to the movie in the first place, so it’s unlikely you’d cause hysteria. In addition, the word was pronounced again later on in the movie but wasn’t muted then. It was less clear audibly, though, so it’s feasible it wouldn’t have been caught by the automated system (if any is used).

The airline was TAP, and the entertainment systems are individual per seat.


texts: What happens on the engine after ingesting volcanic ash? Is volcanic ash dangerous for the cockpit crew too? Despite the ground stations, is there any other way to identify volcanic ash while flying?


texts: Double deck vs wide body airliner, why would anyone build a double deck one?

texts:
I don't understand why double deck aircraft (or multiple decks in general) are a good idea. They must be, because there is a significant amount of them.

But given a cross area, which should roughly correlate to the drag of the body, wouldn't a wider cross area provide some additional lift for "free" as compared to having higher lift wings instead?

Why don't we see very wide airliners where the body provides a siginificant amount of lift?


texts: If Boeing used two sensors instead of one simultaneously, wouldn’t they be in the same position today?

texts:
this article states  that the original version of MCAS was suppose to rely on two sensors,

One sensor will detect a high angle of attack, therefore activating MCAS
The other sensor will detect a high G force and therefore activate MCAS.

But what I don’t understand, is why people use this as an argument against Boeing, as if they should have went with that idea? If the high g force sensor was faulty, wouldn’t it technically need a second sensor looking at a high g force, in order to compare the two?
So basically if they had stuck with that idea, we’d still be here today?


texts: Have landing gear collapsed at the gate?

texts:
Reading an answer to this question piqued my curiosity. Has there ever been an instance of an airliner's landing gear collapsing while loading/unloading passengers?

I do not include after emergency landings, but just while "sitting at the gate."


texts: Are there US guidelines on how aviation is handled during an emergency situation?

texts:
Suppose that we find that a meteor is headed for, say, Dallas, TX, and it's too late to prevent the impact. The USA has 3 days to evacuate the area before the impact. The impact is one of the size of Tunguska: it will inflict massive damage in an area about the size of London, and we will notice the impact, but it will be mostly localized damage, so there's no global climate change or widespread damage.

Naturally, if you need to evacuate 1.26 million people in 3 days, you want to speed up the evacuation as much as possible, so you want to use all the possible methods of evacuation, be it through air, on water or on the ground, as efficient as possible.

Is there an American Federal authority like FEMA, the TSA or the FAA that has guidelines on how to handle the aviation part of such an emergency evacuation? The example of a meteorite is just that, an example. The meteor itself is not that relevant, what is relevant is how they'd handle the aviation part of the evacuation.

To clarify: I'm specifically talking about the aviation related parts, so anything related to the airspace over the area, how it would affect regional passenger traffic, to what extent local airports and pilots would be involved,... I realize there are other related actions, like evacuations through the highway and route system and through waterways and canals. Those are not what I'm interested in, insofar as they're not related to air traffic and aviation.


texts: Why did this departure from Buenos Aires seem to delay heading northeast?

texts:
It was going from Argentina to Germany and after takeoff it went over a town and then it went direct to Germany. Why did it go over the town instead of going directly to Germany?

Source


texts: How do pilots/controllers deal with overlapping transmissions on the radio?

texts:
A disadvantage of the analogue radio1 used for communication is that it does not receive when it transmits. Everybody is trained to wait until the frequency is quiet before starting to talk, but it's still possible that two stations will start talking at the same time, in which case everybody else will hear an unintelligible mess but the two talking will not be aware of it. The station who talks longer won't be aware at all and if they talk for similar time, neither may be aware.

What I would like to know is how humans deal with the problem and whether there is any specific guideline for resolving these conflicts.
It seems like if the controller just says "calling centre, say again" the two may just both start talking past each other again.

1 Just like any other shared frequency radio, but digital systems seem to have more options to handle it, especially for the relatively low bandwidth requirement of voice communication.


texts: How would the FAA catch people without licenses?

texts: It is know that the FAA conducts ramp checks at airports. However, is it likely to be caught flying without a license from uncontrolled airports or grass strips? If so, how would one be caught?


texts: Why do flight attendants wear gloves during takeoff and landing?

texts:
Last time I was flying the flight attendant put on black leather gloves during while she was seated during takeoff and landing. She took them of as soon as she got up from the seat.

