texts: Is there a relationship between transonic buffet magnitude and altitude?

texts: Transonic buffet happens at mach 0.95.  The correlated true airspeed varies with altitude.  Does the transonic buffet magnitude also vary with altitude, and if so, how?


texts: How is human waste taken care of on commerical aircraft?

texts:
Trains, as far as I'm aware, just dump human waste on to their own tracks. There are often warnings like: DO NOT USE the toilet while the train is stopped at the station voiced through the PAs or signed up on the walls. The Daily Mail, in 2014 had an article mentioning: Train companies are to be ordered to adapt their trains to stop dumping sewage on the tracks.

I always kind of assumed that commercial airliners did the same, but I've never heard any warnings about using the restrooms aside from when the seat-belt sign is on.

How do commercial airliners take care of human waste?


texts: Why does the Antonov AN-225 not have any winglets?

texts:
Winglets provide a lift boost that would be useful to a plane of this size. But the An-255 does not have any winglets.

Why is it so?


texts: What are the most efficient layouts of multiple runways?

texts:
Many airports have more than one runway. How should runways be built in order to achieve maximum usage and minimum delays?

Many major airports have most, if not all, parallel runways. Examples include LAX, DFW, and ATL.

In fact, Chicago O'Hare has been undergoing some major runway improvements, mainly to make the runways more parallel. This figure shows the before (mid-2000s) and after (completion date TBD) layout of ORD. Eventually, ORD is slated to have 6 parallel E-W runways, along with 2 SW-NE runways.

However, a crossing configuration is very common at airports with only 2 runways. Here is one example:

Are parallel runways more efficient, and smaller airports simply don't have space for them? Ideally, how should runways be configured?

Edit:

Additionally, what if we assume...

Case 1 - That wind isn't a factor?

Case 2 - That the airport location has exceptionally variable winds?

Case 3 - That space/airport footprint is an issue?


texts: Can an airplane engine fire be extinguished without shutting down the engine?

texts:
Airplane engines catch fire from time to time (and are falsely reported as being on fire even more often).  In a modern airliner, the "fire handle" shuts down the engine, closes the fuel pipe, and discharges the fire extinguisher.

Occasionally it's desirable to leave the burning engine running because you need the added thrust. For example during WWII B-29 engines had an unfortunate habit of catching fire on takeoff. Standard procedure was to leave the burning engine running until you got enough altitude to safely discard the bomb load and/or bail out.

Is it possible to activate the fire extinguisher without shutting down the engine?


texts:
Just was reading this manual => DLE-120 engine User Manual
On this page (pg 4), I saw this formulation:

What does it mean? How is the 30:1 ratio calculated? What does "fl oz" mean? What does "2-cycle oil" mean? Where are these number coming from?


texts: Can an automatic vane-based stabilizer really work?

texts:
Can the pitch stabilizer in the picture really work for a plane or glider?

The image shows an automatic pitch stabilizer (the mechanism in the black rectangle) that is based on the vane 50 whose movements up and down would drive, with the help of a force amplifier system, the horizontal front elevator of a Wright glider or plane in such a way as to maintain the aeroplane in horizontal flight.

More precisely if, for a reason or another, the plane have the tendency to dive there will appear a vertical component of the relative wind that will push the vane 50 upward and, through the mechanism already mentioned, the vane will drive the front rudder in such a way as to make the apparatus climb again. If the plane tend to rise, the vane will go down and command the front rudder to make the plane descend.

The question is, can this mechanism really work, at least theoretically? (A stabilizer based on a pendulum is a fallacy, it will not work. In an accelerated system (the plane) the pendulum does not align to the vertical).

Source: US patent No. 1075533 (filed by WRIGHT Co in 1908)

(I am not interested in answers regarding the automatic stabilizer in roll, also described in the patent. It is based on a pendulum and it can not work. My question is only about the pitch stabilizer.)

UPDATE:
My question has nothing to do with a pendulum stabilizer. The vane-based stabilizer (the subject of my question) works on a completely different principle. In consequence, the answers given to this question, that refer strictly to a pendulum stabilizer, do not help.


texts: According to ATFM terminology, when is a aircraft on the runway?

texts:
I am currently working trial writing a program capable of determining where a given aircraft is based on ATFM timestamps. My aviation background is pretty limited as I am only a mere IT developer.
When is an aircraft on the runway? Of course when it lands, and when it's about to take off, but there do not seem to be timestamps that indicate this?
Well the first one, the landing on to a runway seem to be covered by ALDT.
But when it's on the runway for taking off? ATOT? Is the aircraft not airborne at that point?
How do I using the ATFM timestamps determine when an aircraft is on the runway ready to take off?
Per a comment: AFTM is Air Traffic Flow Management, ALDT is aircraft landing time and ATOT is aircraft takeoff time.


texts: Do carrier-less militaries retain the equipment for carrier operations?

texts:
"How do jet fighters get to war?" made me wonder if aircraft used by the U.S. Navy and U.S. Marine Corps for carrier operations retain their carrier equipment when sold to foreign powers who do not operate carriers?

Pros would be the reduction in weight, repair/maintenance complexity, and cost (why bother paying for equipment you don't use?).

Cons would be engineering complexity (if they're not designed as optional components) or airworthiness (if the components have secondary functions beyond carrier operations).

The initial thought was prompted by a CATOBAR aircraft, but if something like the Harrier has different equipment, that would be relevant, too. What's the reality?


texts:
I read the absolute ceiling of an adequately powered airplane is determined by the formula,
$\frac{W}{S} = \frac{1.4}{2} p M^2 CL$
Where,
$W/S =$ Wing Loading
$M =$ Mach Number
$CL =$ Lift Coefficient
$p =$ Pressure
Could someone please provide the full derivation of this ?


texts: Can a four-engine aircraft with limited fuel gain extra range by shutting down one of its engines?

texts:
I was reading the book Vulcan 607 by Rowland White who examines the details of a British bomber's mission during the Falklands War in 1982. At some point, the author wrote about the fuel shortage experienced by the crew of the four-engine Vulcan bomber during their return to their base. The author wrote that the pilot "considered shutting down one of the four Rolls-Royce Conway engines to get a little more range out of the remaining fuel...".

I have not heard of this type of procedure before, so I am wondering if the decision to shut down one of the engines to maximize fuel efficiency makes sense.


texts: How many aircraft does an ATC controller usually handle at the same time?

texts:
My question relates to the question What is the maximum number of planes a controller can control?, which asks about the maximum limit. One comment indicated 35 aircraft per hour for en-route segment. I, however, are not interested in the maximum number of aircraft per sector, but in the typical number of aircraft.

I am now interested in the typical amount of aircraft per enroute Air Traffic Controller at any given time during the day (how many aircraft are handled at the same time by an en-route controller).

While I am sure that there is no universal ground truth, can anyone report experience? To limit the scope, let's assume continental U.S. or Europe during the day, upper airspace.


texts: Sometimes fixes found on approach plates are labeled radar. What are these radar fixes and how to they differ from fixes usually found on approaches?


texts: What is the minimal landing area required for an EC135 air medical services helicopter?

texts: The Netherlands has a few Eurocopter EC135s for air medical services. (See Wikipedia.) How much clear landing space is required (either theoretically, practically or regulatory) for these?


texts: What is the En-Route Information Display system (ERIDS) used for?

texts:
ERIDS is an information display system used at Air Route Traffic Control Centers. It provides electronic access to things like NOTAMs and static documents that previously were only available in paper. It was Implemented around 2006.

I get that it provides a bunch of general information and NOTAMs and PIREPs and such, but who uses ERIDS to access that? I know controllers have their own display, and I was under the impression that NOTAMs and such could be accessed there. I would assume other personnel also have their own displays. Is ERIDS just like a back-up source of information?


texts: Can a Pilot hold multiple foreign licenses and practice the privileges of it in each country?

texts:
Is it possible for a CASA CPL holder to convert to both an FAA and CAAUK license and hold all three at the same time?

Would the pilot then be qualified to exercise the privileges of the CPL in Australia (with a CASA registered aircraft), USA (With an FAA registered aircraft), and the UK (With a CAAUK registered aircraft)?


texts: What would be the challenges to taking off and landing a typical passenger jet at FL300?

texts:
Suppose it was somehow possible build a runway at FL300. Yes, doing so would be incredibly expensive, and it would be a mammoth civil engineering task, and the downsides would probably by far outweigh its advantages in practice; but for the time being, let's say that the desire to do it exists, and the issue of money has been resolved (as if by magic).

Let's also ignore the issue of getting the passengers, cargo, etc., to and from the actual aircraft, and focus on the aircraft operation itself.

Having constructed this runway-in-the-sky, what difficulties, compared to a similar runway built at ground level, would pilots and airplanes face when using it to "land" (if we can even use that term here) and take off, respectively, with a typical passenger jet (turbofan) aircraft?

It has been suggested that this is a duplicate of Would building an airport at 30,000 ft save money? (which also, in the question body, allows for one at 10,000 ft). I believe that this question is not a duplicate of that one because that question focuses on the cost of building such an airport and the savings in fuel expenditures because airplanes would already be near cruising altitude, while this question focuses on the challenges of landing at and taking off from an extremely-high-altitude airport while specifically ignoring the economic aspects.


texts: Why would METARs and ATIS both report exactly the same wind direction?

texts: I understand that METARs report wind direction as true and ATIS reports it as magnetic. But at Camarillo (KCMA) both are reporting the same wind direction and speed even though the magnetic variation is 12.5 degrees. Why does the written versus spoken rule not apply here?


texts: How frequently are airplane windows cleaned?

texts: When you’re driving on the highway, after sometime unwanted insects and dirt accumulate on your windshield. When you stop over at a gas station, you might clean it off. It’s likely the case for aircraft as well, especially during takeoff and landing. But how frequently are airplane windshields cleaned? And how are they cleaned? Does this include cleaning of passenger windows?


texts: What is the aerodynamic centre and how does it relate to the pitching moment?

texts: Okay so I have been trying to get my head around the Aerodynamic centre and the Pitching moment. Wikipedia really isn't helping much but from what I can gather the Pitching moment is a force caused by the lift from the aerofoil acting upwards from the Aerodynamic Centre (lift) and which acts around the centre of gravity (hence the tail must be configured to counteract this. Can someone please help me out here?


texts: How can I calculate the Obstacle Free Zone of an aerodrome?


texts: Is there a complete source for aircraft registration information?

texts:
I am building an app that requires access to commercial aircraft registrations, in the UK to begin with and then more global as I start to expand the service.

