texts: Why is a canard configuration more Structurally efficient for Rutan's Voyager?

texts:
Firstly, I’d like to kindly request not to mark this question as a duplicate of previous SE question without first reading this, because the approach is different and the previously given answers are merely incorrect.

Background

I found this information in VoyagerEssay.pdf from Burt Rutans website.

EDIT: I am putting this possibly redundant info with the hope it might help better clarify the problem as suggested.

From Burt's own notes.

  The range of an aircraft is determined by three basic criteria: its
  propulsion efficiency, its weight and its aerodynamic efficiency. I
  had to make major improvements in one or more of these areas in order
  to build an aircraft that could fly more than twice as far as any
  previous flight.

Please see "breguet-range-equation" for more info. And this range equation suggests us the range of an airplane is exponentially sensitive to the initial and final weight ratios; and linearly sensitive to L/D and total propulsive efficiency eta.

And as the per the same source, this configuration was chosen to achieve higher structural efficiency.

  The primary reason we were able to double the old record related to
  our success in weight control. By using a new, unusual configuration
  we could place a large amount of fuel at three span-wise locations:
  the fuselage and two large booms at 30% of the distance out to the
  wing-tips. A very light main wing and canard wing provided just the
  amount of structural support for this large fuel mass. The two wings
  supported the fuel-laden booms via their bending stiffness without
  depending on the torsional stiffness of a single slender wing. This
  was Voyager’s secret to success. Its graphite composite structure
  weighed only nine percent of the take-off weight. The fuel consisted
  of 73% of the take-off weight. This phenomenal weight performance was
  the main reason we were able to achieve our goal of true global range.

And of course in return traded off aerodynamic efficiency.

  Regarding aerodynamic efficiency, I was unable to achieve a result as
  high as a typical sailplane since I was forced to use the unusual
  configuration

In this John Roncz presentation, he mentioned this configuration was to solve the problems of having high inertia fuel booms, [~18 mins] but without any specific note on how it resolves into a canard.
As per Mr. Roncz, he appears to suggest this minimizes the bending stresses of the booms. (Please correct me if Im wrong) and note from Burt appear to suggest the config was selected to minimize wing torsional loads.

Question

Can any of you please provide me with an explanation as to why the canard configuration ideally could be more beneficial for this design?

My argument is if he had chosen the second config shown below, he would have gained BOTH structural benefits of canard plus aerodynamic benefits of conventional config.

In my eyes, this is an even better win-win solution but most certainly too good to be true; hence my question.

If possible I would love to see some quantitative answer rather than qualitative but any constructive answer is more than very welcome.


texts: How is the pushback tug connected to the airliner?

texts:
If I understand correctly, there are two way to connect a tug: with or without a bar; and the tug can push back or pull forward the airliner.

When using a bar, how is the tug connected to the airliner? Is there a standardized fixation? Is there any articulation on both sides of the bar?
When using a towbarless tug, the tug lift the nose wheel. How is it done? Is there limitation on nose-wheel dimensions?


texts: Legend for SkyVector's Sectional Chart outside the US

texts: Does anyone know where can I find the legend for the symbols used by SkyVector's Sectional Chart for places outside the US? The US symbols are well documented but other places (e.g. the United Kingdom charts) seem to use a different set of symbols and line strokes for airspace classes.


texts: Could the Airbus A350 be converted into the role of air tanker / be used for aerial refuelling?

texts: Since the A350 is one of the most efficient jets out there, Is it possible that it can be transformed into a fuel tanker for Aerial refuelling?


texts: Can you identify this model of a twin-engine propeller aircraft?


texts: What effect does a direct crosswind have on takeoff performance?

texts: Is the take-off distance increased by a direct crosswind?


texts:
Evacuation procedures after a forced landing recommend directing passengers upwind of the aircraft.

What is the reason why evacuating upwind is better than other directions?


texts: What does the number of white bars in runway's threshold mean?

texts:
At the beginning of each runway there are some white bars.

Does number of bars in threshold mean anything?


texts: What are the main components of the Airbus fly-by-wire system? Is ECAM related to FBW?

texts:
I'm assuming that all commercial Airbus planes use a similar, if not identical, system. Can someone give me an overview of the parts of the Airbus fly-by-wire system?

I've also heard of ECAM. Is ECAM related to fly-by-wire?


texts: Can a commercial pilot rent an airplane and use it for hire?

texts:
Can the holder of a commercial pilot certificate rent an airplane (with a recent 100-hour inspection) from a fixed-base operator and use it to carry passengers for hire?
I believe the answer this is a "NO" since this pilot would be holding out by providing the airplane to the passenger, thus, this pilot would illegally be acting as a commercial operator / air carrier. Basically, the pilot and the airplane would be coming from the same source, even though the pilot doesn't actually own the plane and is renting it from somewhere else.
EDIT: Sorry, yes, I'm asking in regards to US regulations (FAA).


texts: Is the United Kingdom subject to the EASA's authority or the CAA's (Civil Aviation Authority) authority?


texts:
Has there been a recent change in the airspace configuration at KFYV-- Drake Field near Fayetteville AR?  If so, where can we find an official description of that change?

KFYV -- Drake Field airport at Fayetteville Arkansas http://vfrmap.com/?type=vfrc&lat=36.005&lon=-94.170&zoom=10

(Memphis sectional chart, western portion of north half)

A sectional chart dated April 13 2006 shows a class D circle with a large E4 (dashed magenta) extension to the south, but on the current sectional chart (effective March 28 2019) the area projecting to the south is now much smaller and is class D rather than E4.

Has there been a recent change in the airspace here?

If so, what is the official FAA source that describes that change?

I do not see the airspace configuration as shown on the current sectional to be reflected in the August 2018 edition of the FAA's "Airspace Designations and Reporting Points" document ( https://www.faa.gov/documentLibrary/media/Order/JO_7400.11C.pdf ) , or in the more recent amendments given here https://www.faa.gov/air_traffic/publications/airspace_amendments/

The Class D airspace is described on page D-112 of the "Airspace Designations and Reporting Points" document, and the E4 airspace is described on page E-206.  The description matches what I see on the 2006 sectional chart.

Is the current sectional chart simply wrong?


texts: Which is better: a rotor / prop followed by a stator, or contra rotating rotors / props?

texts:
It is all in the title.

I'm interested in power absorbed/used for a given thrust, or thrust generated for a given power (same diameters of course).

Just thrust and power.  Ignore materials, electric vs turbine, complexity of the  contra-rotating mechanism, etc.


texts: How much operating documentation is produced for an airliner by the manufacturer?

texts:
A long, long time ago, when I was a young child, I read in a book or magazine that the 747 weighed 170 tonnes (or whatever) - but that the manuals it came with weighed even more! (I recall the same article explained that the aircraft contained over 100 miles of wiring; it was that kind of article.)

I can well believe that the total amount of technical documentation (design, production, operation, maintenance, etc) associated with an airliner could weigh more than a hundred tonnes.

But, just how much documentation would actually be delivered to the customer? Could it indeed be 170+ tonnes' worth?


texts: What are the implications of Visual Descent Angle Not Authorized (VDA NA)?

texts:
On some non-precision approach plates, there is a VDA/TCH mark. My understanding of it is information-only. If you pass its starting fix at the charted altitude and maintain the given descent angle, the airplane will flying over the runway thresh hold at TCH.

However, I noticed one NOTAM mentions this information is not authorized, e.g. E16 RNAV (GPS) RWY 32 (on Nov 2019).

!FDC 9/9659 E16 IAP SAN MARTIN, San Martin, CA. RNAV (GPS) RWY 32, ORIG-C... GELVY TO RW32: 3.37/45 NA. 1903201729-2103201728EST - (From FAA website on 2019/11/22)

Given "GELVY TO RW32: 3.37/45" is still one spatial path for the non-precision approach, and the LNAV approach is still available. There are no airport elevation and re-defined fix height. So my questions align with,

1) Why am I not authorized to fly "GELVY TO RW32: 3.37/45", if my airplane is capable to maintain descent angle and have runway environment in sight right above MDA.

2) Are there any additional procedures to follow even for flying VDA/TCH at an airport when are authorized?

E16 RNAV (GPS) RWY 32

--


texts: What was the exact propeller geometry of the 1903 Wright Flyer? A modern replica failed the test T = D in a NASA wind tunnel

texts:
Full-Scale 1903 Wright Flyer failed the test Thrust = Drag in a NASA wind tunnel

I have found a presentation about an extensive set of tests done in 1999 on a full scale replica of Flyer I 1903. The plane did not behave well and was not able to produce enough thrust to overcome the drag.

"In the wind tunnel, the reproduced propeller fell short of T=D @ 28 mph test condition when operating at the maximum permitted speed of 340 RPM. These data are being analyzed"

$C_L=C_L(C_D)$ Flyer I replica

Source: Full-Scale 1903 Wright Flyer Wind Tunnel Test Results From the NASA Ames Research Center

Unfortunately, the presentation, also quite explicit, does not give the values of the Thrust, Drag or Drag - Thrust at 28 mph. I calculated the Drag from $C_L=C_L(C_D)$, Lift = Weight (the mass of the airplane is known) and and the surface of the wings. Using a simulator I also evaluated the thrust delivered by some modern propellers, having the same diameter as the ones the Wright Brothers said they had used in 1903, and they deliver enough thrust at 28 mph and 340 RPM.

There should be other more detailed articles, which I can not find, about the same set of tests because they planned the experiments for years and it is expected a lot of data was obtained.

I would be really interested to know either the exact geometry of the propellers to calculate their thrust with a simulator or find somewhere the diagram $Thrust
= Thrust_{340\:RPM}(v_{air})$ corresponding to the tested replica. If you can find such a document please tell me about it.

Anyway at 6 hp / propeller (12 hp in total) I calculated that only propellers with an efficiency well below 50% (miserable even for the standard of 1903) could have failed to produce enough thrust for the Flyer I replica at 28 mph.

Update 1

A Mathcad demonstration which shows that the efficiency of the propellers used by the Flyer I replica should be below 31.2% to fail the test T = D.