This wasn't the first time I've seen this.

Is this a safety of flight issue?

Edit:
The airline I've seen this was Finnair.
There where three flight attendants on the flight, but only one was sitting near me, so I couldn't see what the others did.


texts: What trade-offs are being made in the design of the planform alignment of stealth aircraft?

texts:
Stealth technology uses angles in the aircraft shape, and homogeneous orientation of the surfaces. In the F-22A Raptor wing leading edges, tail surfaces, air intake bypass doors, refueling aperture, etc have the same orientation.

Incoming radar waves are deflected in a different direction, giving the enemy the impression that there is nothing there.

However, as mentionned in Wikipedia: "Shaping requirements detract greatly from an aircraft's aerodynamic properties. The F-117 has poor aerodynamics, is inherently unstable, and cannot be flown without a fly-by-wire control system."

I'd like to know what are the impacts of such planform alignment on planes capabilities, and how does a passive stealth shaping, using a small number of surface angles, compare to a "5th generation fighter"

This is a different question than Do similar angles on a plane make it more stealthy?" I'm looking for the advantages and disadvantages of using planform alignment.


texts: Do vortex generators increase Re of a wing?

texts:
Do vortex generators (VGs) increase Re of a wing?

I understand that VGs re-energize the boundary layer on a wing.

I understand it turns laminar flow into attached turbulent flow.
Doesn't that mean the Re increases substantially?

If so, wouldn't that increase it's cl/cd, which means lower drag in the 600-900k Re range?


texts: Where can I find a navigation database for Brisbane?

texts:
Does anyone know of a database that details the GPS locations of beacons within Brisbane; or a data-set that tells me air routes and associated en-route beacons, way points etc.?

I'd like to be able to plot a course on a map (Google, Bing, etc) from A to B given an air route or flight plan. SkyVector looks very similar to what I'm trying to achieve.


texts: What phenomenon causes aerodynamic tail-down force? Why will there be more downforce on the tail when an aircraft picks up speed? What happens if the aircraft goes too slow - does this means less downforce on the tail? Do the center of lift and center of gravity play any part in determining the downforce on the tail?


texts: Is it possible to go-around at Lukla Airport?

texts: On this airport, it seems the runway end with a wall followed by a mountains. Thus the pilots physically can't overrun the runway and if they decide to interrupt the landing, the go-around maneuver seems to include a very tight turn to avoid the mountain unless performed very soon during the approach. Is it possible to perform a go-around, and a which point it becomes impossible for this particular airport?


texts: Why are clearing turns supposed to be shallow bank?

texts:
During my CFI training, my instructor relayed a story in which he had a mid-air collision while teaching (how to teach) clearing turns to two other CFI applicants. The other aircraft was underneath them and may have climbed into them. No one in his aircraft saw the other aircraft. They did not even know they had hit another aircraft until they heard the report of another crash nearby.
My question is (in the title) why is a shallow banked clearing turn considered better than a steep one? I feel like I get a much better view of everything (above, level, and below) in the direction of the turn if it is a steeper turn. The downside is that I'm changing direction more quickly...but I think seeing other aircraft wins over that. Furthermore, large, rocking wing movements tend to make the aircraft I am in easier to see as opposed to gentle, shallow turns.


texts: Why are wings load tested by putting weights on the underside of the  wing (placed upside down)? A wing is being pulled into the air from its upper surface in flight, so shouldn't it be load tested in the other direction?


texts: How can a flying wing style airplane recover from a spin without a vertical stabilizer?

texts:
I fly a Cessna C-172, and if I have any bank when stalling, I have to use rudder to level the airplane. If I use aileron, the bank angle will increase and bring the airplane into a spin.

My question is, if there is no rudder or vertical stabilizer, like a B-2 bomber for example, how could a plane recover from a stall?

This question is different from others because this is not focus on the stability or control of 6 freedom. I would like more discussion on the recovery of spin and stall.


texts:
My instructor told me that courtesies are forbidden in radio communication, however, we usually start conversation as "Turany Ground, OK-ABC, good morning, (... request)".

I find it natural. Is that acceptable violation of the rules, or could it cause some troubles?


texts: If the previous 100 hour was overflown but not for hire, is the time still subtracted from the next 100 hour?

texts:
A rental plane at a local FBO had an annual inspection at 2345 hours on the Hobbs. The next 100 hour inspection wasn't completed until 2450.