I have found this CAA site which works for now, but I would like to include all registered aircraft.


texts:
The Q400 has a cruise speed of 360kts, and on flightradar24 most Q400s that I looked at reached similar speeds during cruise. The ATR 72 has similar specifications yet only flies at 280kts. I'm currently designing a regional turboprop as part of a university assignment and I can't find a drag polar that gives 360kts as anywhere near the optimum speed for L/D ratio, 244kts was the cruise speed for my initial configuration. Is the Q400 likely flying at a much higher, less efficient speed? Why would this be done? Or has better technology allowed it to fly efficiently at this speed?
Edit: According to a pilot on this flight sim forum they used to cruise at around 200kts. This video shows Flybe (budget airliner) cruising at 240kts, FL240. Maybe the flights I've seen on flight radar are operating under different parameters at the moment, with fewer passengers and lower oil prices maybe 360kts is the best speed.


texts: Lindbergh's panel-- Ryan NYP-- what is this instrument and how was it useful?

texts:
Lindbergh's panel-- Ryan NYP-- what is this instrument and how was it used?

See this link-- it should allow you to zoom in by mousing around

https://www.amazon.com/Instrument-Successfully-Atlantic-Charles-Lindbergh/dp/B077RBRZTT

Consider the "T" shaped instrument at the lower center--

The top (horizontal) part is a bubble level -- it acts exactly like a slip-skid ball except the bubble deflects in the opposite direction as a ball would--

The lower (vertical) part is some sort of pitch level.  It is calibrated to show pitch attitude.  The glass tube may possibly have a part that we can't see, that disappears into the panel.

So why how was the vertical glass tube intended to be used?  Was it intended to provide useful information in cloud?  If so, would it actually have provided any useful information, or not?  Or was it just intended to display a precise measure of the aircraft's pitch attitude and thus angle-of-attack, during unaccelerated straight-and-level cruising flight in visual conditions, for the purpose of optimizing the airspeed and angle-of-attack for long-range cruising flight?

The calibration suggests that the instrument was intended more to detect large deviations than for fine-tuning the angle-of-attack in cruising flight in visual conditions, but it is hard to see how this would be of much practical use during actual cloud flying.  It's pretty much analogous to a simple pendulum, but with more damping.


texts: On an IFR flight, should I avoid class B and include approach fixes/procedures in the route?

texts: When creating an IFR route, should one route around and avoid class B airspace?  Should one include the IAF (Initial Approach Fix) of the desired IAP (Instrument approach Procedure) in your route?  Should one include the desired STAR and/or SID in the comment section or route section?


texts:
For analysing the FDR, data is downloaded to the local computer from the FDR and feed into the Analysing Software. I would like to know what is the file extension of the data stored on the FDR.
I came to the conclusion that it must be csv for storing all the data about Height, longitude, latitude and so on. Then this .csv file is feed into the Analysing Software for analysing. But I am not sure if I am correct.


texts: Covid-19 - Why are there still a lot of international flights?

texts: I hope this question is relevent to Aviation. If not, please let me know. Below is a snapshot from Flightradar24. While there are far less flights than usual, there are still a lot of flights en-route.  I thought there were controls put in place last week in several countries. Do these flights have special permission?


texts: What are the advantages of twin-fuselage aircraft?

texts:
During WWII, there were a number of twin-fuselage aircraft (notably bombers but some fighters). They were made by apparently combining two existing single-fuselage aircraft bodies together:

Twin-fuselages seemed to disappear after the 1960s but  recently, Virgin Galactic has come out with a twin-fuselage aircraft, the WhiteKnightTwo.

I understand the Virgin design as the space module (SpaceShipTwo) is designed to fit between the two fuselages. But aside from that special case, are there any advantages to twin-fuselage aircraft?

Was their design and introduction in the 1930s-1950s merely a strange historical accident (and if so, what was the reason d'etre then) or do they currently or potentially have advantages over single-fuselages such that we might see their return?


texts: What phraseology does ATC use with jet fighter pilots?

texts: What do they usually say or ask when the fighter pilot wants to take off, when it's in the air, and what is the reply from the fighter pilot?


texts: Are piezoelectric energy harvesters too expensive to be used commercially as a power source in drones or small aircraft?

texts:
Piezoelectric energy harvesters can draw energy from the mechanical loads and the vibrations in the fuselage/wings/blades of aircraft.

What are the disadvantages of such a system being used as an auxiliary power source if not the main one? Is it not worth the money?


texts: What are some good resources on Jet Design?

texts: I'm a student in high school, so please imagine you're talking to a toddler first, and second where would you advise I look for good documentation and guidance in jet engine design and tools to familiarize with.


texts: What is the official FAA definition of the term enroute?

texts:
I recently saw a ferry permit which included the following limitation:

  Flight in IMC authorized for ENROUTE operations ONLY

Great, IMC is allowed enroute!  But wait, where does the "enroute" portion of the flight start and end?

I did some research and found the following ICAO definition for enroute:

  Instrument Flight Rules (IFR): From completion of Initial Climb
  through cruise altitude and completion of controlled descent to the
  Initial Approach Fix (IAF).

  Visual Flight Rules (VFR): From completion of Initial Climb through
  cruise and controlled descent to the VFR pattern altitude or 1,000
  feet above runway elevation, whichever comes first.

That seems pretty straightforward, but I was looking for something FAA specific and found this in Chapter two of the FAA's Instrument Procedures Handbook:

  The en route phase of flight is defined as that segment of flight from
  the termination point of a departure procedure to the origination
  point of an arrival procedure.

That doesn't match the ICAO definition, but it also isn't from an actual regulation or LOI either.

This leaves arrivals and departures as slightly ambiguous, and they often start high in the flight levels where it can be hard to avoid IMC, even on a nice VFR day at the airport (and also seems contrary to what they are trying to accomplish).  Are arrivals and departures considered enroute or some other phase of flight?


texts:
Next week I am flying to an airport and going to have dinner. But I've never stepped out of my aircraft except at my home airport!

When I park on their ramp, do I keep the parking brake on?


texts: Why does TAWS alert depends on airspeed?

texts:
According to the TSO 151c:

  Speed. Airspeed or groundspeed must be included in the logic that determines basic
  GPWS alerting time for “excessive closure rate to terrain” and “flight into terrain when not in
  landing configuration” to allow maximum time for the flight crew to react and take corrective
  action.

As I understand for "flight into terrain when not in landing configuration" modes, in the guides corner speeds are given as from 190 KTS to 250 KTS. I can understand the calculations dependency on airspeed but do you have any idea how these speeds are selected? Are they regulated by FAA or EASA? As far as i know,

  §91.117   Aircraft speed.
  (a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).

but why 190 KTS? Is there any speed limits that should be obeyed for approaches and landing?


texts: What is this airplane with small wings at different angles seen at Paphos Airport?

texts: I landed in Paphos Airport in Cyprus and spotted this thing sitting in the sun near the runway. It has small 'wings' sticking out at different angles. What kind of plane is this? (Sorry for the bad photo.)


texts: Is it legal to fly GA aircraft in temperatures above what is shown on the performance charts?

texts: Most Cessna aircraft have performance charts the range from 0 to 40 Celsius. I've had a CFI tell me that the FARs prohibit flight if the OAT exceeds 40C or whatever is shown on the performance charts. Is that a true statement? I have not found anything in Part 91 that addresses this.


texts: What happens when a "ground effect" plane approaches the sound barrier?

texts: Does the shock wave inhibit or contribute to lift? What is the ideal speed to fly near or on the speed of sound while using the ground effect?


texts: Why does the 0 radial on a sectional's VOR appear not to point to magnetic north?

texts:
I have been scanning sectional charts and have noticed that the local magnetic declination is always a few degrees off from the 0 radial of VOR's around it. I have been told that the two are supposed to be the same. See image below from skyvector as an example. In this image, the local magnetic declination is 14.5 degree east. The OED VOR however has its 0 radial pointing roughly 19 degrees east of true north (which can be seen from the adjoining longitude line).

This is one example, but I see similar discrepancies all over the U.S. I have read in many places that VOR's 0 radials point to magnetic north but I have not seen many actual cases on sectionals. What gives? Possible reasons:

They do point to magnetic north. But something about the sectional is causing the apparent discrepancy
They don't point to magnetic north but they did at some point. Since magnetic declination changes over time, the VOR's 0 radial was truly pointing at magnetic north in the past but is no longer.
They don't point to magnetic north for another reason.

If VOR's aren't truly aligned to magnetic north, then it seems that going outbound on radial 090 from a VOR will not necessarily mean you are going magnetic east. And I have read on online articles and other sources that it is useful to use VOR compass roses when plotting magnetic courses. This would appear to cause errors of 5 degrees or so which seems significant.


texts: Where can I find airport taxi instruction "code names"?

texts:
At larger airports, common taxi instructions are sometimes "named" for brevity as they are repeated often. For (an entirely contrived) example,

  Taxi to terminal via alpha, tango, foxtrot, mike four, sierra

could be shortened to something like

  Taxi via red-flower

Where can these common taxi route definitions be found?


texts: What is the reason for the fence aft of the static ports on some airplanes and helicopters?

texts: Airbus AS350 helicopters and Bell 206 helicopters have a 1/2" long fence behind the static port. CRJ 200/700 have a .060" step on the aft side of the static port. What would be the reason for these?


texts: Why do the MiG-15 and MiG-17 have a split air intake in their noses?

texts:
MiG-15 and MiG-17 both have a split air intake in their nose. However, they have only one jet engine.

So why is the air intake split? Wouldn't it be a lot less drag to just let the intake flow cleanly into the engine?


texts: How can I calculate the moment coefficient around the center of gravity?

texts:
Hi guys I was wondering if you could help me with the following problem:

Wing surface area= 260m2 (sw)
MAC= 6.608m (cw)
horizontal stabilizer surface area=69.5m2 (st)
distance from the cog till the aerodynamic center of the horizontal
stabilizer=30m (lt)
change in downwash angle vs angle of attack de/da=0.5
distance from wing til aerodynamic center (hacw) = 26% of mac angle (hacw)
of the wing is 0.12 per degree (aw)
angle of the stabilizer = 0.07 per degree (at)
downwash stabilizer at an angle of attack of 0 is e0=0
moment coefficient of the wing in the aerodynamic center is
Cmacw=-0.04
CoG=31%

Calculate the moment coefficient around the CoG(Cmcg) of the entire airplane when the angle of attack is 3 degrees and the angle of the stabilizer is 1.5 degrees aircraft nose up.