Update 2

Another wind tunnel set of tests was done in 2003 on a different Flyer I replica (see: Flying Qualities of the Wright 1903 Flyer:
From Simulation to Flight Test). Also the lift drag diagram for the case "props off" was about the same as the one obtained in 1999, the thrust generated by the propellers at 340 RPM and Q = 2 psf which translates in a 28 mph plane speed, the same as in the 1999 tests, was 80 lbf (36.28 kgf) more than double than the Drag = 17.44 kgf calculated for the 1999 replica. Unless quite different propellers had been used in 1999 and 2003 the 1999 propellers should not have failed the test T = D at 28 mph. It appears that various investigation teams have used propellers with different geometries.

Flyer I 2003 replica - Drag Coefficient, On Rail - Propellers off

Flyer I 2003 replica - Static and dynamic thrust of the propellers two dynamic pressures, $Q = 0.5\rho V^2$. 1) $Q = 1\:lbf/ft^2$ ($V=19.98\:mph$) 2) $Q = 2\:lbf/ft^2$ ($V=28.26\:mph$). $\rho=1.2\:kg/m^3$

Source: "Flying Qualities of the Wright 1903 Flyer:
From Simulation to Flight Test" (AIAA-2004-0105)


texts: How does the safety record of the twin piston Diamond DA-42 compare to the single piston DA-40?

texts:
Its fairly well known that the Diamond DA-40 has one of the smallest fatality rates of any GA plane. The Diamond DA-42 is a twin engine aircraft with a very similar design to the DA-40.

Now, it has been shown that, in general, twin aircraft are not that much safer than single because the added complexity of operation removes the added safety from engine failure. However, the DA-42 is much easier to fly with FADEC control of the engines and a lot of automation.

Is the DA-42 safer than the DA-40?


texts:
When flying the Super Decathlon from the backseat, I can see the manifold pressure (top left corner of the panel) and G-meter (top right corner), and that's it.  This (along with the fact that the guy in the front seat blocks the view of the runway centerline) makes it difficult to get good consistency in landings.

I know that in if your airspeed indicator fails for some reason you can simply keep a little throttle in, fly until ground effect, and then bleed off whatever speed remains, but that's inconsistent and ugly.  I'm talking about being able to hit any arbitrary point on the runway ten times in a row.  I would call that impossible without at least an airspeed indicator, but older, wiser pilots have been doing it for years.

How do I make consistent landings from the (instrument-less) backseat?


texts: I have heard incidents in which commercial aircraft are required to dump fuel in event of an emergency to avoid landing over maximum landing weight. What systems do aircraft have in place to dump fuel? How is a fuel dump initiated from the cockpit?


texts: What is a Virtual Window in an aircraft?

texts:
I heard about Virtual Windows in the Dubai show, but I didn't really got it. What is it?

In a demo, when they opened the shields, I could just see the ground handling before taxing.

Search engines only gave me a patent, but I would rather learn about it laconically.

PS: Found in a triple seven.

I found a video where an english guy mentions them, but he doesn't seem to have a clue about their functionality.


texts: Is there a speed needed to achieve flight?

texts:
Is there a minimum speed needed for flight (universally)? For example, if something was going 10 miles per hour, could it achieve flight? And by flight I don’t mean throwing a paper airplane, I’m talking about the item going to that speed, then flying.

Is there a formula for calculating the speed needed for flight?


texts: What is the stall AoA for the space shuttle?

texts: Once flying as (fast) glider in order to land, what was the angle of attack it would have stalled? I'm really interested in the angle of attack for such wings and not the speed.


texts: What's the reason for "pre-pressurization" of the cabin prior to liftoff?

texts:
I'm reading a Citation M2's Pilot Training Manual, and it says:

  ...When the throttles are advanced for takeoff, the bleed air turns on
  (if not already on for heating), and the pressurization controller
  starts closing the outflow valves to pressurize the airplane. The
  cabin altitude may descend by as much as 200 feet during this
  pre-pressutization prior to lift off.

What's the purpose of the pre-pressurization prior to lift off?


texts:
In the book 'Pocket guide to military aircraft', they use the term 'Fast jet' for a certain range of aircraft.

Is 'fast jet' a common and well defined term used within aviation? If so, how is it defined? In order to be classified as a 'fast jet', does an aircraft have to be able to reach a certain flight level, speed or other performance indicators? Does it need a certain engine type? Must it look in a certain way?


texts: What emergencies or failures should I report to ATC?

texts:
During a flight, what kinds of emergencies or failures should I report to ATC immediately? For what kind of emergencies or failures am I not required to report them?

What is the general rule? Could I have some examples?


texts:
The Pilot Controller Glossary (and other places) define MOCAs as:

  MINIMUM OBSTRUCTION CLEARANCE ALTITUDE (MOCA)− The lowest published
  altitude in effect between radio fixes on VOR airways, off-airway
  routes, or route segments which meets obstacle clearance requirements
  for the entire route segment and which assures acceptable navigational
  signal coverage only within 25 statute (22 nautical) miles of a VOR.

VORs aren’t used in GPS navigation so I don’t understand why there would be a GPS MOCA on a T-Route or Victor Airway.

Even the example given in the Aeronautical Chart Users Guide (p56) has a GPS MOCA below the MEA.

Here’s a segment of a Victor Airway in Florida with a MOCA of 1300 but the MEA for GPS is 3000.

I would think the GPS MEA would be the MOCA or even lower, since VOR reception isn’t required in the first 22 miles. If you fly at the MEA it guarantees that a normal climb will keep you above obstacles when entering the next segment with a higher MEA. But I would think that the MOCA would do the same thing unless there was an MCA. So that doesn’t seem to be a reason.

There are even T-Routes in Florida with a GPS altitude and a lower GPS MOCA. That makes even less sense to me.

Does the GPS MOCA also take into account communication reception—but in that case why isn’t that mentioned in the regular MOCA definition?

If anyone could shed some light on how they come up the GPS MOCAs it would be appreciated.


texts: Why are there full-fledged entertainment systems on aircraft when today everyone has a smart phone?

texts:
Today, many large commercial aircraft have full-fledged entertainment systems, sometimes going as far as putting a personal LED screen in every seat.

Let's just consider the costs of this for a moment:

• weight of the devices and their wiring

• power and waste heat

• cost of designing and approving the system with the FAA

There may be more I missed.

So now let's consider that today, most people (and certainly most people who can afford to fly) have a smart phone of some kind. They will most definitely bring it with them on the flight. And most people will also bring the charger and headphones (or earbuds) with them.

So you can see where this is going. If the airliner wants to provide movies or music, why not just have a jack (USB?) at every seat to plug in your smart phone and get it that way? Or possibly even provide streaming Wifi once in the air (not a true connection to the internet at large, but just as a way to distribute the movies/music). There might still be bandwidth challenges, but surely, surely this is better than a traditional IFE system as it exists today.

Am I missing something?


texts: Which are typical rpm values for aeronautical turbines?

texts:
I wonder which of these has higher or lower rotational speed:

turboshaft
turbofan
turbojet
turboprop

Does anybody know the typical speeds for these kind of engines?


texts: Would the twin engine Boeing Y3 be able to compete better than the Airbus A380?

texts:
The low sales performance of the quad engine Airbus A380 and declining sales of the Boeing 747-800 have largely been attributed to lesser fuel economy of quad engine aircraft when compared to their newer more fuel efficient twin engine counterparts.

The image rendering of the future Boeing Y3 aircraft shows a jumbo size twin engine twin deck aircraft the size of an Airbus A380.

Whether or not a prototype was ever made, in light of fuel economy technology improvements more prevalent and effective in twin engine configurations like the GE9X, would the twin engine Boeing Y3 be able to compete better than the quad Super jumbos and Jumbo respectively the Airbus A380 and the Boeing 747-8?


texts: What prevents DC-9 series aircraft from being reengined with more-efficient engines?

texts:
All DC-9s except for the MD-90\B717 series use old, inefficient Pratt & Whitney JT8D series low-bypass turbofans, even the best of which have a paltry 1.74:1 bypass ratio.  We know that a DC-9 can accommodate a high-bypass turbofan; the final iteration of the DC-9 (the MD-90 series, including the Boeing 717) uses much more efficient engines with bypass ratios in the 4-5:1 range (which is the main thing distinguishing the 90-series aircraft from their predecessors).

Given that we know that a DC-9 is perfectly capable of using a high-bypass engine, and that the kerosene-guzzling nature of the JT8D is the main reason why DC-9s are being steadily phased out of service (as their low fuel efficiency makes it hard for airlines to make a profit from a pre-90 DC-9), why haven't the remaining older-series DC-9s been re-engined with high-bypass turbofans?


texts: What is a TAPS combustor and how does it differ from any other annular combustor?

texts: I found out that the GEnx engine uses a TAPS (Twin Annular Premixing Swirler) combustor. Is it a single or dual annular combustor ?


texts: Why is one of Madera Municipal's runways labelled with only "R" on both sides?

texts:
I was looking on Google Maps satellite view and noticed Madera Municipal Airport in Madera, CA (ICAO KMAE) has an east-west runway labelled with nothing but the letter "R" on both sides. There is no parallel runway. Why the strange marking? Airnav reports it as runway 8/26, so why not label it that?

Composite for both ends via Google Earth


texts: How do you apply to offer WINGS credit for an event you are sponsoring?

texts: Douglas Rotary is sponsoring a fly-in October 3, 2015 in Douglas, AZ at the Douglas Muni. Airport.  How do we apply to get pilots WINGS credit for their training?


texts: Is flying during the day safer than flying at night?

texts:
Is there any correlation between night or day flight time and rate of accidents?

To me it seems that there should not be a difference. If an airplane needs to execute an emergency landing, it has to do it at an airport which is illuminated at night.

However, what if the pilot needs some ground visuals to navigate, for example, because the instrument are not working similar to the Air France Flight 447.

Edit

I only mean commercial airline flights done by planes such as airbus a320/321/330 or Boeing 737-800.


texts: What is the best major to study for a career in propulsion systems design?

texts: I want to be an aerospace engineer but am not sure what to major in. I really want to design propulsion systems. What would be the best major for this and what could I do to increase my chances of being hired?


texts: How do I make a simple model to simulate a banked turn?

texts:
I'm attempting to make a game similar to Ace Combat, and I'm still confused about banked turns, namely the speed of bank turning depending on the aircraft's roll.

Can I assume, for simplicity's sake, that it's something like $Rgy = K * Rz$, where $Rgy$ is the rate of turning on the global Y axis (the banked turn's angular speed), $Rz$ is the roll angle of the aircraft, and $K$ is a constant? And if I can do so, how do I calculate $K$?


texts:
When flying into an area with colder air, how will the altimeter read compared to true altitude?