If the current hobbs time shows 2547, would it be legal to take the airplane for a 2 hour flight lesson with an instructor?

Also, does the legality of this situation change depending on whether the 5 hours between 2445 and 2450 was with an instructor or not?


texts: What is the oldest aircraft still in production? I Googled it but only got the answer to the oldest military aircraft still in production.


texts: How do pilots know that the switch/knob they just switched on/off actually did what it's supposed to do?

texts:
With the plethora of switches/knobs/buttons etc present in airplane cockpits, how can pilots be really sure that a button they just pushed (either to enable/disable some electronic system or move some non-visible part of the plane for example) has actually done its job correctly?

Is there some sort of visual or auditory feedback?

Or do they have to always assume that these have worked, until they realize otherwise by observing the airplane or other related systems behavior?


texts: Has this "straight through" airport design ever been contemplated?

texts:
Here's an airport, with some planes on the various runways/taxiways and some using the terminal ..

(airliners in green)

Airport/terminal design is really tricky.

There are many spatial problems which are unsolved, resulting in the incredibly inconvenient (for humans/planes) current airport paradigm.

Has an "over" terminal ever been contemplated?

terminal indicated in blue

So, the (whole) airport terminal building is simply up on stilts.

(Obviously, the clearance is high enough for the tallest existing and forseeable airliners.)

At a stroke this utterly solves two problems:

Airliners never again need to reverse.  They just land, drive around anywhere they want, stop under the terminal.  Passengers get on and off.  The airliner drives off again, drives to a runway (perhaps again passing under the terminal - no issue) and flies off.

No craft would ever reverse.

This would be a complete paradigm shift, slashing handling times, costs,  personnel, machinery.

The fundamental spatial problem of airports is solved at a stroke: You can land or take off anywhere, and get to and from, any gate.  (Sure, you have to avoid the few pillars holding up the terminal.)
From the human crowd movement viewpoint, the need for the hell of "separate terminals" is slashed or even eliminated. At worst you'd just have two or three "ranks" of these (rather like giant rows of car parking in a parking lot).

Again this would spectacularly slash the size and infrastructure costs of airport concept design. Often the whole concept of ridiculous people movers, monorails etc would be eliminated or slashed.

Note that the car freeway system would just connect to the end(s) of the terminal building. (Indeed, as usual.)

(But indeed, perhaps the blue structure could indeed include "the road itself". So the blue object represents both car driving lanes and the terminal structure, shopping, etc.)

On that: looking ahead, it's possible there could finally be a drive to your actual gate concept (if check-in / baggage handling / border functions could be rationalized), which would be an total paradigm shift in air travel.

The only technical difficulty is AeroTech or whoever would have to make a jetway that comes "down"...

Note that it's obviously trivial to make huge civil structures "elevated",

(Indeed a civil structure for foot traffic, shops, etc is (I believe) a lighter load than a super-freeway or bridge,

)

Ideally the supporting piers would be infrequent, allowing for totally free and easy movement of airliners, but even if the columns were between each "bay" the major paradigm shifts are achieved.

This airport paradigm would seem to be staggeringly more efficient than the current paradigm.  No reversing ever!  Free driving anywhere for all craft over the entire area.  Wasted space slashed.

Has this ever been contemplated?


texts:
I understand the B737-800 has two air conditioning packs that handle the temperature of three zones: the cockpit, the fwd cabin and the aft cabin.

I understand that which pack is turned on is controled from the cockpit.

My questions are:

can the temperature be regulated for each zone seperately?
where are the switches located that control the temperature in each zone?
who operates these switches?


texts: Does the main helicopter rotor blade shape affect noise?

texts: Most blades are squared off at the end. The Cobra fighting ship has pointed tips. Does this cancel out the "wop wop" noise? The reason I ask is that today I saw the Cobra in this news article. The tips are pointed. In 1968 I worked at Bell Aerospace making blades for use on Hueys and all had squared off tips as were tail rotors. Seeing this bird brought back memories.


texts: What are the mass flow rate and exhaust velocity for a CF6 or GE90 turbofan?

texts:
For a typical turbofan jet engine (two examples given in the title), what is the exhaust velocity and mass flow rate of air at sea level and cruising altitude (~ FL350)?