I know the answer which should be Cmcg=-0.022 but I have no idea how it is calculated.

I am sorry, what i did was the following: I calculated the tail volume coficiency which is 1.213564, the position of the neutral point being it 0.61396. I am trying to use the following formula:

$C_{mcg}=C_{macw} + a_w  a_w (h-h_{acw}-{a_t\over a_w} V_h (1-{\Delta e\over\Delta a})) + a_t V_h (i_t+e_0)$

when filling in I do the following

$-0.04+a_w A_w (0.31-0.26-{a_t\over a_w} 1.213564 (1-0.5) + a_t × 1.213564(i_t+e_0)$

for aw and at I am not sure to use the 0.12 and 0.07 or do it times 3 and 1.5 for the degrees. it seems to be angle of the stabilizer but I am not sure. e0 I think is 0 but again not sure.


texts:
Up to which height is the ground effect still significant enough to be taken into account? Would this height be sufficient to actually fly above the ground, overcoming at least trivial obstacles like trees?

The early transatlantic flights were done with heavy loaded planes that had difficulties taking off (only at the end of the runway, and only just). Could it be that these planes were flying within ground effect for rather extended distances, before picking enough speed to complete the take off?


texts: Is the air in a jet engine supercritical?

texts:
Nitrogen has a critical point of 126.2 K and 3.4 MPa (34 bar). Air contains 75 % of nitrogen

  For example, nitrogen has a critical point of 126.2 K (−147 °C) and 3.4 MPa (34 bar).

source : https://en.wikipedia.org/wiki/Supercritical_fluid

In a jet engine pressures often exceed 34 bar ( as seen on Wikipedia, where for example the GE9X is shown to reach 60 times ambient pressure ), the critical temperature of nitrogen is exceeded at room temperature. So is air ( fluid ) in the high pressure regions of a jet engine supercritical ?


texts: Can Flex thrust be lower than climb thrust?

texts:
Let's restrict this question to airliners with 2 jet engines.

For the remaining of the question, I'll use the term flex to designate reduced take off thrust as I'm more familiar with airbus's systems. Flex will be the thrust selected when thrust levers are in the flex detent and climb thrust the one selected when lever are on the "climb" detent without autothrottle engaged. I assume other manufacturers have an equivalent way to easily select those values.

Both flex and climb thrust are lower than TOGA thrust. In good condition (long runway, good weather, almost empty aircraft,...), how low can flex thrust be? Can it be lower than climb thrust?

In this case, what is the rational for accelerating from flex to climb thrust given flex is made to increase engine lifespan by reducing thrust?


texts: Why do pilots cut the reverse thrust below 40 km/h?

texts:
In a Microsoft Flight Simulator 2004 Boeing 747 landing tutorial, it was said to cut the reverse thrust after decelerating to 40 km/h.

What happens if that was ignored all the way to a complete stop? Would the plane start moving backwards?


texts: How many fuel pumps does a Katana DA20 have?

texts: How many fuel pumps does a Diamond DA20 have? And since the fuel pump sends fuel to the engine, if you turn it off after the takeoff as the check list says, how will the fuel reach the engine?


texts:
I'm estimating some wing parameters for an imaginary airplane (simple college project). We are allowed to use coefficients for any basic types of flaps (plain/split/slotted/Fowler etc), but since I'm doing a glider I'd like to go with the one that's really used.

tl;dr - What kind of flaps are used in modern gliders (preferably training ones)?


texts: What are these aircraft at AMARG? Why are they dismantled this way?

texts:
At the AMARG boneyard (Tucson desert, Arizona), there are tons of aircraft, but a limited number of models are dismantled according a special way: wings or tail or both separated from the fuselage:

Image from Google Maps

Source, reframed

I doubt all tails will suddenly be used as spare parts...

What are those military aircraft? why are they systematically dismantled this way?

(Not sure the question is on topic.)


texts: Why aren't there aircraft with forward-mounted vertical stabilizers?

texts:
Many aircraft have the horizontal stabilizers mounted in front of the main wings (this is called a canard configuration); however, to the best of my knowledge, there don't seem to be any aircraft with vertical stabilizers in front of the wings.

Why is this?


texts:
Does the thrust of the fan in a turbofan jet engine decrease proportionally with decrease in the diameter of the fan?

As the fan in a jet engine is responsible for over 70% of the total thrust can a spark ignition engine driven fan of 1 meter give an equal thrust of a 1 meter diameter turbofan jet engine with the jet exhaust thrust removed form the sample? All inlet duct and shroud would be identical, also the fans.


texts: What was the Trim Problem on the Brabazon's First Flight?

texts:
In this video, starting at 18:15, the copilot on the Bristol Brabazon's first flight recounts that the aircraft became airborne a little sooner than its pilots expected, and that despite the captain holding the yoke fully forwards, the nose continued to rise. The copilot responded by retarding the throttles and then advancing them again, which cleared up the problem. He does not mention any adjustment to the trim, though he states it was fully forwards prior to his action. He also mentions that an adjustment was made to the elevator to fix the problem for subsequent flights.

I am curious as to what caused this problem, and in particular, why it did not recur when the copilot reapplied power. I realize that the copilot may have omitted some key details, such as the aircraft accelerating before the reapplication of power (this occurred at 200 - 300 feet, and the film of the take-off appears to end before it has reached that altitude.) I am also aware, from other reading, that the Brabazon was intended to have a complex (at least for the time) hydraulic control system that was intended to smooth its response to turbulence, that never really worked properly, but it would seem an unnecessary risk to have it engaged for the first flight.


texts: Will I have to do a checkout ride at a rental place if I'm already familiar with the aircraft type?

texts: I've done my training and checkride on Piper Archer (PA-28A). Will a rental place make me take an checkout ride with an instructor if I wanted to rent the same plane model?


texts: Can a student pilot start flight training before they get their student pilot certificate and medical?

texts: Let's say someone wants to start doing some flight training in the United States with the eventual goal of receiving a private pilot certificate. They have yet to get a medical certificate or student pilot certificate. Can they go ahead and start getting some flight training logging dual received?


texts: How can the Cirrus Vision jet be cheaper than its competition?

texts:
Cirrus Vision SF50 costs USD 2 million, compared to USD 5 million for comparable private jets.

How is Cirrus able to offer a jet at such a substantially lower price? What compromises are customers making when buying this plane versus a competing one (Eclipse Canada, Cessna Citation M2 and Embraer Phenom 100 as per https://www.usatoday.com/story/money/2017/07/06/price-cutting-private-jet-shakes-up-aircraft-market/102607220/).


texts: Zenith-Add horsepower, NASA-add drag: to create lift. How is this possible?

texts:
Available horsepower and adding drag to an airplane both create extra lift?  How is that possible?

Available Horsepower

According to the Zenith, available horsepower not used to overcome form drag and induced drag contributes to rate of climb.
Adding drag

NASA's report on the X57, states that drag might need to be added to get rid of excess thrust to create more lift.

From the conclusion of that NASA report on span-wise propellers generating lift:

  A potential constraint on the design of the high-lift propellers system is the total thrust. If large amounts of lift augmentation are required from the propellers, then high thrust values from the high-lift propellers are likely. If these propellers produce excess thrust, then the aircraft will be unable to sustain flight at the desired speed. This implies that drag producing devices may need to be added to the aircraft or the primary propellers operated as windmills to produce additional drag.

(High-Lift Propeller System Configuration Selection for NASA's SCEPTOR Distributed Electric Propulsion Flight Demonstrator, NASA)

This concept seems to be exactly opposite of the first concept!!
Rumours: Ultralights reach a max speed, any extra power is then converted to lift. Is this true?

How do these concepts work?


texts: What, as far as the FAA is concerned, is required for Ag Application?

texts:
There are lots of "you need this..." comments, but I'm wondering what is required, legally, by the FAA?
A Commercial Rating, of course.  Flying for money and all.
A Taildragger Endorsement because the plane will probably be a TD.
A High Perf Endorsement because the plane will have over 300hp and very likely electric flaps - but maybe not cowl flaps.
But the FAA doesn't care about Insurance, does it?
And really it doesn't care about the chemicals either, does it?  I mean in their statutes.
The Chems have state and fed guidelines, of course, but beyond the purview of the FAA.
Are there other ratings or certifications involved under the FAA?


texts: Could you please give me the steps or procedure to start the a/c twin otter gas turbine engine?


texts: Are aviation regulators generally slower to issue orders affecting their "own" aircraft manufacturers?

texts:
It did not fail to escape the attention of commentators that the US Federal Aviation Authority was amongst the last aviation regulators to issue an order grounding the 737 MAX.

Is there evidence to show that this is a pattern - that US, European, Russian (or other) regulators tend to be slower to issue orders or directives that concern aircraft made by manufacturers within their own country or bloc?

What would count as an answer

"Evidence" in this case would be based on figures showing time to respond by different agencies in multiple cases (enough to indicate a pattern).

What does not count as an answer

I am not asking for opinions on whether the FAA or EASA or other agencies are politically sensitive (I am sure they are).

Though I am willing to bet that it will turn out to be the case that agencies tend to be slower to act when it would affect interests that are closer to home, I don't need to read speculation about why; I don't think it will be any more illuminating than the interminable exchanges about how Airbuses are better than Boeings or vice-versa.

Similarly, although questions have been raised and concerns expressed about the FAA's inspection regime and the degree to which it allowed Boeing to self-certify aircraft, that (and the regimes and processes of other regulators) is not the question here.