Air expands as the temperature increases and it compresses when the temperature decreases, shall I expect it is flying to a higher pressure area ?


texts: How is hypothetical max altitude of a helicopter calculated?

texts: How do engineers calculate the hypothetical max altitude of a helicopter if the mass, altitude and length/curvature of blades are known?


texts: Why do multiple planes arrive from the same airport at the same time?

texts:
I'm looking at the Arriving flights page of the Vancouver Airport and in many cases there are several planes coming from the same airport, arriving at the same time, all at the same gate.

Does it count for only one plane and they are affiliated companies?

Here are some screenshots:


texts: Both the FAA and the EASA have decided against using ADS-C in the development of NextGen and SESAR, because of cost, scalability and ease of use. But has ADS-C actually been implemented and used in practice anywhere?


texts: Is it required to report climbs and descents within a block altitude assignment?

texts:
The following is assuming US FAA and IFR.
This question stems from a question on CRUISE clearance. Section 4-4-3.d.3 of the 2021 AIM says that in a CRUISE clearance

Climbs/Descents within the block is to be made at the discretion of
the pilot.

I've never been given a CRUISE clearance, but I have been given a Block altitude assignment before (e.g. 8000-12000). I could climb and descend to my heart's content without telling ATC every time I changed altitude within my assigned block. In fact, I've been voluntarily given a block altitude assignment by ATC just to shut me up after asking for too many altitude deviations for weather.
The AIM says about CRUISE clearance,

However, once the pilot starts descent and verbally reports leaving an
altitude in the block, the pilot may not return to that altitude
without additional ATC clearance.

Some of my fellow pilots interpret this to mean that you must report to ATC when you descend, but the way I read this is that you don't have to report leaving any altitude in a Block until you are finished with that altitude or the block, and once you descend AND report leaving an altitude, then that signifies to ATC that they can assign that vacated altitude or block to other aircraft. However, none of this appears to says to me, that you have to report descending within the block if you intend to climb back up in the block later.
In other words, don't report to ATC that you're descending until you are done with the block. For example, if I'm given 8000-12000. And I start my final descent and I know I'm not going to be climbing back up then I'll tell them Cessna 123 10000 descending 8000. Then ATC can assign the 10000-12000 block.
Questions:

When given a CRUISE clearance (which includes a block altitude assignment from MEA to CRUISE altitude) where does it say that a pilot must report altitude changes (climbs or descents) within the block altitude. If not, then where does it say you don't have to report altitude changes.

Is there an FAA publication that provides more information on Block altitude assignments and Cruise clearances besides the AIM?


texts: Where can I find the flight path data for the Russian spy plane that flew over the US on 9 Aug 2017?

texts:
Multiple news outlets are reporting that a Russian spy plane, a Tupolev Tu-154M, flew past various locations in the U.S.

Politico is reporting that the plane was seen on a flight-tracking website in Washington D.C., Bedminster, NJ, and Dayton, OH.

Is there a way (maybe on the flight-tracking website Politico mentions) that I can look up historical data on this flight to see when it was in each place and what its flight path was?


texts: Has FAA published any A-RNP STAR or A-RNP / RNP AR DP SID?

texts:
After reading FAA's Performance Based Navigation Strategy 2016, I tried to search for already published Departure Procedures of RNP specification. I could only find some that require RNP-1, even though they seem to be rare, like STAYY ONE (KSNA airport).

My question is, are there any SIDs of A-RNP or RNP AR DP specification or STARs of A-RNP specification officially published, at least as far as FAA's charts are concerned?


texts: Why doesn't the 737 have a fuel dump nozzle?

texts:
I was watching a documentary on aircraft incidents which mentioned that the 737 does not have the facility to dump fuel. Instead they're required to fly in circles to burn off excess fuel in an emergency.

It strikes me as a little odd, as someone without detailed knowledge of the 737-series' fuel systems, that the world's most popular passenger jet doesn't have this capability.

What was the design consideration/reasoning for this?


texts: How to determine when a non precision approach does or doesn't have a Final Approach Fix (FAF)?

texts:
I am curious to know how to know for sure whether a non precision approach has/doesn't have a final approach fix by looking at its plate. From what I can see, a Break Cloud and/or NDB procedure might not have a FAF, but I am not 100% sure.
Can anybody give me an example of a NPA with FAF and NPA without?

These are two examples of NPA plates from South Africa.


texts: What is the business purpose of scheduling two separate flights on the very same route with 5-10 minutes separation?

texts:
As in question. I have noticed, for example, that Berlin-Tegel has TXL-CDG route served by both AirBerlin and AirFrance with exactly five minutes separation. First plane takes off at 09:50 and second one at 09:55. I have also noticed that the same rule goes for longer routes, i.e. LHR-SYD goes with around 20-40 minutes separation, served by both Qantas and British Airways.

Can someone explain me a business or economic reason for doing so?

Why these two planes are not scheduled with a bigger separation? I.e. 2-3 hours or even half of day in case of long routes? Wouldn't that assure bigger chance or getting more customers? If route interest is big enough that two planes, near each other, needs to be scheduled, then why simply one airline don't use a larger airplane and the other one schedules its own flight 2-3 hours later or so to capture "other part of day" travellers?


texts: Is Cessna 150 with incorrectly marked ASI airworthy?

texts:
I've looked a bit at the CFRs trying to determine this for sure, but haven't found a clear answer..
One of the Cessna 150s that I rent from the local FBO had it's airspeed indicator swapped out four or five months ago..  the new indicator, in addition to having the low end of the speed range super clumped together so it's difficult to see the accurate reading near the stall speed, is clearly MARKED incorrectly for the airplane that it's in.  The most obvious example is the white arc -- on the ASI that they installed, the top of the white arc is at 80mph, when this Cessna 150M should have the top of the white arc up closer to 93mph.
I know it's not a super huge difference, and I feel that I can fly the airplane safely, but it made me wonder whether it's airworthy with such an obviously incorrectly marked ASI in it.
Thanks!


texts: How to find out how many aircraft depart/land from a country per day?

texts:
I am trying to get the following information. I would like to know for each day how many aircraft have taken off and departed from a specific country. This information should be up to date and possibly have also some historical time series as well (for example the last month).
I know i could get such information by paying some services like Flight Aware or FlightRadar24 but I need to do it for free.
I tried OpenSky but the API doesn't offer much information (just time, lat/lon, origin).
Do you know a possible way to gather such information? It doesn't need to be machine readable as long it has the info.

Thanks in advance.


texts: Does skin friction drag decrease with velocity?

texts: The wings of subsonic planes have usually a very low surface area and aspect ratio as big as possible. However, in supersonic aircraft, wings with more wetted area (e.g delta wings) are used. Is this because skin friction decreases with speed or because in supersonic flight this type of drag is no longer the main concern?


texts: What is Transponder Code 2000 actually used for?

texts:
On What is the significance of a squawk code? @DeltaLima gave a fairly concise answer. In it he listed several 'standard' codes used for things like emergencies.

Also in the list was Code 2000, for which he included the description:

  Used when entering a Secondary Surveillance Area and no code has yet been assigned

So, if I'm in the US, under VFR (code 1200) and I enter a Secondary Surveillance Area, I automatically change to Code 2000? Why wouldn't I have already been given (a specific) designator?


texts: How common are 400Hz supplies in aircraft?

texts:
I understand that 400Hz, 26Vrms power is found in a lot of aviation equipment. But how common is it? Is it in every plane and every instrument or is it restricted to certain sectors, like military, commercial, or private planes?

Is it used a lot in ground applications to power aviation equipment, like in a workshop/lab setting?

The reason I ask is that I'm trying to gauge interest in a small 400Hz, 26Vrms power supply for the benchtop (plug it into regular 60Hz 120V power). From what I can see, these are hard to find below a few thousand dollars.


texts: How are crews managed after a diversion (far from hub)?

texts:
While reading one of the reports of flight diversion, I started thinking about how airlines manage aftermath of the diversion especially for long haul transatlantic flights.

Many of the reports say airlines provides a replacement plane. Replacement plane flies to the diversion airport, load up the passengers and continue.

If the original flight is full, what happens to original crew? Working with the assumption that new flight has new flight/cabin crew and there is not enough place for all.

If the airport is at significant distance where the replacement comes from or still has to fly significant distance, it's possible that replacement flight crew might run out of flying time.

Do they provide multiple sets of crews - one to fly to diversion and one to fly to actual destination.


texts: Is this an accurate method to showing how the correct Decision Altitude/Height for an approach has been determined?

texts:
Here's my method of summarising how the decision altitude/height for an approach was determined:
DH/A =
The highest base altitude/height from the list below +
Altimeter Pressure error +
Altimeter Temperature Error +
Company Operational Procedures Additions

Base altitude/height:

OCA/H
System Minima e.g. ILS 200ft, VOR/DME 250
OCA/H per aircraft category
(Otherwise) Published approach DA/H
Minimum A/H to which the approach aid can be used
Minimum A/H in the Aircraft Flight Manual

Instrument Rated pilots will need an understanding of how the DA was determined, they may be examined on it in theory tests and skills proficiency tests - though whilst actually flying the approach they will use the plate DA.
Is this summary correct, or how would you alter it?


texts: Is it legal to give flight instruction in my own airplane without 100 hour inspection if doing it for no charge?

texts:
14 CFR §91.409(b) states

  ...no person may give flight instruction for hire in an aircraft which
  that person provides, unless within the preceding 100 hours of time in
  service the aircraft has received an annual or 100-hour inspection and
  been approved for return to service in accordance with part 43 of this
  chapter or has received an inspection for the issuance of an
  airworthiness certificate in accordance with part 21 of this chapter.

What if I want to give instruction to a friend or family and they are not paying me to do it? Would I be exempt from having to do a 100 hour inspection?


texts: What would happen if thrust reversal is accidentally deployed during a flight?

texts:
Is it possible to deploy the thrust reversal, in the cruise phase of a flight? And, if they are accidentally deployed, what could be the possible consequences?

As the cruise phase requires a lot of lift, so certainly the impact would not be very desirable..


texts: Why don't we have yokes that look like steering wheels?

texts:
This question came across my mind when I was thinking about cockpit design vs car design: why don't we have yokes that look like steering wheels?