Also, does the specific impulse vary at different altitudes, since the density of air decreases with increases in altitude?


texts: Can I get a pilot's license if my driver's license has been suspended?

texts: My driver's license is suspended because I got a bunch of tickets. It was the first time and I've paid the tickets. Can I still go for a private pilot's license?


texts: What portion of an Instrument Proficiency Check must be in the airplane?

texts: I was asked this question by the Chief Instructor at my Part 141 school. I've looked all over and I can't seem to find an answer to this question. We often use the AATD which is a Redbird full motion but I've not heard anything about a specific portion being in the airplane whether or not you did it all in a sim, or a mixture of simulator and airplane. Can anyone elaborate on this? Thank you in advance.


texts: Is the airspace at KGPT class E or G when the tower is closed?

texts:
I'm a bit new to airspace and I'm trying to figure out if the airspace around Gulfport-Biloxi International (KGPT) changes to class G or E when the tower closes.  Looking at KGPT's airspace on a sectional, it is Class D with a note to check NOTAMs/Supplement for Class D/E (sfc) effective hrs.

I've checked the chart supplements and it says Class G when the tower is closed, but the AIM leads me to think it would be Class E at 700' MSL (with Class E extensions changing to Class G) when the tower is closed since it has ASOS.  Does this sound right, or am I missing something?


texts: How are pushbacks coordinated between the pilot and the tug?

texts:
When the pilot (PIC) of a large jet is cleared for pushback and start, how does he signal the tug to start towing the aircraft, and where to go to?

The pilot has to monitor the ground frequency the whole time, so is there a second radio for talking to the tug crew? Or perhaps a wired link between the aircraft and the tug?

Does he just tell them to "take us to start point alpha" or whatever, or does he have to give more detailed instructions?

Are the tug crew listening in to the instructions from the tower?

If the aircraft has to stop unexpectedly (because of an instruction from the tower, or because the pilot has a safety concern), how is this coordinated safely?


texts: What is the minimum takeoff fuel requirement policy for commercial aircraft?

texts:
I am currently working on a fuel burn analysis of a particular route (ATL to DCA). I really want to predict takeoff weight of the flight; however, I realized that it's not easy to get the information. Instead, I may want to gather information about minimum fuel requirement for the flight.

For example, I heard from the pilot of the flight that they should have more fuel (20,000lbs) than the minimum fuel (15,000lbs) before takeoff. Could anyone please let me know where I can get this information such as minimum fuel requirement for A320 from ATL to DCA?


texts: What are the pros and cons of single-engine vs. twin-engine?

texts:
Why would someone prefer to own a single-engine vs. a twin-engine airplane?

What are the pros and cons of each?


texts: What problems can be encountered if an airplane does not undergo wind tunnel testing?

texts:
SpaceShipOne did not use any wind tunnel testing. According to the Scaled Composites FAQs:

  Q: Did you do wind tunnel testing?
  A: No. All design refinements and performance predictions have been derived from Computational Fluid Dynamic tools.

What problems would such an aircraft face (which is designed completely without wind tunnel testing)?


texts: Legal requirements for electronic flight bags like Foreflight or SkyDemon

texts:
I’m wondering what the legal requirements to use EFBs like ForeFlight or Skydemon or similar for primary flight planning and navigation. If I remember correctly, I once heard about requirements on battery percentage, backup device, external battery or similar.

In particular, I’m interested in the situation in Germany, but I’m happy to hear about differences to other countries (e.g. FAA vs. EASA) as well. I’d be happy about hints on where to find regulations like these as well.


texts: Can paragliders in the US communicate with ATC?

texts:
I am a private pilot looking to get into paragliding. After talking to some of my friends who do paragliding in the San Francisco Bay area and watching YouTube videos I noticed some fly through places like VPMIN (which is near SUNOL). That's an extremely busy intersection, sometimes right in the altitude ranges I normally fly through them in my powered aircraft. From this I had a few questions:

Is it possible to get the equivalent of flight following or at least call up ATC to let them know you are there, if you are planning on flying at higher altitudes? I am used to doing this for a D airspace if I am flying only just over or near it if they are not busy.
If so, what would the phrasing of that sound like when you don't have a callsign?
14 CFR 103.17 says that I require prior authorization to enter class B, C or D airspace. What does this look like? Can I take a handheld radio and ask for permission on the tower frequency? Or is this something I'd need to get through written permission from a FSDO or the tower directly?


texts: What does the A340's underwing bulge (plastron) look like?

texts:
From Wikipedia:

  From the start, engineers noticed that the wings were not stiff enough to carry the outboard engines at cruising speed without warping and fluttering. To alleviate this, an underwing bulge called a plastron was developed to correct airflow problems around the engine pylons.