I should have guessed that this would quickly descend into ra-ra declarations about superior American pilots and ways, backward and corrupt non-western political systems, and so on. I wouldn't want to deny anyone their fun, but it's exactly what is not an answer to the question.


texts: Can 737NG GPWS and other warning voice lines/sounds be played in headphones instead of cockpit speaker?

texts: I watched a couple of cockpit videos on the 737NG landing, and I noticed GPWS in some of the videos does not announce 500ft, 400ft, 300ft, etc. Does this mean the pilots have routed these sounds into the headphones, or they have been disabled on the particular operator’s aircraft?


texts: Would titanium be a better option for aircraft skin if cost were not a factor?

texts: If price was not an issue, would titanium be a better option to use as the skin of airliners as opposed to aluminum?


texts: Why are flight recorders generally located in the tail?

texts: Is there a particular reason why FDRs and CVRs and associated similar bits of equipment are kept in the tail section of a plane?


texts: Why do commercial helo pilots wear helmets?

texts:
I've been on my fair share of commercial helo rides, primarily in Canada.  Over the course of more than ten rides in three different kind of helos (Bell 407, 412, and I think one other) there was only one time when the pilot wasn't wearing a helmet.

It's worth noting that these flights were taking off and landing in very remote areas of the Selkirk mountains, usually on glaciers.

At the same time, I have been around (US) flight schools since I was 15 years old, and I've never seen an instructor or student helo pilot (flying R22s and similar) wear a helmet.  Also, fixed wing pilots don't wear helmets.

Why do commercial helicopter pilots wear helmets, when instructors and students don't?

It's a little hard to see, but here's a photo of one of the choppers, and you can see that the pilot is wearing a helmet.


texts: Is a chambered fan more efficient than a ducted fan?

texts:
A chambered fan is not exposed to the oncoming airflow in forward flight.
I am working on a VTOL design that uses a chambered fan.

There will be a wing attached to top of the thrust arms.

Could it produce 12,000 pounds of lift force using a GE T901 with 3,000shp with 8' dia. contra rotating fan?


texts: What's on the upper deck in the picture (circled) of Cathay Pacific Cargo Boeing 747-8F?

texts:
Cathay Pacific Cargo Boeing 747-8F

Image Source

Is that a resting area for pilots or passengers seats?


texts: Which aircraft had such a luxurious-looking navigator's station?

texts:
I'm reading the BBC's How Fiji changed the way we travel; The little Pacific island nation was the first to incorporate GPS into its aviation system – and in doing so forever changed the way we get from Point A to distant Point B. and saw this photo of a spacious navigator's station with a large, elegantly designed desk, bay windows, and a small set of instruments.

What aircraft and timeframe was this? Does the photo portray a commercial flight?

bonus points: Were flare guns routinely stored out in the open like that at the time?

  Until the late 20th Century, flight crews often included a flight navigator whose job it was to keep the plane on course (Credit: Museum of Flight Foundation/Getty Images)


texts: Why does the faster-moving air over the static port not result in a lower static pressure?

texts:
I understand the concept that the static port is measuring "static" pressure, meaning the pressure the air is exerting on its surroundings.  However, there is also Bernoulli's principle, which, put simply, states that as the velocity of air increases, the pressure it exerts on its surroundings decreases.  We see this in effect in venturis, of course, but it seems to me that Bernoulli's principle would also imply that the pressure observed from the static port would similarly decrease as the aircraft accelerates.  Obviously this doesn't happen however, since the altimeter is unaffected by acceleration.

Thus my question: why does the faster-moving air over the static port not lower the pressure it exerts?

Here is a video explanation of Bernoulli's principle being used in pitot-static systems, which seems to suggest the static port would indeed observe a pressure decrease (I've labeled the part I think the narrator is using as the static port):


texts: Does one-engine cruise consume less fuel than two-engine cruise?

texts:
Scenario 1. A two-engine airliner experiences rapid depressurization and makes an emergency descent to 10,000 ft, and diverts to the nearest airport.

Scenario 2. The same two-engine airliner experiences rapid depressurization after it has lost one of its two engines and makes an emergency descent to 10,000 ft, and diverts to the same nearest airport.

In which scenario between the two does the airliner consume a greater amount of fuel, and why?


texts: Is thermal expansion/contraction a major design problem for large subsonic airplanes?

texts:
Most large airplanes flying today are mostly metal, which has a relatively big coefficient of thermal expansion. Cruising altitudes of commercial jets can reach 10 km or more, where the air gets down to about -50 Celsius. Room temperature is more like +25 Celsius, and I would not be surprised if that large fuselage, sitting under the sun, gets up near +50 C.

This is quite a range of temperatures to handle. It would cause some contraction/expansion of metals. The larger the piece of metal, such as a wing spar or long airframe beam, the greater the contraction/expansion.

Is this a major design problem for large aircraft, and how is it handled?

EDIT: only interested in subsonic designs. I'm concerned about the cold high altitude air cooling most of the fuselage and making it contract. The nose and leading wing edges might not suffer from this, but I expect the rest of the aircraft will.


texts: Where does the Olive Branch (KOLV) class D ceiling meet the Memphis (KMEM) class B floor?

texts:
I'm having an internal debate on interpreting the Class D ceiling in part of the the Memphis TAC. My understanding was in the case of a Class D under a Class B shelf, the ceiling of the Class D ends at the floor of the Bravo, or in this case: 1,800ft MSL.

However, the [29] box printed inside the area of the Class B/D is causing  confusion. Is this explicitly stating the Class D does extend to 2,900ft MSL or does it end at 1,800ft MSL as I originally thought?


texts: Are there any IFR-certificated and equipped aerobatic aircraft?

texts: Are there any acrobatic-category aircraft that are also type-certificated/rated and equipped for flight under the instrument flight rules?  What limitations would be placed on such an airplane when flying as an IFR aircraft vs. a VFR aircraft?


texts: Does the F-4 Phantom use (have) differential horizontal tail deflection?

texts: Is differential horizontal tail deflection used to roll the aircraft around the longitudinal axis along with the ailerons / spoilers and a bit of rudder?


texts: What is an Inertial Navigation System? How does it work?

texts:
In this question, the answer notes that some ADS-B systems are connected to Inertial Navigation Systems (INS), and says they are less accurate than GPS.  What exactly is an INS?

A couple sub questions:

Why is it less accurate?
The other post mentions they tend to
develop biases as they get older, why is that?
Are they being phased
out?  Or are they used as backup?


texts: Which civil airport has the longest runways in total?

texts: It's quite easy to google information about which civil airport has the longest runways, but what I'm really looking for (and having a hard time to find) is which airport has the longest runways in total - I mean if you add up all the lengths, disregarding the direction - which one be the winner?


texts: How did Northrop Grumman propose to make the Global Hawk nuclear powered?

texts:
Reading further after receiving this answer, I saw the section on nuclear power in the Wikipedia article on the Northrop Grumman RQ-4 Global Hawk:

Nuclear power
Sandia National Laboratories and Northrop Grumman have studied the possibility of equipping the Global Hawk with a nuclear power plant with US Air Force Research Laboratory funding. A nuclear powered Global Hawk would have a very large range and endurance, and more power for on-board systems. Apart from the technical feasibility, the major drawback however is the fact that drones sometimes crash. So whether this type of propulsion will ever be used on Global Hawk (or any aircraft) is questionable.64, 65

Those references do not give may details on the plan.
Radioisotope thermoelectric generators or RTGs can certainly be compact enough, and generate hundreds of watts or more, but I don't know if they could produce enough power to drive an electric engine.
Was the idea to use electric propulsion, or to somehow generate thrust through direct heating of the air? Or something else?
Nuclear powered aircraft are usually envisioned as quite large, so the proposal to add nuclear power to a Global Hawk may have been substantially different.


texts: What is the exhaust from the end of jet wing prior to landing?

texts: What is the exhaust from the end of jet wing prior to landing ? My guess,excess fuel from powering down engines.


texts: What determines the direction of rotation for counter-rotating propellers?

texts: As Wikipedia and other sources make clear, most twins with counter-rotating props are configured with the left (#1) prop turning clockwise (as viewed from behind the plane) and the right (#2) prop turning counterclockwise. But there are significant exceptions, such as the P-38. What the sources do not make clear is the reason for the exceptions. There are a few vague comments about the P-38 having "unsatisfactory" handling as originally configured with the common setup, but nothing that helps me understand what aerodynamic or other issues might make a P-38 or any other plane a candidate for reversing the rotation directions. I realize that there are potential issues with coupling to tip vortices if the engines are near enough to the wingtips. And I assume that there might be effects related to air impinging on the fuselage, or FOD from stuff entrained in the airflow during ground ops, or maybe issues with where ice being slung from the prop blades impacts other structure. But I am wondering if there is a more general aerodynamic principle which drives the rotation direction decision.


texts:
Apologies for being so broad in the title but this will consist of a couple of questions in one.

As I'm sure most of use are aware modern commercial aircraft being manufactured no longer incorporate a flight engineer, this role - as far as I know - has been taken over by onboard systems monitored by the pilots.

Obviously there are a number of airlines out there flying older aircraft that do require a flight engineer, which airlines still actively hire F/E's? Do airlines still train people for this position or purely rely on hiring people already trained? I'm thinking more along the thought process here of 'When the older F/E's retire, how are they replaced?'

Finally, what happened to the F/E's when this job was phased out? Were they retrained as pilots? Merged into an office job? Flat out dropped from the company?


texts: Do landing strips suffer from landing wheel tire tracks?

texts:
I've now seen several landing strips up close and there are lots of tire tracks from planes' landing wheels. I wonder if it somehow modifies the properties of landing strips to make for poorer landing conditions.

Do landing strips suffer from lots of tire tracks?


texts: What were the U.S. Air Force's first 2-crew fighter planes?

texts: The Navy has had 2-crew planes since at least as early as 1944 with the Grumman F7F Tigercat but when did the U.S. Air Force adopt 2-seaters. Does the Navy prefer 2 crew and the Air Force prefers 1? Was the McDonnell F-101 Voodoo one of the first AF 2-crew?


texts: How to build a 2 mile long runway on a 1 mile square island?

texts:
On Puzzling.SE I found this question:

  You have a 1 mile long x 1 mile wide private island that you wish to
  turn into a resort. A plane requires a 2-miles long runway to take
  off. What do you do?

There are plenty of answers, among them some irrational ones, but also some good approaches to solving this puzzle.

From an aeronautical point of view, what would be a reasonable solution?

I am thinking about a vertically curved runway. To meet the 2 mile requirement it would need to have an angle of (estimated) 25° at the edges of the curved runway. It would go diagonally across the island and by its curvature add the extra length needed to the √ 2 length of the diagonal length.