The first advantage I can think of is more gestures to hold the yoke. You can hold a steering wheel in many ways, e.g. 2 & 10 o'clock, 3 & 9 o'clock, top, bottom, one hand, both hands etc. And one can still pull or push the yoke even if it's circular.

Secondly, in most (if not all) of the yokes, full aileron deflection is achieved when the yoke is rotated approximately 90 degrees. Would it be beneficial if it's 180 degree instead, allowing more fine control?


texts: Are the holes inside the engine nacelle used for uniform intake of air?

texts:
I read the post here: What is the function of the holes in splitter plates?

My question is, what are those hole looking things inside the engine nacelle?

It seems reasonable to me that as air enters the intake slower air would accumulate towards the outboard portion of the engine nacelle due to the shape of the leading edges. You want the air to enter the blades uniformly so you could add these pinholes which would remove the slower moving air. This would lead to more even distribution of faster moving air and subsequently better engine performance.

Am I tracking correctly?

Edit: here’s another picture


texts: What are the reliability statistics for modern jet engines?

texts:
What is the actual numerical reliability statistics of the modern, large-aircraft, commercial turbofan engines available today?

e.g. How many running hours can we expect a failure after? Are there empirical or projected MTBF statistics?

How is credible MTBF established for a new engine model?

Is there a significant difference in the failure rate between engine models or manufacturers?

I was motivated to ask by this snippet on another answer on SE Aviation:

  In the days of the 747 regulations required at least 3 engines if you
  ventured more than 60 mniutes of flying time away from a suitable
  diversion airport (in case the second one also failed). However as
  reliability of engines increased this got extended with ETOPS
  certificates.

How rapidly has engine reliability improved? Do we have a time trend of reliability numbers?

Why do modern airliners have only two engines?


texts: Does the cockpit have an alarm to warn about fuel leakage?

texts: Is there any indication to the crew of the aircraft about any potential leakage of fuel from any part of the plane?


texts: Why is the empennage design of this Lockheed 1049E so complicated?

texts:
Photo.

What is the reason for making the empennage of this Lockheed L-1049E Super Constellation's design look so complicated with two vertical horizontal stabilizers? In my understanding, the more components installed, the more the weight of the airplane will be, and as a result will put more load on the engines, especially if there will be more actuators required. Do all the horizontal stabilizers have controllable surfaces? What is the reason for making the horizontal and the vertical cross each other, and not attaching them at their tips (marked with yellow and green circle)?

Edit: I corrected the question on the body from with two additional horizontal stabilizers? to become with two additional vertical stabilizers? as supposed to be as I marked in the picture.


texts: What is the procedure when being vectored for an approach and ATC allows you to pass through the final approach course?

texts: If you are on a heading, being vectored to intercept final on an instrument approach, and it appears that you will fly through the final approach without being cleared to intercept it, what should you do?


texts: Is this explanation of adverse yaw correct?

texts:
It is explained here that adverse yaw is caused by the difference in induced drag due to the difference in lift being generated by each wing.

I've also seen a couple of websites (including Wikipedia) that argue that this explanation is wrong. They explain the cause of adverse yaw as being the change in the direction of the lift vector during a roll, or what some refer to as the "twisted lift" concept. They usually have a diagram like the following:

source

The twisted lift explanation discounts a difference in induced drag due to a change in the amount of lift. They contend that lift and drag remain the same but they twist in different directions. The descending wing has a slightly higher local AoA and the rising wing slightly lower. Since lift is perpendicular to the local airflow the lift vector rocks forward on one wing and aftward on the other.

This explanation seems flawed to me.

First of all, in the diagram they show the force on each wing being the same. If that were the case the aircraft wouldn't roll at all, it would ONLY yaw.
Second, the vector of lift being perpendicular to the airflow is correct, but that is really just an arbitrary division of the total aerodynamic force. The yaw axis of the plane is not dependent on airflow. It would be dependent on the portion of the force vector parallel to the wing chord, aka the axial force. As shown in another question, depending on a number of factors the force vector in relationship to the wing does not necessarily move forward with an increase in AoA.
I can't come up with solid numbers, but trying to figure this out for normal flight speeds it would require a very fast roll to even make a 1° difference in local AoA. I ran numbers for a 3° per sec roll at 120 KTAS on a 36ft wingspan (C172) and came up with a change in AoA of about .27°, and that Is only at the wingtip. It would decrease the closer it got to the fuselage. It doesn't seem like it would be enough to cause a significant change in vector and a resulting yaw moment. Or at least it would be secondary in magnitude to the difference in the drag due to reduction of lift.

Since the changes in lift are being created either by changing the effective camber of the wings (ailerons) or by altering the trailing edge flow (spoilerons) rather than a change in AoA I don't think it's quite so simple to predict that the direction of the aerodynamic vectors will necessarily move in opposite directions as this theory assumes.

If this explanation is correct can someone show me what I'm missing?


texts: What is typical thrust to braking force ratio for a passenger airliner?

texts:
Is the ratio fairly constant across aircraft types, sizes and powerplants?

I'd like to ignore the reverse thrust component, since that's not available at the same time as forward thrust.


texts: Is there a standard EASA checklist for auditing Part-145 organizations?

texts: Which document is the reference for preparing an audit checklist for auditing an approved Part-145 organization?


texts: Is it possible to determine a rotation speed (Vr) using other known V-Speeds?

texts:
Is it possible to come up with a good estimate of rotation speed using other known V-Speeds?

For example: if I know a plane has a Vs @ 55kt. and a Vy @ 75kt, is there a reasonable method to use to come up with a safe rotation speed?

This is a general question. I'm not looking for an exact rotation speed calculation (unless one actually exists, of course).


texts: Is it legal to land when an airfield is reporting low IFR due to fog with a visual approach?

texts:
Suppose you are on an IFR flight plan and are coming in to land at your destination.

The weather at the destination is reporting 600RVR due to dense fog.  The fog isn't very high as you can see through the fog while on approach and can see the approach lights and part of the runway lights.  The weather above the fog layer is VMC. The lowest visibility for an ILS approach that can be executed by the pilots is 1800RVR.

Can the pilots accept a visual approach even though the airport is reporting IMC?
Are there other factors that should be considered on an approach like this?


texts: If DME is required, why have non-DME minima?

texts:
I was looking at the ILS or LOC RWY 9 at KJZI today and I noticed that it had lower minima for when you can identify an intermediate fix (YOCUB).  That made sense, but the entire approach requires DME.  So, if that's the case, why even bother having non-DME minima?

Both of the missed approaches require DME.  Under what circumstance could you shoot this approach but your MDA would be 520?

Here's the current plate: http://155.178.201.160/d-tpp/1609/05354IL9.PDF


texts: What are the advantages of using DC electric power over AC, as e.g. done in the EMB 135/145?

texts:
In this question I can see the advantages of using AC electric power over DC in large aircraft. However, Embraer decided to produce a "DC aircraft": the ERJ 135/145.
What are the advantages of such a DC power system over the more commonly used AC one?


texts: How can I pay for flight school in the UK?

texts:
I want to apply for the British Airways future pilot programme. However, it costs £125,000. The biggest loan I can get is £20,000 so where am I supposed to get the rest of that money?

I've heard people telling me that you can get a sponsorship, but I've looked online and cannot find any sponsorship deals because it's all self funded.


texts: What are the definitions of elevator angle of attack and critical angle of attack?

texts:
Angle of attack is the angle between the chord line of the wing to the direction of relative wind. So angle of attack helps the aircraft climb.

Then what is the angle between the chord line of the elevator and relative wind? Because if I am not wrong, by pitching the elevator up, the wing of an aircraft is subjected to the 'angle of attack'.
When you say angle of attack exceeds the critical angle of attack, is it because the elevator is pitched up thus creating wider angle between the chord line and the relative direction of the wind?
In the Air France 447 accident, the PF kept saying, keeps the wings level. What does it mean? How can the wings be leveled when the angle of attack is so high? Does keeping the wings level mean reducing the angle of attack to zero?


texts: How do I keep a C172 straight on the centerline during landing/rollout?

texts:
During rollout upon touching down, I'd often find myself veering off the runway centreline to the left. Every time I input rudder, I have this feeling that I am getting pulled out of the turn (while that is normal just like turning round a corner at high speeds in a car), and that the aircraft might just flip over. But you see I know my limitations of the car, and that it won't flip unless I yank the steering wheel.

My instructors tell me to just simply keep my feet active, but it's the fear of too much input that will cause me to lose directional control of my aircraft.

Upon touching with my main wheels, to maintain centreline, should I just really apply rudder without fear, even though I feel, and visually believe, that I am going to flip over?

What correct techniques should one apply to keep the aircraft straight during the rollout?


texts:
I  have read that pilots only taxi on 1 engine to save fuel.  Which engine does a twin engine jet such as a 737, 777, a320 or similar use to taxi? Left or right, or does it vary by pilot or some other factor?

On 4 engine jets such as a 747 or a380 pilots use 2 engines. I assume its a matching pair, inner or outer.  But again, which pair?


texts: Why does placing one hand on the head track stabilize you during turbulence?

texts:
At 0:40, Lufthansa Capt. Joachim Schwarzenberg advises

"Whenever we get turbulence and that can always be the case during 11 hours 40 on
such a long flight - that is also the flight time -
The safest thing to do while in the cabin
is to be one with the plane.
That means if you can just support yourself on the the head track, then you are
with one hand, firmly connected, it's a straight line to the floor and you
can hold yourself really well.

If you just hold onto the seats like that,
you will always be levered out and fall back down. So just remember this,
with this you even have one free hand with which you can perhaps
maneuver the cart a bit.

What's the physics behind this? Please explain in simple English. I never studied physics.


texts: Are there fees for international flights crossing through another country's airspace?

texts:
When an aircraft flies over another country are there fees associated with such flight? I am thinking particularly of international airline flights, though this might also apply to flights with the same country of origin and destination that transit another country's airspace.

Are there fees for flying through another country's airspace in general?
Are there fees for flying through the airspace associated with an airport in another country?


texts: Do crew need visas when landing at airports in countries other than their own?

texts: If the crew never leave the plane, have they really entered the foreign country? What about if the crew leaves the plane, but not the airport? How do crews of international flights keep up with all of the visas they may need?


texts: What is your responsibility when a distraught pilot is on frequency?

texts:
I found the recent SeaTac incident with a suicidal pilot frightening. I myself remember being in very bad places mentally, and it got me to wonder what I should do if someone is on frequency, making dangerous maneuvers, and clearly has lost all hope and interest in life.