The reference used is not online, and having checked many high resolution images, I can't seem to spot that bulge/device.

It's also not mentioned as far as I checked in Scott E. Germain's Airbus A340. But I found the following paragraph on page 15, which may be of relation:

  Attention also focused on drag reduction by achieving laminar flow across the wings, engine pylons, and structural intersections. This undisturbed flow requires perfectly smooth wings, aerodynamic surfaces, and fairings. Problems arise in the manufacturing process when surface irregularities lead to drag producing ridges and dimples in the surface of the aircraft. Airbus overcame these problems with automated component production, assembly line robots, and strict quality control measures.

Some of the photos I checked: here, here, here, here, and here.


texts: In general terms, is a Constant Speed Propellor equiped aircraft more expensive to maintain?

texts:
I've been looking at possibly buying a used Mooney M20 or a used Cessna 172.  One of the big differences between the two is that the Cessna is a fixed prop, and the Mooney is a constant speed propellor.  While CSPs sound really nifty and efficient...I can't help but wonder if they would be more expensive to maintain.  Both in terms of regular maintenance and just the fact that it has more parts that can break.

Is a CSP more expensive to maintain than a fixed pitch prop?  And why? If you can include some numbers that relate to the planes mentioned, that'd be cool too...


texts: What, if any, are the rules on ATC politeness?

texts:
There are plenty of recordings available of ATCs acting impolite, in the linked video, the pilot says he will file a report about the conduct of the ATC.

Would this actually result in any disciplinary action? What are the formal, contractual rules around tone, manners and general politeness when speaking to pilots?


texts: What were the historical safety statistics of airplanes?

texts:
There's lots of debates in the Space world about the safety margins of modern rockets (specifically the fact that the ITS isn't planned to have an abort mode as (in the words of many SpaceX supporters), it "should be as safe as airplanes").

Now, I know that modern airplanes are crazy safe (as in, the last fatal crash of a major US airline in the US was just a month after 9/11), but I presume that back in the 1920s seats on airplanes were sold commercially without passengers having an abort mode either, and those airplanes were much less reliable than modern ones.

How has the accident per flight statistics changed throughout aviation history?


texts: What is that instrument with two knobs and what looks like range rings?

texts: I just flew a Piper Warrior today and I got confused with the instrument shown below, it's the one above the CDI and to the right of the altimeter.


texts: Is this an accurate depiction of the internal shape of a turbofan engine?

texts:
This image (so commonly used here that the first image reference for it that pops up in a Google search for "jet engine diagram" points back to ASE!)

From Wikipedia

Shows the housing of the actual "jet" section very tightly packaged around the various sized compressor and turbine stages, leaving a diverging/converging path for the bypass airflow.

It seems to me that it would make more sense for the packaging of the inner jet engine to be a fairly even cylinder so the bypass air flows smoothly around it and out the back of the nacelle as I've attempted to depict with the blue line at the bottom, or a somewhat converging shape as I've depicted with the red line at the top.

Source: personal modification of above mentioned Wiki picture. Don't laugh... I drew that with my thumb-operated trackball.

However, as I've typed this question up and looked at the diagram more, I can see where the converging path around the low-pressure turbine section of the jet would add additional pressure to the bypass air and, therefore, additional energy to the escaping air.

Is this simply an "artist's concept" of a cross-section of a turbofan engine, or is it an accurate depiction of the internals?

Note: I do understand that within the jet section of the engine the shaping needs to be tightly packaged to ensure the jet-internal air flows exactly where it's needed, my question is about the flow of the bypass air only.


texts: How can the radar range for ATC be estimated based on stated maximum radar range?

texts:
Is there a way to estimate the maximum effective range of a naval radar for air traffic control functionality, based on the radar's stated overall max range?

For instance, if a naval radar that has targeting functionality states that it can detect artillery fire at a maximum range of 75NM, is there a way to estimate its range for air traffic control purposes (e.g., a max range of 75NM translates to about a max functional range of 25NM for air traffic control?