I am sure there must be a better solution though (extensions of the island shouldn't count!)


texts: What type of aircraft is this Airplane in Riga (junkyard)?

texts:
My relationship with the Mil Mi-6 led me to this Wikimedia photo of a time-worn Mi-6 in Riga airport.

In the photo there are the Mi-6, a Skoda Fabia, some picnic equipment, other stuff and a supersonic jet fighter (is it really a jet fighter?) with a large, red "43" on the nose. Here it is a detail from the wikimedia photo

What airplane is the "43" red?

Bonus points for the white "27" on the left (but it's difficult because you have just a detail of the nose) and the jet bomber (?) on the right, partly hidden by the red metal ladder.


texts: What is the weight saving of windowless fuselage for cargo aircraft?

texts:
What is the weight saving of a windowless fuselage for cargo aircraft?
Does anyone have a rough estimation?


texts: What would need to change for supersonic airliners to be the norm?

texts:
I know that supersonic airliners have never been widespread, by reason of cost, engine technology, aerodynamics. Yet can these difficulties be overcome within the next 20 years?

I know of Concorde's retirement and ongoing attempts at Supersonic Business Jets.


texts: How does a flying wing keep from going into a flat spin when maneuvering?

texts:
How do flying wings, like the B-2 Stealth bomber, actually keep themselves from yawing out of control without a vertical stabilizer?

For the record, I assume this has to be a simple mechanics process.  Why?  Well flying wings go all the way back to the 30s.  One of the earliest (and my personal favorite) is the N-9M, which was a scale model of the XB-35, a prototype bomber for the allies during WWII.

They didn't have flight control computers back then, and the only control complaints I recall them having is that early versions had a tendency to flip over backwards when approaching stall speeds, well, that and the ground effects were pretty strong. But, no mentions of going into flat spins when going into hard maneuvers (that I recall).

So how do they control that Y axis on flying wings?  Are they perhaps more susceptible to a flat spin than a regular design (even if those risks can be kept to an acceptable minimum)?


texts: Can an air traffic controller refuse to give service to an aircraft based on moral grounds?

texts:
Today I learned about a Twitter account that tweets arrivals and departures to/from Geneva, of aircraft used by dictators.

I was wondering if an individual air traffic controller could refuse to give service to a given aircraft based on moral grounds, without legal consequences?

Maybe I'm a pacifist controller and I prefer to not handle a military aircraft sending troops somewhere. Or I don't like dictatorships and I don't want them in the country/airport where I operate.

Is there any legislation that could protect such objectors? To narrow a little the question, let's stick with Geneva in particular, or Europe in general.


texts: I would like to know if, in addition to any MEL requirements, there is any regulation or requirement about having an operational TCAS II while operating in US airspace?


texts: Why does V165 have two different MEAs over the same route section?

texts: Why does V165 have two distinct MEAs which vary by a large factor (apart from the 180$^{\circ}$ rule of altitudes) considering they would be clearing the same obstacles and receiving signals from the same NAV aids?


texts: How does induction ice form in and affect jet engines?

texts:
Recently someone talked to me about the possibility of induction ice on the engine:

He told me that because of conditions around fan and compressor blades (mainly because of pressure and temperature) some ice may form, under certain exterior conditions, and destruct the engine by ingestion or by stall of boundary layer.

My question: It is really possible? If yes, can someone explain to me how it works?

I don't find proper explanation on Google.

I raised this question after this hypothesis:

  Icing inside jet engines can become a hazard at high altitude near large thunderstorms, when moisture turns into tiny ice crystals that can be sucked inside an engine. If the ice melts but then freezes again on metal surfaces, accumulating ice can either break into chunks that damage turbine blades, or melt and douse the ignition system.

source


texts: Are turbofans compensated for gyro effect?

texts: In a multi-spool design is the gyro effect canceled or mitigated by having the two or more spools spinning in different directions?


texts: Can large airliners such as a 747 maneuver without electricity?

texts: Small aircraft have the flight controls physically linked to control surfaces by some kind of cable and pulley system. For a large aircraft such as a 747, are the control systems mechanically aided and if so, can they be used without power?


texts: What factors/equation(s) are used to relate aircraft weights and cruise speeds?

texts:
With the recent coronavirus issues, there have been lots of empty seats flying around, especially on long haul flights.  I checked the seat map for a recent SFO-SYD flight (777-300) and there were 224 empty seats out of 340 available.  This obviously means the aircraft was much lighter than usual for this run - a quick estimate gives me 25 tonnes less weight just in people/baggage.  To get to the actual question, when doing flight planning what equations or other mathematical factors go into computing how this impacts the climb rate and cruise speed for the flight?  I'm familiar with the concepts of induced drag but I don't have an intuitive or empirical understanding of the actual impacts the reduction in weight would have.

Does taking 25 tonnes of weight from the airplane move the climb rate by 100 ft/min, or 1000 ft/min?

If we have 25 tonnes less "cargo", this means we also need less fuel to lift and carry the aircraft... but how much less?  How do we compute the fuel savings for the lower take off weights?  I know there have to be formulas (or at the very least charts/curves) but I didn't have much luck finding them.

Is the cruise speed meaningfully increased by the lighter weight?  Or does it just require less thrust (i.e. lower fuel burn) to fly at the same cruise speed?

I realize these are framed as discrete questions, but I think they're all inter-related in a way that's close enough to put them into a single post here.  Moderators feel free to disagree  ;-)


texts: Relationship of propeller RPM, blade pitch, and drag at very low blade pitch angles

texts:
I'm researching the 2016 crash of a PIA ATR-42 in Pakistan, the report on which was recently released. Link to the report: https://www.caapakistan.com.pk/Upload/SIBReports/AAIB-386.pdf
During the incident, a series of malfunctions caused the propeller on a failed P&W 127M engine to not feather although it was commanded to do so. The overspeed governor was also not working; as a result, blade pitch began to decrease and RPM increased past the normal overspeed stop (>120%) causing massive drag.
However, at a certain point, the RPM suddenly dropped (<25%), causing a massive decrease in drag. This was critical to the sequence of events as the pilots were standing on the rudder to compensate for the drag, the sudden disappearance of which caused them to overcontrol and lose control of the aircraft within a couple of seconds.
What I don't get is why the trend toward increasing propeller RPM as blade pitch decreases would suddenly reverse if the pitch gets low enough. This is what the report says:

"If  blade  angle  decreases below  a  certain  angle (depending  on  the  Np  and  the  power  absorbed  by  the  engine),  the propeller  in  wind-milling  does  no  longer  generate  power  but  needs power  to  stay  at  the  same  rotational  speed.  With  a  failed  engine,  the decrease  of the blade pitch  angle below  a  certain  threshold  leads  the propeller speed to decrease."

"There was sudden drop in Np-1. It  was  because  of  the  reason  that  the  blade pitch  angle (most  likely) decreased  further  up  to  a point  where  the  power  generated  by  propeller  was lower than power absorbed by the engine and it may have later  moved  to  a  stable  physical  position.  Np-1 decreased below 25% and then stabilized lower than 5%, with blade pitch angle close to low pitch in flight. This  sudden  decrease  in  the  Np-1  resulted  in sudden depletion of large amount of drag."

What do they mean by "the propeller  in  wind-milling  does  no  longer  generate  power  but  needs power  to  stay  at  the  same  rotational  speed"? If it needs power to stay at the same rotational speed, where was that power coming from when it was spinning at 120% np for several minutes with the engine shut off? And if RPM remains high, why would a further decrease in blade pitch cause less "power" to be "absorbed" by the engine? What exactly do they mean by "power" in the first place?
Furthermore, if this drop in blade pitch towards "low pitch in flight" resulted in a decrease in RPM and a commensurate decrease in drag, the next part of the sequence of events also needs clarification. After recovering from the snap roll and dive, the crew were faced with a situation where the propeller on the failed engine was rotating very slowly (under 5% np) with blade pitch at or slightly below zero degrees, but was also causing even more drag than when it was at 120%. How is this possible, if just moments earlier, blade pitch decreasing toward that value caused drag to decrease?
Any help would be appreciated. Thanks.


texts: What terminologies are used when ATC instructs a pilot to stop or proceed with his transmission?

texts:
If some pilot forgets to release his mic button, distracting everyone on the frequency, what terminology can be used by an ATC to stop it?

And if another pilot stop transmitting his message until the former pilot release his mic button, what terminology can be used by an ATC to make him resume and finish his transmission?


texts: Why does the BAe 146 have higher maintenance costs than other comparable jet aircraft?

texts:
In many discussion(1)(2) it is stated that the BAe 146 has higher maintenance cost and higher cost of operations in compare to other jets due to its complexity.

  Quoting IslandHopperCO (Reply 21): The PSA (then USAir) BAe-146s were
  parked in the desert in 1991 due to high maintenance costs according
  to USAir. More likely was that USAir couldn't turn a profit on the
  western routes that PSA used to make money on, because those routes
  were dropped when the plane were parked.

  No that is pretty much correct...PSA also had major problems with
  reliability. In fact BAE provided them with a spare because they broke
  down so much. Who knows if they would have gotten rid of them because
  of that. They were kinda ugly but in a cute way....that smile really
  did it!

Why are the maintenance and operating cost higher?
Why is it more complex than other jets?


texts: What causes aircraft to swerve during takeoff?

texts:
I notice on some commercial flights that the aircraft can begin to swerve left-to-right during takeoff before we leave the ground. Sometimes this can become very exaggerated, very hard left-to-right swerving. This is typically from around mid-way through the takeoff run, becoming most severe immediately before takeoff.

My first thought was perhaps it is an inconsistency in the runway from the airport I frequent but have noticed it once or twice at other airports as well, and across different carriers. However, it feels more like when driving a car and you swerve, then overcompensate the other direction and it becomes a vicious cycle.

Other factors may include wind - but I've been in high-wind takeoffs before and it didn't have the same jerking motion.

Any explanation to this, or am I just paranoid?