I looked through FAA guidelines and ICAO standards prior to posting this, and the only conclusion I could make is there is only an IMSAFE for you, and not for others.

But in the age of very realistic flight simulators, aviation can seem like a simple, beautiful, fun, and quick way to end one's life. If I am witnessing this, audibly on frequency and / or visually, what do I do? IMSAFE, but how about them?


texts: How does pitot tube shape affect indicated airspeed?

texts:
Air flow over wings and engine inlets greatly changes due to a number of factors, such as atmospheric conditions, speed, and the design of the surfaces. On some engines you can see mist behind the leading edge of the nacelle in front of the fan, indicative of various pressures resulting from the shape of the edge. In the same way I would guess that the shape of the pitot tube would affect the indicated airspeed- possibly at higher speeds or with a wider edge less air would enter the tube, giving an incorrect reading to the pilot. So how do various shapes affect the indicated airspeed? How about fast aircraft such as the blackbird VS common commercial aircraft VS slower aircraft like a small Cessna?

simulated airflow over standard pitot tube:

1:


texts: What is the average number of flight hours that US private pilots require before passing their checkride?

texts:
It's easy to find comments and claims online (including on this site) about the average number of hours that's required for a new US private pilot to pass their checkride. Some are very precise - 67 hours seems popular - but no one appears to have any actual data to support their statements.

This comment is typical:

  We aren’t sure that 67 hours is the actual average. You can find as
  low as 55 and as high as 85 as the national average. A quick Google
  search found a dozen different answers to the average flight hours.
  None of the sources seemed authoritative. The FAA doesn’t seem to have
  a published number.

It's quite surprising (to me) that the average number of hours is so mysterious. Checkride applicants have to report their hours in the IACRA application process anyway, so presumably the FAA has the data. And it would be a very useful piece of information for schools and pilots to have for planning/budgeting purposes. In fact, I would expect part 141 schools in particular to have very detailed records on their students' hours, and perhaps even use them as a marketing tool ("get your private certificate in 10hrs less than the national average!").

But despite all that, there's no official, reliable number that I can find. So, what is the average number of flight hours from zero to passing the checkride?

Details:

Number of flight hours required to successfully pass the initial private ASEL checkride
Data from reliable sources only, i.e. FAA or a credible third-party study that identifies its sources and methodology
FAA private ASEL ab initio candidates only (no add-on ratings)
Part 61 and/or 141


texts:
After having watched the rather horrible yet fascinating F-16 avoiding multiple SAM launches:

I'm left wondering why he doesn't increase his speed? There are, however, some moments when he's pulling rather high G's where he must have given it some more throttle to sustain any speed at all. Does he need to preserve fuel to get back? Or is it better to maintain somewhat lower speed to have a better turning radius when avoiding SAMs in an F-16?

I understand this is basically asking for an entire lecture in how to avoid SAMs, and I'm trying my best to refrain from doing so. I will keep it to a few specific questions:

Assuming he has the fuel to do so, should he have increased his speed, full afterburner?
Is it possible to see in the video, if chaff/flares are deployed?
Was it wise of him to reduce his altitude by as much as he did, or would he have been safer higher up?


texts: What time window size the Eurocontrol's IFPS considers when comparing the EET informed by the airline and its own calculated EET?

texts:
Excerpt from IFPS Users Manual Ed. 22.0 (chapter 34. PROFILE CALCULATION/ROUTE ANALYSIS):

In addition, whenever present in a message, the estimated elapsed time(s)
(EET) shall be used by the IFPS for profile calculation, together with the
total elapsed time (Item 16B). Prior to using the EET information, the IFPS
shall validate it against its own calculated EETs allowing for the provided
EETs to be within a pre-defined window around the EETs as calculated by the
IFPS. In the case the provided EET information is found to be outside this
window, the message shall not be invalidated. In this case the IFPS shall
retain its own calculated EETs.

What is the size of the aforementioned pre-defined window?


texts: What is the bag for on a passenger oxygen mask?

texts: We may all be familiar with the part of the cabin safety briefing where they say that, in the event of a reduction in cabin pressure, oxygen masks will drop from a compartment above our heads, yadda yadda, the bag may not inflate. What is the purpose of the bag?


texts: Why does the cockpit have windows, is it a structural design burden?

texts: Instead of cockpit windows could they have just screens displaying what is happening using a camera? Is it for any useful purpose? Is it a structural burden or is it there for psychological purposes?


texts: Why does fuel consumption decrease with increasing aircraft altitude?

texts:
I have a chart where the thrust ($F$) and the thrust-specific fuel consumption (TSFC) are plotted against the aircraft flying speed, for several altitudes (i.e. sea level, 3000 meters and 11000 meters). This is for a generic turbojet.

I don't know the source of the image, I apologize for that.

At the left, we see that the thrust decreases with altitude. At the right, we observe that the TSFC actually decreases with altitude as well.

However, I think this is counter-intuitive. I understand that $F$ decreases with altitude, since density (and therefore mass flow rate) decreases when the airplane goes up.

What I don't understand is that the TSFC, defined as: $$\text{TSFC}\equiv\dfrac{\text{fuel mass flow rate}}{F}$$ decreases with altitude. In other words, the higher we fly, the more thermodynamically-efficient the airplane is. How does that happen?

From a pure mathematical point of view, it doesn't make sense that TSFC decreases with altitude since, following the aforementioned formula, $F$ is decreasing, which leads me to think that the fuel mass flow rate diminishes with altitude faster than thrust.

In a nutshell: why does the TSFC decreases with the flying altitude, having the last equation into consideration?


texts: Is a class B endorsement required for a Private checkride?

texts: I was just wondering if a Class B endorsement was required for a Private Pilot Check-ride in the US?


texts:
How does the voice in landing phase figure out the altitude from the runway? Is it reading the altitude from altimeter or totally separate system?

How accurate is the reading?

Where is the reference point for altitude measurement? is it from landing gears?


texts:
I know there are busy airports without control towers, and the converse is also true. There is a process for an airport to acquire a control tower. Sometimes, airports want to have their own control tower.

Is there some activity level where an airport would require a control tower for safe operation? Or does air traffic control exist simply to reduce risk?


texts: What is the current state of the practice regarding surveillance and surveillance data integrity?

texts:
I am experiencing difficulties in finding out exactly how air traffic surveillance works in practice, and more specifically what is done to verify the integrity of surveillance data.

ADS-B and other "modern" surveillance protocols (i.e., protocols relying on data package exchanges, squitters or interrogations) are  mostly transmitted in clear-text. The cybersecurity community has been claiming for a decade that there is a high risk of bad data injection which could be catastrophic. Security experts imply that ATC experts are too focused on safety, that they lack a cybsersecurity mindset, etc. The ATC community, on the other hand, has claimed that security experts don't understand the domain well enough to be able to gauge risks, saying that multilateration is always there to evaluate the integrity of ADS-B messages in case of doubt, saying that surveillance is not only these protocols but also voice communication, acars, etc. What I want is not offend either party and get a view as holistic as possible.

Most of what I have found is from EUROCONTROL, deliberables from projects 15.04.05a and 15.04.05b. Typically, this is what it says:

Ground stations capture ADS-B traffic, potentially verify the data using WAM reports, potentially verify the data using other GS reports (not shown on the figure but I think I read it somewhere), then send the data to an SDPD, which can also use WAM reports as well as radar data to check the data. There can be multiple SDPDs exchanging data for even more verification and data fusion. Meanwhile, there are multiple data integrity check, such as angle of arrival measurement, power measurement vs range correlation, etc..

Then, I read that there is also multilateration possible using ADS-B squitters and TDOA with the so called Mode-S BEAST protocol format that provide nanoseconds precision for the timestamps instead of the initial millisecond.

So, what is the real, current state of the practice? Is the EUROCONTROL schema I mentioned above is the norm now and fully deployed, or not at all? What did I miss? Thank you very much.


texts: Airliner headlights flashing alternately

texts: I live in Portland,Oregon.  I watched a large jetliner coming into the airspace heading to the airport.  The red,green and tail lights were normal. But the headlights were blinking alternately.  I have never seen that in all my years watching the sky. Is there a reason for the alternate blinking?Emergency onboard?


texts: Where can Cirrus Aircraft VisionJet Oleo Struts Material and Dimension Specifications be found?

texts:
I am looking to get hold of Cirrus Aircraft VisionJet Oleo Struts Material and Dimension Specifications. Can anyone point me to or share where I can obtain these details. So far, I have been able to get general specifications at the following link.
https://cirrusaircraft.com/aircraft/vision-jet

Thanks.
Vedanth


texts: Can a VFR flight follow the same route of an approved IFR route (such as those found on Forefight Route Adviser) using waypoints and Victor airways?


texts: What is the current state of regulation regarding VTOL aircraft in the LSA category?

texts: With quite a few concept designs in progress, I am curious what the current FAA regulations are regarding vertical takeoff and landing vehicles in the light sport aircraft category.


texts: Why do we check Idle operation with carb heat on during a Cessna 172 run-up?

texts:
I understand this is to “check our engine is still operating at idle”, but can someone explain this more in depth?
Like why wouldn’t it?


texts: How does an aircraft recharge its batteries?

texts:
I assume aircraft have batteries that power up all electronic devices on board. But how are these batteries recharged? When the aircraft is on the ground, it can be connected and recharged in the airport, but mid flight? Is there a way to charge the batteries in the air ?

Next question, bit trickier: how many devices must be plugged by the passengers (via USB) and how long it takes to drain all energy on board of a 787 ?


texts: Can radar detect a small flying device with MEMS microengines?

texts: I have seen some MEMS micro engines and some micro turbines and I would guess they can be attached to some payload to fly. Is it possible for commercial/military radars to detect those micro flying devices?


texts: How does a pilot tell passengers to prepare for severe turbulence without causing panic?

texts:
At the start of a flight, the pilot of an aircraft often talks about the expected weather on the flight path, and tells passengers if there is to be some turbulence during the flight.

How does a pilot explain that there will be severe turbulence to their passengers without inciting panic?


texts: How does flight control surface authority change with AOA?

texts: I am working on semi-realistic (let's just call it "believable") flight simulation component set for a game engine. One of the topics that I tried to research but could not find reliable information on is the authority or effectiveness of flight control surfaces over AOA. I would prefer to see some graphs or some approximate math expression. I've found more or less enough information on other topics (e.g. lift coefficient over AOA) but I cannot really come up with reliable information (even just theory) regarding flight control surfaces. Gut feeling tells me that they would probably behave similar to wing, but on the other hand elevators should really not lose much authority even past stall AOA.


texts: What is the result of increasing number of propeller blades on the same engine

texts: For example Rotax 912. We can meet this engine with 2 and 3 propellers mounted. Or compare airplanes equipped with engines with pretty the same power output i.e. C152 with Lycoming O-235 - 110 HP and 2-blade propeller versus AT3 with Rotax 912 - 100 HP and 3-blade propeller (also both engines have similar max propeller RPM (Rotax has reduction gearbox)). I know that increasing number of propeller blades alllow better power absorption, but what does it change if the engine has pretty low max power?


texts: What is a G-Check and what are the differences relative to other checks?

texts:
Tried looking for a definition on wikipedia for a G-Check. The wikipage only mentions A,B,C,D checks.

Any ideas what a G-check exactly is? I think I found an article stating it is a 7500 hr major inspection. What is considered a major inspection relative to a minor?


texts: Would it be feasible to build a jet fighter plane based on a wooden construction?

texts:
I read about the de Havilland Mosquito recently and that it was a quite successful British bomber in WW2 due its lightweight wooden construction. As far as I understand it, usual planes at that time were built mainly with metal parts already, thus heavier than the Mosquito and hence uncatchable for them. Furthermore it was too fast for getting hit by heavy anti air, namely the German 88mm cannon.

With this traits of a wooden construction, I wonder if it is feasible to build jets mainly of wood and give them a boost in speed. I have doubts however that the wooden construction is stable enough for resisting the hefty g-force mid-air while flying in mach 3 speed.


texts: In the B737, does an IAN NPA require that the G/P is 3° or can the G/P angle vary?

texts: For an IAN Approach to be recognized and work in a Boeing 737, does the Approach G/P need to be exactly 3° or can it vary?


texts: What are the benefits of using thick trailing edge flaps?

texts:
I had been reading in numerous articles (see this answer and this one) that there are advantages of using thick trailing edge flaps. In these articles it kept on coming up that Airbus uses thick trailing edge flaps also for certain reasons but I couldn't understand them. Could someone please explain?

My main question is about the aerodynamic aspect: Why do the flaps have to be made thicker?


texts: How can I calculate the angle of attack of an airfoil?

texts: Can someone provide me a general algorithm to compute the angle of attack of an airfoil, and some theory along with it?


texts: Is it possible that as the Reynolds number increases, a laminar bubble increases in extension?

texts:
I'm studying the Benedek 10355 airfoil (Plot), which should be a profile used in air-controlled models.
While I was carrying out a boundary layer analysis, I realized the particularity that I have placed in the title.
By making an incompressible analysis at Re = 500,000 and alpha = 2 deg, the profile has a laminar bubble on the upper surface (H index which diverges from 2.5 to 4 and then falls to 1.4, negative friction coefficient and plateau of the pressure coefficient) and then it also looks like a bubble on the lower surface.
In this last case, the H index starts from 2.5 reaches about 3.5 then drops to values of 2.5, a sign that the boundary layer separates but there is no turbulent transition. The friction coefficient assumes slightly negative values.
For Re = 1e6, alpha = 2 deg, the extension of the bubble on the upper surface decreases, while the bubble on the lower surface increases; H starts at 2.5 goes to 4 then drops back to 2.5 (so once again there is no transition on the belly).
A Re = 8e6, no bubbles, either on the upper or on the lower surface.
What is the cause of this abnormal behavior on the lower surface? It happens at every angle of attack, at every Reynolds.
Thanks to those who will be able to help me!


texts: Do steam-gauge VSIs compensate for altitude?

texts:
A Vertical Speed Indicator indicates rate of altitude change. Traditional VSIs use a calibrated leak to measure the rate of pressure change, and therefore the rate of altitude change.

However, pressure does not change uniformly per altitude: in a standard atmosphere, air pressure at 0 MSL is 29.921 inHg, and at 1000 MSL is 28.856 inHg: a 1.065 inHg difference. But 10,000 MSL is 20.577 inHg and 11,000 is 19.791 inHg: a .789 inHg difference. A calculation suggests that a VSI calibrated for sea level and climbing at 1,000 ft/min would indicate 739 ft/min at 10,000 feet.

The airspeed indicator has a knob to calculate true airspeed based on altitude and temperature, but the VSI has no pilot-accessible controls. Glass panel instruments would presumably handle this automatically, but is there any correction for altitude in a steam-gauge VSI?


texts: Is it legal to install a TACAN receiver on a civilian aircraft?

texts:
It is legal to use the DME from a VORTAC station (see Is it possible for a civilian to use a VORTAC station? for details), but is it also legal to use the TACAN for bearing determination?

This would probably require different equipment, which is not typically installed on a civilian aircraft (see Why doesn't civil navigation equipment support TACAN? for details). But the answers to that question do not mention whether or not it is legal to install and use this equipment.


texts: Why do turbofan blade tips exceed the speed of sound while prop tips should not?

texts:
It seems that the tips of the fan of a turbofan engine can and do break the sound barrier:

  The GE-90 has a fan diameter of 3124 mm and a rotational speed of 3475 RPM. Their circumferential velocity is d·π·57.917 = 568 m/s or Mach 1.67 at sea level and ISO atmosphere.Peter Kämpf's answer

While, on a propeller driven aircraft, it seems that having the prop tips exceed the speed of sound is a bad thing - Can turboprop blades break the sound barrier?

Why is it that exceeding the speed of sound is acceptable in one situation but not the other?


texts: How soon can I start my turn after reaching the missed approach point, when missed approach procedure calls for a climbing turn?

texts:
If the missed approach procedure only calls for a climbing right hand turn, at what altitude after reaching the missed approach point (MAP) can I initiate the turn on a precision approach that takes me down to 200 AGL.

Some missed approach procedures say, for example, climb straight ahead to 1000 then climbing right turn to 3000, but some just say climbing right turn to 3000.

Is it documented anywhere that in this situation you can immediately start your climbing turn from the DH (or MDA on non-precision approach)?


texts:
It is very common today for planes to land on snow (for example, in Antarctica). How are planes kept in control with so little friction against the ground? What is the procedure to perform this kind of landing? How much extra distance, on average, does an aircraft cover by landing on snow, compared to landing on dry pavement? (Video)

4 US Air Force Hercules aircraft at Willies field, Antarctica Source


texts: What constitutes a flight review for the purposes of eligibility for a remote pilot certificate under 14 CFR 107.61(d)(2)?

texts:
An applicant for the Remote Pilot Certificate who already holds a pilot's license can forgo the knowledge test required by 14 CFR 107.61(d)(1) if they have a current flight review. The regulation states that an applicant must be able to demonstrate aeronautical knowledge by satisfying one of the following conditions:

  14 CFR 107.61(d)

  (1) Pass an initial aeronautical knowledge test covering the areas of knowledge specified in §107.73(a); or

  (2) If a person holds a pilot certificate (other than a student pilot certificate) issued under part 61 of this chapter and meets the flight review requirements specified in §61.56, complete an initial training course covering the areas of knowledge specified in §107.74(a) in a manner acceptable to the Administrator.

14 CFR 61.56 specifies that a flight review is:

  (a) Except as provided in paragraphs (b) and (f) of this section, a flight review consists of a minimum of 1 hour of flight training and 1 hour of ground training.

  [...]

  (b) Glider pilots may substitute a minimum of three instructional flights in a glider, each of which includes a flight to traffic pattern altitude, in lieu of the 1 hour of flight training required in paragraph (a) of this section.

  [...]

  (f) A person who holds a flight instructor certificate and who has, within the period specified in paragraph (c) of this section, satisfactorily completed a renewal of a flight instructor certificate under the provisions in §61.197 need not accomplish the one hour of ground training specified in paragraph (a) of this section.

Are these definitions to be understood as the definition of a flight review, or might the following flight review exemptions also count for the purposes of §107.61(d)(2)?

  (d) A person who has, within the period specified in paragraph (c) of this section, passed any of the following need not accomplish the flight review required by this section:

  (1) A pilot proficiency check or practical test conducted by an examiner, an approved pilot check airman, or a U.S. Armed Force, for a pilot certificate, rating, or operating privilege.

  (2) A practical test conducted by an examiner for the issuance of a flight instructor certificate, an additional rating on a flight instructor certificate, renewal of a flight instructor certificate, or reinstatement of a flight instructor certificate.

  (e) A person who has, within the period specified in paragraph (c) of this section, satisfactorily accomplished one or more phases of an FAA-sponsored pilot proficiency award program need not accomplish the flight review required by this section.

For the purpose of initial certification under §107(d)(2), is a flight review to be understood strictly as the training defined by 14 CFR 61.56 (a), (b), or (f), or do the exemptions to the requirement for a flight review—14 CFR 61.56 (d) or (e)—also count as a flight review?


texts: How should a Traffic Control Tower notify aircraft that their frequency just changed?

texts: What is the policy for ATC towers to notify aircraft the frequency they broadcast and monitor on has changed? How do they do it, if radio isn't available (because they just changed their frequency)?


texts: Why doesn't Stratolaunch have connected tailplanes like it has connected wings?

texts: As a complete layman, the design of the Stratolaunch airplane, especially when reminding myself of its size, seems too flimsy, in that the only connection between the two fuselages is the center wing. Apart from apparently trusting their materials and connections, what might the reasons have been for  Dynetics engineers to not also connect the tailplanes? Also, are there no aerodynamic disadvantages to having that many more trailing edges (if that's the terminology used)?


texts: Is a flying wing optimal for high altitude craft?

texts:
One of the biggest problems with flying wings is their sheer thickness, which creates excessive drag.
However, since high altitude craft need bigger (and thus thicker) wings anyway, and since weight us a bigger issue with these larger wings, and is addressed with the flying wing, would a flying wing not be the best option for accommodating the required payload volume for minimum surface area and weight extreme altitudes?
Yet high altitude aircraft up till now have used the tube and wing configuration. Why?


texts: Is it possible to increase available take-off distance for a seaplane by turning?

texts:
In the video below an A5 had an accident after takeoff. The final cause of the accident seems to be a sharp increase of AOA above stall.