*Apologies for lack of knowledge re: terminology


texts: Does an rc plane tail also have airfoil or is it just flat material?

texts:
I've chosen an airfoil for the wing, now i'm confused weather i should do the same for tail or just attach a flat piece of wood as tail. I'm going for conventional tail design.
This is my first ever plane so sorry for the dumb question.


texts: What are cloud clearance requirements around scuds?

texts:
I'm a private pilot (in the U.S.) and I was doing hood instrument training with my instructor under VFR.  I put on the hood and we did an instrument takeoff, and I flew up to 4,500 feet to do some VOR holding pattern practice, all while under the hood.  We were in a Class C airspace.  At 4,500 feet I peeked out from under the hood, and to my astonishment we were surrounded by thin wispy clouds.  I think we even flew through one and couldn't see outside the airplane.  It looked to me that we were obviously in violation of VFR cloud clearance requirements because the clouds were less than 100 feet from the plane and we flew through some of them.  I said this to my instructor, and he insisted that we were still VFR and that I should get back under the hood and
continue the holding procedure.  I insisted again that we were clearly in violation of VFR cloud clearance requirements, and he again insisted that we were fine and we should keep flying.  After three or four times he finally conceded, and we descended and did some practice instrument approaches while clear of clouds.
On the ground after the flight, my instructor said that the clouds were "scuds" or clouds just beginning to form, and that they were see-through.  I'm a little shaken by this because I've worked with this instructor for a year and a half and I haven't seen any reason not to trust him, but I feel a little betrayed by this.  My instructor is probably in his 60s and has been flying and instructing for many years.  If I'm wrong and we were legal to fly through the scuds VFR then I'll admit that, but it seems to go against my education.  Maybe pilots normally fly through scuds with no problem, and if that's common practice for pilots then I guess I'll do that.  But if he let us fly into clouds illegally and then insisted that we keep flying, I'm a little shaken by that because I've worked with him for a long time and he seems to be a good instructor.  I'd like some clarification on this.


texts:
For a planned ferry flight under FAA Part 91, this is the scenario:

Two of us, let's call us A and B (rated pilots for that airplane), want to sit in front and do the flying.
A highly experienced pilot, C, will accompany and supervise the flight, sitting in the back seat.

Insurance insists that C be acting PIC throughout the flight.
At the same time, insurance has explicitly said that C can sit in the back while doing so.

This doesn't accord with C's own understanding of what is legal in an airplane that only requires one crew member. My own reading of who can be PIC doesn't say anything about where in the plane they have to sit.
So the question is: Can someone act as PIC while sitting in the back seat in a single-pilot airplane?
Relatedly, if the answer to the above is Yes:

Suppose B is a CFI
A manipulates the controls.
Can all 3 pilots log PIC time?

A is sole manipulator of the controls;
B provides instruction;
C is acting PIC?


texts: Does Part 135 duty time begin at the start of a part 91 owner flight which occurred immediately before?

texts:
You are asked to fly a 91 owner trip to a destination. A 135 trip comes up after your owner flight.

Does your 135 duty time start when company asked you to fly the 91 owner flight?


texts: Is it possible as a pilot to get the ICAO proficiency language level for a not official language in the ICAO?

texts:
I was wondering if it is possible to get the proficiency language level in German for example, as it is not an official language for ICAO. If I would want to apply for a German airline as a pilot, can I get that document, the same as I can get it for Spanish or English?
I am not 100% sure but I think pilots in Germany, Austria and Switzerland can communicate in German so I guess they need those competencies (although when being native you don't have to take the exam)

Maybe it's a dumb question but I haven't found an answer yet.


texts: How does a flex takeoff increase fuel consumption compared to a TOGA takeoff?

texts: I read this also in the FCTM green operating procedures that doing a flex takeoff increases fuel consumption as we have a longer takeoff phase


texts: Why does the Boeing 737 sit so low on its wheels compared to the Airbus A320?


texts: Was the 727 the last airliner whose doors could be opened in flight?

texts:
The Boeing 727, put into service in 1963, had the distinction of a rear doorway with stairs that could be lowered so that passengers could embark and disembark at rural airports which did not have their own airstairs.  As initially designed, this door could be opened even whilst in flight as it is not the usual "plug" style.

In 1971, the hijacker known as DB Cooper famously used the rear door to make his parachute escape mid-flight. According to wikipedia, the CIA also used this feature to drop passengers and supplies mid-flight.

In the wake of the DB Cooper incident and other hijackings, the FAA mandated in 1972 that cooper vanes to be installed to prevent the opening of the rear door while in flight.

Does this make the pre-cooper 727 the last passenger airliner which had a door (either passenger or cargo) that could be normally opened while in flight without depressurizing the entire cabin?

Small Print: There was a rear cabin, pressurized bulkhead door on the 727 that you had to transit through to get access to the ventral stairways which was in the aft, unpressurized bulkhead. The actual ventral stair door itself was not a "plug" style. Thus the ventral stairways meets the requirement of being able to open in flight (even if you couldn't get there because the rear cabin bulkhead door might not open).

Animated image from wikipedia and cc.


texts: Is having a history of seeing a therapist not allowed for pilots?

texts:
In a recent question someone said:

  I thought about seeing a therapist, but as I want to work at a major company, I don't know if you're allowed to have a history of seeing one.

Is it true that having seen a therapist a bad thing? If yes, why? It doesn't make sense to me.


texts: How can I calculate maximum rate of climb?

texts: By what way and with which variables could you determine a plane's maximum rate of climb per time? If I'm not mistaken, I'm looking for VY.


texts: How to determine the aircraft tail number on a particular flight?

texts: How can one determine the registration number (i.e. N123AA) of the aircraft used on a particular flight, having the date, airline, flight number and city pair to start with?


texts: Is it possible to interchange different of fuels for turbine engines?

texts:
There are a few types of fuel for turbine engines, for example Jet-A, Jet A-1 and Jet-B.

Is it safe / practical to interchange these types of fuel for a generic turbine engine?


texts: Why are the runways on Denver Int'l very separated from the terminals?

texts:
As you can see in the airport diagram the runways are very separated from the terminals:

I've  found a similar question about Schiphol runways and one of them is very separated because of the noise. But at Denver Airport there are no towns or cities near the runways so, what could be the reason?

Source


texts: What are the design goals for NASA's X-57?

texts: There have obviously been work going on prior to the X-57 announcement (see LEAPTech and Joby Aviation http://www.jobyaviation.com/LEAPTech/). However, what does NASA actually think they will achieve as far as specifications after completing the X-57? I have seen the 175 mph cruise at 1/5th the energy cost numbers thrown around, but the real numbers that matter are not stated by NASA. For instance, will the entire aircraft except for the pilot seat be packed with batteries? What is the useful payload? What will be the range on a single charge?


texts: Are there dual pilot planes to pilot myself?

texts:
I understand planes have 2 piloting systems often?

Is there a plane I can demo fly first flight?

I'm interested in saying I have flown and that's it.


texts: New Research: VGs increase lift to drag ratio up to 880%. Does it work for flaps too?

texts:
Aerodynamic Free Lunch: VGs increase L/D ratio up to 880%. Does it work for flaps too?

I understand this research was for a wing without flaps.

I understand this reduction in drag with VGs works only for the alpha range past the max Cl point of the wing without VGs, eg. 8-18 deg, increasing the L/D by 880% at 18 deg AOA as shown in the table and graph below.

Questions:

Would a wing with 20% chord NON-SLOTTED flaps see a similar 84% reduction in drag for each flap setting eg 10,20,30 deg?
Would a wing with 20% chord SLOTTED flaps see a similar 84% reduction in drag for each flap setting eg 10,20,30 deg?
Why does the drag almost stay the same even thought the lift goes up? My intuition is that the VG wing drag value stays close to the 8 deg drag value w/o VGs, as that is the local AOA the wing is seeing due to the VGs, instead of the drag at 18 deg, even though the lift is increasing.  Is that correct?

Article:

Experimental and Numerical Analysis of the Effect of Vortex Generator Height on Vortex Characteristics and Airfoil Aerodynamic Performance
Xinkai Li 1,2,3,* , Ke Yang 1,2,3,4 and Xiaodong Wang 5
1 2 3 4 5
102206, China; wangxd@ncepu.edu.cn
* Correspondence: lixinkai@iet.cn; Tel.: +86-010-8254-3038
Received: 29 January 2019; Accepted: 7 March 2019; Published: 12 March 2019
 Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190, China; yangke@iet.cn Key Laboratory of Wind Energy Utilization, Chinese Academy of Sciences, Beijing 100190, China
Dalian National Laboratory for Clean Energy, CAS, Beijing 100190, China
Graduate School, University of Chinese Academy of Sciences, Beijing 100049, China
College of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing
 Abstract: To explore the effect of the height of vortex generators (VGs) on the control effect of boundary-layer flow, the vortex characteristics of a plate and the aerodynamic characteristics of an airfoil for VGs were studied by both wind tunnel experiments and numerical methods. Firstly, the ratio of VG height (H) to boundary layer thickness (δ) was studied on a flat plate boundary layer; the values of H are 0.1δ, 0.2δ, 0.5δ, 1.0δ, 1.5δ, and 2.0δ. Results show that the concentrated vortex intensity and VG height present a logarithmic relationship, and vortex intensity is proportional to the average kinetic energy of the fluid in the height range of the VG. Secondly, the effects of height on the aerodynamic performance of airfoils were studied in a wind tunnel using three VGs with H = 0.66δ, 1.0δ, and 1.33δ. The stall angle of the airfoil with and without VGs is 18◦ and 8◦, respectively, so the VGs increase the stall angle by 10◦. The maximum lift coefficient of the airfoil with VGs increases by 48.7% compared with the airfoil without VGs, and the drag coefficient of the airfoil with VGs is 84.9% lower than that of the airfoil without VGs at an angle of attack of 18◦. The maximum lift–drag ratio of the airfoil with VGs is lower than that of the airfoil without VGs, so the VGs do not affect the maximum lift–drag ratio of the airfoil. However, a VG does increase the angle of attack of the best lift–drag ratio.

Source: www.researchgate.net › publication › 331712096


texts: Must a CFII be instrument current to provide instrument training?

texts: Can a CFII conduct training for an instrument student in VFR conditions if the CFII isn’t instrument current?


texts: Should I do bachelor first or pilot training first?

texts: I am a student now going to grade 12 residing in Nepal. I am perplexed about should i do my training first  get a job and do bachelor alongside with my job or should I do bachelor first and then training and then get a job.


texts: Why was a complete test flight of Hughes Hercules H-4 (Spruce Goose) never undertaken?

texts: I get that ,the max altitude it was flown to was 70 ft. after its 3rd test taxi.I also am aware that even this was done to prove a point. But,why was there no attempt later on to complete a test flight and to check if it was Air worthy? Was no one curious at all ?


texts: Is it possible for a modern commercial airliner to stop being tracked without substantial mechanical failure?

texts:
I was speaking to someone about the MH370 incident, and they suggested that a hijacker could turn off the device that sends the plane's current position, resulting in the appearance of a catastrophic midair failure.