Do sea planes have an alternate technique for takeoff from tight spaces. Let me draw what I mean:

So in case 1 take distance available for T/O is not enough. Is there a procedure such as in case 2, where you use one side of the lake to accelerate to some speed and then turn to main leg to complete the takeoff?


texts: Is an FAA Part 121/135 checkride conducted under Part 91 or Part 121/135?

texts:
Is a checkride which is required in order to qualify a pilot for 121 or 135 operations itself conducted under Part 91 or Part 121/135 rules?

For instance, is a first class medical required in order to be PIC for the line check required by 135.299 or is only a second class medical required?  Is a fully qualified 121/135 SIC required in order to do the flight (in non-revenue service), or could it be done with an SIC qualified only for Part 91 flights?

I understand that in order to act as PIC of a Part 121/135 flight you need those, but what about for the actual checkride?


texts: Do USAF fighter jets go supersonic over land?

texts:
Does the US Air Force operate supersonic fighter jets over land?

I heard that the FAA banned supersonic flight over America due to the shockwaves creating loud booms and breaking windows on the ground, therefore the Concorde only operated over the Atlantic Ocean.

However, is the US Air Force allowed to operate supersonically over land? How about in training missions, or drills, or a real event? Did they go supersonic during 9/11?


texts: What is this helicopter (and probe) in the film "Act of Valor"?

texts:
In the film Act of Valor, two helicopters are used to airdrop troops and their boats onto a river. (Clip here.)

Firstly can you identify the aircraft?
Second, what is the extremely long probe on the front? It looks to be half as long as the actual helicopter!

My initial guess would be some type of Chinook and refueling probe but that's purely guessing. Can anyone verify or correct?


texts: Why can the aircraft not turn on pitot heaters itself?

texts:
There have already been some posts about pitot heaters: when to turn them on/off, why not leave them on etc.  I don't want to go over that.

I am an engineer, so I'd like to ask:  if the flight management avionics detect an out-of-bounds disagreement from the pitot transducers, and the heaters are off, why not turn them on, in addition to whatever other warnings etc. they already perform?

An ECAM message about turning on the heaters could be made and, if the pilot explicitly wants the heaters off for some reason, s/he can instruct the computer or pull a breaker, so overriding the software.


texts: How does the efficiency of a piston aircraft change with altitude?

texts:
Turbine aircraft are more fuel-efficient, per mile, the higher they fly and this is for two reasons:

drag depends mostly on indicated speed, but the same indicated speed corresponds to higher true speed, and
the lower temperature increases efficiency of the engine.

Now both effects should also apply to piston-engined aircraft. Plus

spark-ignited engines are more efficient with open throttle, which again occurs near operating ceiling.

So I would expect piston aircraft to also fly as high as possible, and most piston aircraft should have no problem to get to at least 10,000 ft (where supplemental oxygen is not needed yet). But in various stories and documents I notice even long flights are often made much lower. Below 5,000 ft.

So is there actually some reason why piston-powered aircraft would be more efficient at lower altitudes? Or any other reason to prefer flying low?


texts: Is it possible or has anyone explored the possibility of capturing static electricity for supplying electrical loads on an aircraft?

texts:
I am wondering if it's possible to harness static electricity generated on the skin of the aircraft to supply power for system loads? Has anyone ever undertaken a project to achieve this?

One reason the question came to mind is that all aircraft I've ever seen have static dischargers for the purpose of dissipating it.


texts: Why do some airplanes have vertical strakes?

texts:
A lot of different aircraft have vertical or near-vertical fins below the empennage, or above the empennage and attached to the front of the vertical stabilizer.

What purpose do these devices serve?


texts: Are some tail wheels made out of solid plastic?

texts: Are any tail wheels on small planes made of hard, rounded, plastic-like material?


texts:
How can a NACA2312 airfoil or similar have a camber location from 30 to 39% without a change in airfoil name?

Was fooling around in javafoil, and noticed I could go from 30% camber to 39% camber, without the NACA number of the airfoil changing!! What the heck?

What name is used to differentiate NACA2312 with 30% camber location and NACA2312 with 39% camber location?


texts: Is training and pay different for cargo and airline pilots?

texts:
Do cargo pilots receive different training than airline pilots? Are there notable differences in salary or other benefits?

My assumption is that since cargo pilots do not have to deal with passengers, passenger emergencies, or bear the responsibility of passenger lives, they may have less training and/or earn less than their airline counterparts.


texts: When calculating the lift coefficient,should I use only the lift provided by wings, or also the net upward forces of the entire aircraft?

texts: I'm preparing a wall force analysis from an aircraft at different angles of attack that resulted from a cfd simulation, so I can plot the lift & drag polars. For the lift coefficient, should I only pick the wing surfaces to obtain the lift and drag forces or all the airplane's surfaces for the net forces? The fuselage and the wing fairings have positive lift, so I'm a bit confused if I need take them into account.


texts: Is it possible to stall a stationary helicopter through excessive collective input?

texts:
I understand that helicopters can suffer from "retreating blade stall" where the retreating side of the rotor has low airspeed and stalls in a typical way that airplane wings stall. This happens when the helicopter is underway.
By contrast I am interested if it's possible to stall in a hover or at very low speed, with normal rotor rotation speed, by pulling up too hard on the collective controls, generating an excessive angle of attack for the blades. Is it impossible because of the lever effort that would be required? Are there any safety systems that prevent it? Is it simply impossible to dial in enough collective to cause the blades to stall, even with the lever pulled all the way?
If it is possible, how do pilots know how much collective input is excessive and could cause a stall?


texts: How should operations be conducted at a towered airport that is in uncontrolled airspace?

texts: How should operations be conducted at an airport with an operating control tower that is in Class E (controlled) or Class G (uncontrolled) airspace? Is this topic covered in an FAA publication such as the Aeronautical Information Manual (AIM) or Pilot's Handbook of Aeronautical Knowledge (PHAC)?


texts: What is the difference between flap load relief protection and overspeed protection?


texts: Proportionally, what is more affected by a hot and high takeoff - a electrically driven propeller or a turbofan?

texts:
My assumption would be the electrically driven propeller would be less affected compared to turbofans at high altitudes and take off as although the air would be less dense at these ambient conditions, the electric motor itself should be unaffected. In a turbofan my assumption would be that both combustion efficiency in the core and propulsion efficiency by the fan would be negatively affected.

Is this assumption correct?


texts: I’ve always heard about the dreaded ramp check. What does it actually entail?

texts: What happens during a ramp check? How likely are you to experience one? What happens if they find something wrong? (A major and a minor example if you don’t mind)


texts: Why did Boeing remove the engine chevrons on the 777-X?

texts: From the most recent renderings on Boeing's site, it looks like the engine chevrons found on the 787, 747-8 and 737-Max have been removed from the 777-X. Is there a good reason for this?


texts: What does the code FU1FU2FU5 mean in this metar?

texts:
In their METAR, CYPK reported ... 25SM FEW037 SCT050 OVC250 21/15 A3016 RMK FU1FU2FU5 DENSITY ALT 400FT.

Since it's quite smokey out, I would have expected a simple FU in the weather section after visibility.

I'm wondering what FU1FU2FU5 is about. According to the remark format at http://meteocentre.com/doc/metar.html it should be "layer type and opacity in oktas". Is this just the way to say "sky covered by smoke"?


texts: How do insurers apportion responsibility when airliners collide on runways or taxiways?

texts:
Here's an ATC recording of Virgin and Egyptair aircraft clipping wings at JFK.

Generally, what happens next with regard to sorting out responsibility after a low-speed collision that results in damage to commercially-operated aircraft? (I'm talking about a return-to-gate type of collision where passengers are inconvenienced, rather than a serious evacuation-style incident.) There seems to me lots of factors, for instance:

The captains are in charge of their aircraft, but what if ground controllers gave them poor instructions?
When a parked aircraft were damaged by a moving one, the former might seem the innocent party, but what if it were stopped in the wrong place?
It's possible that an airport itself might have listed incorrect information about its taxiways that leads to a collision.

In automobile accidents, its the insurers who would sit down and come to some agreement, but there's not really an equivalent of the airport in such circumstances. And the stakes are quite high - repairs and delays might be very costly to an airline.

I presume there's always some sort of regulatory investigation, but their prime concern I would think is to stop it happening again, which is not the same as agreeing responsibility and liability. The question is: how do insurers decide who ends up paying, for what is almost always a very expensive error?

 source


texts: Is a smartphone required to control a DJI Phantom 2 Vision+?

texts:
Not sure if this is on-topic here, as the official guidance seems a bit vague.

Anyways, I've got a relatively simple question.  I'm considering purchasing a Phantom 2 Vision+, but am a little unclear about what options there are in terms of controlling it.  Their website makes a big deal about being able to set waypoints (using an iPad/mobile app) and have the quadcopter operate as an autonomous drone.  And that's useful for certain things, but it seems like it would be more fun to control it directly by remote.

Judging from the video here, it does appear that the quadcopter ships with a remote.  But it also looks like you're expected to stick an iPhone/smartphone onto the remote?  Is that a requirement or just an optional extra?

Is it possible to fly the quadcopter without using a smartphone/mobile app (using just what's included in the box)?


texts:
I was looking through my virtual radar logs one of the days and found this "glitchy" ADS-B behavior.  I am almost 100% sure that this is not due to my antenna or setup since two independent different radars confirmed this weird behavior from FlightRadar24.  Also A/C before and after this one did not exhibit this behavior.

Does anybody have any thoughts as to what may be happening???
Why is the "skew" at seemingly same angle?  Is that anything?
In light of MH370, does this happen often, how reliable is that GPS data?

Tail # N657UA
Boeing 767-300
Typical route between EGLL and KORD

Time of occurrence is approximately: 3/16/2014 6:09pm CST

I have also verified FlightAware is ALSO showing the same weird glitch.

See below "yellow" highlighted airplane:

Same A/C from FlightRadar24:

UPDATE:

This seems to be related to THIS aircraft.  The explanations given (GPS->INS->GPS switching) still applies in my opinion, but wanted to give another screen shot.  Here it is today (3/30/2014) and again displaying this behavior - should their maintenance department be alerted to adjust their GPS antenna??


texts: Why are the flaperons on the 787 located so far in-board?

texts:
Why are the flaperons positioned in between the outboard and inboard flaps (see 2nd picture)? Why not have them located as far outboard as possible to achieve maximum roll authority? I would think the order would be more efficient if the main flaps were both inboard, followed by the flaperons, followed by the ailerons. Thoughts?