I assume that such functionality could not be turned off, but I could be wrong. Is there any way that this could be done? Could an aircraft's internal tracking systems be "turned off" midair, and also not be located by external tracking like radar?


texts: What are the off-airfield rules for private helicopters in New Zealand?

texts: I'm a Switzerland-based private helicopter pilot planning to spend some time in NZ. I'm wondering what are the rules there regarding off-airfield landing. Is it possible at all? Is the land owner approval required? Are their any altitude limitations like in Switzerland? What are the typical practices there?


texts: Why is an LPV WAAS GPS approach considered non-precision?

texts: My understanding of precision was both lateral and vertical guidance. If a GPS approach with WAAS provides both, why is it still considered non-precision?


texts: Does runway centerline lighting provide information about distance left before end?

texts:
I asked Does runway center lighting increase runway lifetime? and this video was was mentioned.

I don't really understand the significance and I first assumed centreline lighting in night conditions helped crews know half the runway is done and they don't accidentally overshoot the runway.

But I was explained centreline lighting helps in directional and alignment guidance for the aircraft. How is that possible?


texts: Why don't commercial airliners use variable sweep wings?

texts: I know they're not used in military aircraft because it decreases the stealth factor, but why don't commercial plane manufacturers make variable sweep planes?


texts: What are the rules regarding airlines picking up passengers at stops in foreign countries?

texts: Suppose Air Canada flies from Vancouver to Santiago with a stop in LAX. I am vaguely of the belief that they are not allowed to pickup Americans who wish to travel from LAX to Santiago, but I'm curious to know more about these rules (if they exist). Also, how they apply (or not) internationally, ie. not just in America.


texts: How much data do FDR and CVR generate on commercial jets?

texts:
I'm wondering about how much CVR and FDR data an A320 (for example) would produce and at what intervals.

I believe that there are 4 or 5 voice channel and several sensor data things. I'm trying to get some data on commercial jets. Is there any place I could get some data on this?


texts: How to verify the runway numbers in a systematic way given the high workload during landing?

texts:
I have never had a runway number verification on my checklists because normally the landing checklist is completed and stowed by the time I am on short final and can clearly see the numbers.

However, after seeing that Harrison Ford just landed on a taxiway and I know commercial jets have done the same thing from time to time, I am considering a checklist item. One issue is not just the taxiways, a lot of larger airports and big airfields like Oshkosh have multiple parallel runways with right/left designations so it can get pretty confusing. The whole problem is that normally when I am on final and swooping in everything is happening fast and I do not have available bandwidth to be looking at a checklist, I have to be laser focused on making the landing and watching for traffic.

Any suggestions how to verify the runway in a systematic way given the constraints?


texts: Why do some airplanes have their winglets at different angles?

texts:
While travelling recently a friend of mine noticed that the tips of the wings on some planes were at different angles on the left and the right hand sides of the plane.
Is this a thing and what is the reason for this?

Some googling and searching on this site did not reveal an answer.


texts: Has an aircraft carrier ever assisted a civilian passenger flight? I am trying to find an example of this. It could be as extreme as a small plane landing on aircraft carrier in an emergency. A simpler example would be a civilian passenger plane requesting navigational assistance from an aircraft carrier over VHF communications.


texts: what is the disadvantage of blended wing body ,that they not used to achieve more than subsonic speed?

texts: Blended wings have more efficiency than today's wing design,high lift to drag ratio,more efficiency,less fuel rate ,it have lot of advantages so why not they used for commercial airplanes as well as military aircraft rather than UAV.


texts: Why did wings start to be made with aluminium skin instead of fabric?

texts: Why did engineers start designing planes with aluminium skin on the wings instead of fabric covering? While the force of lift acts on the skin, to my knowledge it is not subject to high stresses


texts: What is the red barb for in the NOAA weather briefing?

texts:
Wind barbs are well-defined symbols, but I noticed in my WX briefing that there are now occasional red barbs in the chart.
The red appears on both the 5kt and 10kt barbs, and sometimes for largest 10kt barb or the smallest 5kt barb.


texts: Would the flyby in this video be illegal under 91.119(a)?

texts:
I was watching this video

             and just curious about the legality. Would it just fall under 91.119(a) operation of an aircraft 'anywhere'


texts: Are there other practical means of 'slowing' down an aircraft, other than parachutes?

texts:
Whenever an airliner crashes, inevitably questions arise as to how can the planes be made safe and ultimately, how can we avoid loss of lives.

Though statistically, modern airliners are safest ever, but due to the nature and outcome of even a single crash, it affects people psychologically worldwide.

Questions like parachutes for planes or even passengers are numerous on this site. For example, I posted this questions after reading this question.

The way I understand, if an aircraft can be slowed down, by means of a parachute, the resultant damgage to human lives would be a lot less. This led me to wonder, what can be other means of slowing down an aircraft, which would crash otherwise.


texts: Do helicopters fly a standard pattern before landing?

texts: How do helicopters approach and land at an airport? Do they use the same general traffic pattern as fixed-wing aircraft?


texts: Do airlines require aptitude tests or other similar tests for new pilots?

texts: Do airlines require pilots to take an aptitude test? Are there any other similar kinds of tests that airlines perform?


texts:
US aircraft carriers mostly use F/A-18 Hornet.
French aircraft carriers mostly use Rafale-M.
Indian aircraft carriers mostly use Mig-29K.
Chinese use Shenyang J-15.
...

None of them are VTOL aircraft.

Why didn't VTOL aircraft achieve much popularity with aircraft carriers?

Why didn't we see many VTOL aircraft in the history of aircraft development?


texts: Why is managing CG (centre of gravity) important?

texts:
Why do people have to worry about CG? Is it primarily due to fuel penalty, or take-off and landing performance, or is it mostly just to keep the aircraft from tipping over during loading and unloading, or other?

As a bonus, does tipping over of aircraft actually occur these days due to improperly managed CG?


texts: Can planes still land during a regionally-diverse ATC malfunction?

texts:
Spoilers for the Pilot episode of Scorpion

   In the Pilot episode for the TV series Scorpion, all major control towers in the greater LAX area are taken out because the firmware is malfunctioning and our heroes need to get a proper version active again, while the airborne planes could not be contacted through any method. They first try to recover a backup version of the software from a datacenter, but that fails. They then contact a salesman on a plane via his antique cellphone and manage to reload the software using a Ferrari and a laptop wired into the plane.
 One of the major plot points was that, because the software was malfunctioning, none of the planes could land safely, even though one of the planes could safely buzz the tower and even get close enough to the ground to make a wire connection to the ground. If they could fly so low, why can't they just land it?

So can a plane land during a complete control tower malfunction? And what is the general SOP in case of malfunctions? I've read both How realistic is the aviation crisis in the recent Spider-Man movie? and What happens to incoming flights when the airport shuts down, but part of the plot was that every airport in the greater LAX area got the problematic malware at the same time, so it's possible that many of those planes had their alternate destination airport also in trouble.


texts: Can you do your PPL solo time in an ultralight?

texts: I've been thinking of getting an ultralight as a low cost way to pursue flying.  And I've been wondering, when my instructor finally signs me off for a solo flight, am I allowed to do that in an ultralight?  And, if so, is there equipment I would be required to have that isn't standard on an ultralight?


texts: How can I avoid downdrafts and icing when crossing the Alps in a small airplane?

texts:
let's say I need to fly from LSZL to LSZP crossing the Alps with a small airplane (C150, Piper Tomahawk,...). How many times a year I could expect to find the suitable weather conditions to do that (both VFR and IFR)?

The main issues I have identified are:

Strong downdrafts near the base of the Alps (-2000fpm). A small plane has a service ceiling of 13000ft: would it be possible to climb high enough to avoid this phenomenon?
Icing: I expect the OAT to be below zero all year, moreover ice could build up even if I'm outside the clouds. Normally small planes are not equipped with boots, or de-icing fluids systems. How can this problem be handled?


texts: Has the construction team of the Northrop Grumann B-2 Spirit made use of the features of the German Horten Ho 229?

texts:
1)
 2)
In the first picture, we can see the German-made Horten Ho 229. See also this video.
The second picture shows the American-made Northrop Grumman B-2 Spirit. See also this video
Clearly, both air wings show a remarkable similarity. The German plane looks much smoother though than the quite linear and edgy American one (is there a reason for this? Hasn't a smoothly formed plane less resistance?).
The Horten brothers, who supervised the construction and came up with the design, had no computers at their disposal like plane designers have these days. Every time some adjustments had to be made to make it fly better. In this BBC article one can read the plane was its time far ahead.
The designers and constructors of the NG B-2 Spirit did have computers and more advanced technology at their disposal to construct a working flying wing which clearly shows much resemblance with the wing developed decades before (maybe in a more "instinctive" way?).
My question is simple (I couldn't find this on the internet}:
Did the people who made the NG B-2 Spirit make use of the information of the Horten Brothers. Did they use the blueprints of the HH Ho 229?
Extra question: Why does the Northrop Grumann have such an "edgy", straight form, while the Horten has a smooth, curved form? Isn't curvature and smoothness better for the aerodynamics?


texts: Why does Turkish Airlines avoid Israel when going to Amman, but not on the return leg?

texts:
(flightaware.com)

Last week I was browsing Flight Aware when I came across a Turkish Airlines flight from Istanbul (Turkey) to Amman (Jordan). I noticed that the flight path clearly makes an effort to avoid Israeli airspace. My instinct was that Turkish airlines had some diplomatic issues with Israel and had to avoid their airspace.

Today I came across this post asking what the busiest Turkish Airlines route is, and turns out that the answer is Istanbul to Tel Aviv (Israel). That made me curious about my initial finding. I posted this as a comment on that thread and fellow user @MichaelSeifert pointed out that the return flight, THY813, flies right over Israel.

This leads me to believe that there are some restrictions on flights entering Jordan. Does anyone know anything about this issue or have other similar examples?


texts: How do rotor tangs lock into wheel keyways?

texts:
How do the rotor tangs lock into wheel keyways? Are there special keys on the outboard wheel half that allow locking the tangs in place?
Also would be great if anyone could provide me with a image of an aircraft wheel from the inboard side looking outboard.


texts:
During the landing flare, the cockpit can sometimes be twenty/thirty feet or more above the rear landing gear, especially with larger aircraft.

(source: valkaviation.com)

In some aircraft, you can hear the system call out altitude when on final, ie "500... 200... 100... 50... etc".

Where does the altimeter measure altitude from? Does it measure from the bottom of the rear landing gear, or from the cockpit itself? How do pilots know when the rear landing gear will touch down?


texts: How does a pilot receive weather information when overflying the oceans?

texts: As the aircraft is too far from antennas and units, how do they be aware of weather changes or weather information along their route, or on the destination and alternate airports?


texts: How much difference in heading/bearing between consecutive legs is "officially" considered a turn?

texts:
While examining FAA's TERPS manual (Order 8260.3D) and PBN manual (Order 8260.58A), I noticed two seemingly contradictory statements.

  TERPS 8260.3D Chapter 14. Departure Routes, 14-3-4 . Construct turning segments when the course change is more than 15 degrees

(emphasis mine)

Whereas in PBN manual, it seems that a deviation of 10 degrees is considered a turn.

  PBN 8260.58A 1-2-5,b,(1)a . [...] Not applicable for FB turns of 10 degrees or less.

(emphasis mine)

Am I missing something. Is there any consistent rule that states when a transition between legs of an Instrument Procedure is considered a turn or a straight flight?


texts: What are the different steps to certify a new aircraft in Europe?

texts: I know that to be allowed to fly an aircraft has to be certified by an agency and that this one is not the same for European or American (for instance) aircraft. What are the different steps that an aircraft designed to fly in Europe has to go through in order to be certified? Proof on the paper of some features? Ground tests (which one)? Flight tests (which one)?


texts: Do airliners like Boeing and Airbus use airfoil variation along the span for their wings?

texts: Airfoil variation will make a significant difference in airflow over the wing, thus proper variation according to the lift profile should improve the overall aerodynamic performance. But by how much? Are major aviation manufacturers using it? I can't find any reliable information on this.


texts: How can I renew my non-current Indian CPL?

texts:
I have not renewed my Indian CPL since 2001 and would like to renew it. what is the procedure as the CAR says nothing about renewing licence below 5700 kgs category.
Since there is no rule what can be done. I am flying regularly on my FAA licence.


texts: What is the aircraft model used in the film "American Made"?

texts: In American Made, what is the model of the white airplane that the CIA presents to Barry Seal (played by Tom Cruise)? He says something along the lines of "the fastest piston twin". Are those continental engines?


texts: On an energy-maneuverability (E-M) diagram how does the shape of a specific excess power (Ps) curve change as thrust is increased or decreased?

texts: Most E-M diagrams for high-performance aircraft show a "dog house" plot with turn rate on the Y axis and velocity on the x axis.  They may also have additional lines for constant turn radius and load factor.  There are also Ps curves that show specific excess power at an given point in the performance envelope.  The Ps curves tend to be shaped like a "rainbow" when superimposed on this chart.  Most curves that I've found only demonstrate performance at maximum thrust (normally maximum afterburner).  However, I'm curious what the Ps curves would look like at 100%, 75%, 50% power, etc.  I theorize that the Ps curves would tend to become flatter and would shift to the left of the chart.  Ideally, I'd like to see a comparison of two charts at different (known) throttle settings (with all other parameters being equal).


texts: Are there any Part 135 (On-Demand Passenger Charter) companies out there that use Aviation Bio-Fuel?

texts:
I was recently approached by a client asking if I can provide charters on environmentally conscious aircraft that run on Aviation Bio-Fuel.

Anyone have any insight on what is required for an aircraft to run on bio-fuel?

Who is implementing the use of Aviation Bio-Fuel in their fleet?

How do I find out which airports actually have Bio-Fueling capabilities?


texts: Is communication with cabin crew or ATC included in emergency checklists?

texts:
In a serious but non-catastrophic situation on a commercial flight (for example, a single engine failure on an A320), I understand that the pilots will follow a standard checklist (from the QRH) to put the aircraft into a safe condition.

My question is - will such a checklist generally include an explicit item to inform ATC, the cabin crew, and/or the passengers, or is this generally assumed to be done as a "standard procedure"?  If it is usually on the checklist, would it always come at the end, or are there situations where ATC might need to know about the incident as soon as possible?


texts: Has a Russian Tu-95 ever had to make an emergency landing in Europe?

texts: Has a Tu-95 Bear bomber ever made an emergency landing in a European country while the flight was on a mission to test the country's defences?


texts: How do the VNAV and LNAV work on the 737NG?

texts:
So, I'm very confused. Im from a Cessna background, no FMC. So, based on my understanding, you could run the autopilot independent of the FMC right? With Speed mode, HDG SEL mode, and V/S mode, am I right or wrong?

And if you enable VNAV and LNAV, the FMC takes over right? But I heard people say you can change the V/S in VNAV mode. How is that possible? I thought the FMC has full authority, and the flight route you filed in the FMC is final?  And does this mean you can also change the HDG in LNAV mode?


texts: Light business jets - how many are sold each year?

texts:
This AOPA article  says

https://www.aopa.org/news-and-media/all-news/2018/october/16/hondajets-get-performance-upgrades

  The company is delivering four to five aircraft a month from its Greensboro, North Carolina, factory, the CEO said. In 2017 and the first half of 2018, the HondaJet was the most delivered light jet in the market. All in all, 92 HondaJets are in service with a 99.7-percent dispatch rate, Fujino explained.

So that's 48 to 60 a year.  What other light jets are available for purchase?


texts: What term is the EASA equivalent of the DER in the FAA safety assurance process?

texts:
When the FAA approves a hardware or software (or mixed) system for use in an aircraft requiring Type Certification, A Designated Engineering Representative (DER) is selected to work with the developers and apply the safety assurance guidelines (or other alternative means of compliance) needed for approval. Although the DER is not the final authority granting approval, de facto if you fail to satisfy the DER you won't get approval, and if the DER finds that all needed guidelines have been met and all evidence is in order, you probably will.

The EASA process in Europe is very similar, but many of the acronyms and terms they use are different, which brings me to the question:

What is the European (EASA) equivalent of what in America we call the Design Engineering Representative (DER)?


texts: Why would maximum fly-time (endurance) not coincide with max L/D operating point?

texts:
This question is motivated by another SE Aviation answer where @Peter Kampf writes the following two useful bits of information:

  Aircraft like to fly near their optimum L/D ratio, where drag reaches
  its minimum.

  Observation aircraft which want to optimize flying time will fly
  slower that what optimum L/D requires, especially if they use
  propellers.

Do aircraft use the majority of their fuel to overcome friction?

I'm trying to understand this more: Why would maximum fly-time not coincide with max L/D operating point?

Is this something to do with the jet engine fuel consumption characteristic? i.e. Does the minimum fuel-consumed-per-unit-time point not coincide with the optimum L/D point? But if your payload is fixed, so is your lift & hence your velocity choice that gives you that lift right?

i.e. For a given payload, lift is fixed. For a given lift, minimum drag leads to max fuel economy? And max economy means max dwell time? What gives.

For simplicity I assume we can ignore the climb / descent / acceleration etc. for now. And only consider the level flight segment at fixed speed.


texts: What exactly are the functions of an aviation headset?

texts: All I know from Google searching is that they provide hearing protection and ATC communication maybe? Do pilots have to attach them or are they wireless? Who can the pilot reach using them?  How much hearing protection does a pilot need? For instance, how does a pilot figure out how many decibels of protection is needed say for a Cessna 172? Must headsets always be worn? I'm interested in knowing all aspects of the uses of an aviation headset.


texts: Why don't we get more user-friendly weather reports than METARs?

texts:
This question is not about how to decode METARs or what software or tools can be used to decode METARs. It is about why we are still using METARs today.

Given that we have smartphones with video messaging capability, cloud services with machine learning today, I struggle to understand why we are still reading METARs:

It is difficult to read. Sure it is not hard to learn, but the fact that you have to learn it means it's not intuitive
It is designed at an age when text are transmitted by telegraph and every character counts
It is trivial to program a parser and render more friendly messages

For me I always feel that METARs are meant for machines; there has got to be something better for pilots which happens to be human. Instead of having this on my flight plan:

  KSFO 111456Z 16015KT 9SM RA FEW012 SCT030 OVC070...

Why not just:

  Station: KSFO

  Time: Mar 11 14:56 UTC

  Wind: 160 degrees, 15 knots

  Visibility: 9 statue miles

  Weather condition: rain

  Clouds: few at 1,200 feet; scattered at 3,000 feet; overcast at 7,000
  feet

  ...

The problem is not about decoding them. Most pilots can read them, and by the time a new pilot completes his PPL training he should have no trouble reading either. The point is everybody around the world is reading them, today, in the 21st century!

I don't know if I'm the only one, but processing the METAR string during flight prep takes a couple of instruction cycles away from my brain (and I have a tendency to check whether the software got it right if I happen to be using one, so I will be processing it anyway, which is a good habit I suppose). I am sure some of that brain power can be better spent somewhere else: reading section charts, route planning, picking an alternate, etc. Scaling this to the global scale? It means every pilot is paying more attention to other things, as opposed to reading coded weather strings which really is the job of a machine. The result? Better flight safely.

So, why haven't we began the move?


texts: Have any commercial airline passengers ever been injured from hypoxia due to a depressurization event?

texts:
This question is inspired by the question "What can I do to save my life if oxygen masks fail to drop down? Is it possible?" One of my first thoughts upon seeing that question was: do you need to do anything, or will you survive regardless of what you do?

Note that I'm not asking about situations like Helios Airways Flight 522, where the crew became incapacitated due to hypoxia, resulting in a crash which killed all on board. I'm wondering if a passenger has ever gotten hypoxia and suffered from health problems (or death) as a result.


texts: What is the German / European equivalent of FAA Order 7110.65?

texts:
FAA Order 7110.65 prescribes air traffic control procedures and phraseology for use by personnel providing ATC services in the USA.

Which documents regulate these aspects in Germany, or, more generally, in Europe?

Please provide also the valid versions of these documents as of the 1st of April 2020.