In a previous post "How does the particular piece of flap behind an engine on a B777 work?", Peter Kampf explains the flaps would have a gap b/w them when extended because they extend perpendicular to the  hinge line and the trailing edge is non co-linear. However, the 737 tackles this problem just fine (see 1st picture) so I don't think it fully captures why the flaperon is placed where it is on the 787 and 777.


texts: Why was the Vulcan bomber used for the Falklands raid?

texts: There is a lot of information about this complex operation. But can anybody explain why they chose to use an aircraft? They could easily shoot cruise missiles from a ship or ballistic missiles from a nuclear submarine. The easiest and quickest option would be just to shoot an ICBM directly from the UK using a conventional warhead. Just put the coordinates in and task done. No risk to anyone! I think the UK had all the needed technology by that time.


texts: How wide is the cone of confusion above a VOR and NDB?

texts:
I saw in book that the cone of confusion of VOR is 40 degrees, and NDB is 50 degrees of each side! Isn't it too much?
Maybe it's a mistake, or old information(book printed in 2004)
Clarify please:
What is the real amount of cone of confusion of VOR and NDB?
What should I do when flew above VOR/NDB (in cones) in terms of navigation?


texts: Is there an FAA-published handbook for Aviation Physiology?

texts: The FAA has many handbooks, but I don't see one in the list dealing with aeromedical or physiology information.  Does such a handbook or advisory circular exist, or is this information only available within other handbooks such as the PHAK?


texts: For jets, how can we show that 1/2*ρ*V^2 is equivalent to 1481.3*δ*M^2?

texts:
In Roskam's book, we find the following relationship given for climb performance in jet aircraft:

  Thrust requested = $D$ = $C_d \cdot (1/2 \cdot \rho \cdot V^2) \cdot S = C_d \cdot (1481.3 \cdot \delta \cdot M^2) \cdot S$

How can we show that $(1/2 \cdot \rho \cdot V^2)$ is equivalent to $(1481.3 \cdot \delta \cdot M^2)$?

SOURCE:
Author: Jan Roskam
Title:  Airplane Aerodynamics and Performance
Paragraph "9.2 CLIMB AND DRIFT-DOWN PERFORMANCE OF JET AIRPLANES"


texts: What minimum radio communication equipment is required in a homebuilt aircraft in India?

texts:
Let's say I am building a single seat aircraft for flying in one's own country(India). What should be minimum set (Not only from compliance prospective but to have core set of communication for security and safety reasons with ATC or other receivers ) of things I must have on my aircraft?

Background : We are planning to provide this set of Radio systems for Hobby Aircraft builders.

Update : As per the answer, It is cleat that one do not need to have radio system always in the flight.


texts: The original design for the F4F Wildcat was as a biplane, but with the -2 model, it was redesigned as a monoplane. I am wondering if the -1 model was ever actually built, or did it remain as a blueprint only?


texts: What happens to incoming flights when the airport shuts down?

texts:
In Die Hard 2 terrorists take over an airport's ILS and landing lights on a snowy night (visual landing is impossible) and start making threats essentially holding the planes hostage.

The tower immediately sends incoming flights away to the diversion airports and "rack and stack" those already in the landing holding patterns. They also notify the pilots what happened mentioning that after the crisis is over they will start landing planes in order of fuel emergency and that radio may go dead later. Later in the movie the planes in the air actually start running out of fuel and one actually tries to land in the fog.

What is the protocol when you are a pilot in that situation? Do you just turn to your alternate when you have been circling around for 30 minutes (the "Final reserve fuel" for commercial jets).


texts:
I am currently working on a personal single seat, piston aircraft that I would fly myself and I am currently in a bit of conundrum when it comes to my wing design. In this project, I assigned us in 2 basic groups. The guys that work on the chassis and the guy (me) that works on the aerodynamic surfaces. Namely wing, surface controls, tail and such. It is a standard pull configuration aircraft, tricycle landing gear. My problem here is that I am kind of undecided when it comes to my airfoil of choice, so I thought of giving the forum a go and see if anyone can illuminate or inspire me.

As of now, http://airfoiltools.com/airfoil/details?airfoil=naca643618-il has been my choice, but maybe I am starting to think that other options could be better so let me write here a few specifications that could come in handy regarding the aircraft.

The main body will be build of steel tubing covered either in Aluminium or fabric. This will be the final choice once we calculate how much lift we can actually produce.

The wings and other surfaces will be made out of carbon fiber. I will be the one mainly working on this, and they will be attached to long solid cuboids spanning from one tip of the first wing, through the body and all the way to the tip of the second wing. The shape and dimensions of these cuboids will be determined through a FEA after we have the correct wing profile (so we can play with the variables afterwards or maybe even find better solutions). The wings will either be attached with rivets to the cuboid or with standard well shaped bolts. TBD.

The aircraft is planned to be mostly used at not so great speeds. If we can achieve a takeoff at 16-20 m/s with flaps on it would be fantastic. I would not like the top speed to be anything great either. I mostly would use this in very good still weather to cruise around the fields.

I can afford having an airfoil that is a bit thick, but would like to manage the turbulence that would be created by boundary layer separation in high thickness and/or camber foils. Maybe I will modify a bit my final selection.

The wing will have flaps, in fact it will be a flap that extends at around 35% of the total span of the wing. It will be a modification of the slot and Fowler flap (a sort of optimized approach that mixes both) whose final geometry will of course be dependent on airfoil selection.

P.S : I use Fusion 360 for modeling, Autodesk CFD to calculate the total lift of the full 3D modeled wing/aircraft.


texts: Did the Soviet Union build any commercial jetliners?

texts: I read about a Wikipedia article regarding the Soviet Union's Tupolev 114 which was comparable to the time's jetliners, and brought up the question: Did the Soviet Union build any jetliners for commercial use (i.e, airlines, firefighting).


texts: Can an aircraft at 10,000 feet have sea level pressure in the cabin?

texts:
Right now at my university we are busy with a project for designing a conceptual aircraft. Our aircraft is in the CS-23 range, this airplane is a small cargo aircraft with the option for carrying injured passengers (so like an ambulance aircraft).

Our aircraft will have a cruise height at 10,000 ft. We want to make this aircraft pressurised but our question is therefore, is it possible to pressurise the aircraft from inside below the normal 8,000ft. So for example, we are flying at 10,000 ft but we want to have the inside pressure having the same as on sea level if that is possible, or is it only possible to pressurise the inside at 8000ft.

Thank you in advance.


texts: Is it legal to drop/shoot paintballs from an airplane?

texts:
My brother and I are big into paint balling and aviation, and we've often wondered if it would be legal/possible to use an aircraft in a large scale paintball match?  Mainly to drop paintballs, or perhaps even bags of paint, onto participants to simulate air support.

A few questions then, to cover this fully:

Is it even legal to begin with?
Assuming it is legal, what is the
recommended way to do this?  Plane size? Configuration considerations?
Lastly, is it legal to shoot back at the
plane?  Or is that just wildly unsafe?

I know, it's kind of a broader question, but I was hoping to get the entire answer in one place for ease of access to the answer.


texts: Why can't you operate packs on HIGH during take-off, approach and landing on a 737-800?

texts:
It's in the FCOM Limitations Chapter and I think that these phases are critical phases of flight and I don't want to reduce my engine performance by purposely creating a high demand for bleed air from my compressors.

Just want to seek some inputs on whether my chain of thought makes sense.


texts: Dead reckoning navigation: gyromagnetic compass, how it is stabilized?

texts:
I am studying aircraft navigation systems, as what concern autonomous navigation a compass is obviously essential, but magnetic compass is not reliable in short term maneuvers due to accelerations so it has to be stabilized by a directional gyro. What i don't understand is how the gyro is connected to the compass and stabilizes it.

In modern airliners is this device still used ? Is there an electronic substitute with no mechanical gyro (a part from GPS system) ?


texts: At what point during a long flight do commercial airliners have the best gas mileage?

texts:
This question has several parts that are interrelated, and I didn't want to split it up:

Considering that several tons of fuel are consumed during a long haul flight which requires lift to be reduced as the flight progresses, do pilots do this by changing wing geometry, altitude, speed or all of the above?

Is this done automatically or manually?

What is the optimal strategy if you want to minimize fuel costs?

Having chosen the optimal strategy, is the latest phase of the flight where the airplane weighs least necessarily the one that gets the best gas mileage, or is there a minimum at a certain intermediate airplane mass during the flight?


texts: Can I log my military training time as PIC, if I have a PPL?

texts:
It's my understanding that instrument and commercial training time can be logged as PIC, after you have a PPL.  I received my PPL in a standard C-172.

I was about to go through and log all my military training time (in the T-6 and T-38) this weekend, and was wondering if I can log all that as PIC?

This questions specifies that you must be be rated in the category and type to do so.  I'm not really sure what that means.  Of course I don't have any FAA ratings other than my PPL in the 172.

So, can I log my T-6 and T-38 time as PIC for my civilian records?

Thanks!


texts: What's the difference between setting auto brakes to MAX vs. RTO in Boeing Aircraft?

texts:
On Airbus aircraft, before taxiing and before take off, pilots turn auto brakes to MAX.

But on Boeing aircraft, they will set auto brakes to RTO.

Why does Boeing not use auto brakes MAX instead of RTO?


texts: How hard is it to fly a US-registered private jet over Cuba?

texts:
I know that commercial airlines have airspace passage agreements that allow them to fly over Cuba, but what about private jets? Is it easy for a pilot of a US-registered private jet departing from Miami to get an overflight clearance from Cuba? What is the procedure?

I am specifically asking about an overflight, not a landing. In other words the pilot wants to fly over Cuba en route to some other destination in South America.


texts: What is the difference between side-by-side vs under-cockpit engine intakes?

texts:
What is the main difference between these two engine configurations?

What are the differences between planes that have the intakes below the cockpit as compared to those who have them on the sides?

What are the aerodynamic differences?

How does this affect the speed/radar signature/maneuverability of the aircraft?

These two configurations are used for almost every existing type of small military aircraft, be it a fighter, an interceptor, ground attack or a bomber - why so? It would be interesting to know why some aircraft have the configurations that they do.


texts: Why do Vx and Vy coalesce at an airplane's absolute ceiling?

texts: I'm struggling to figure out why that is the case. I'm trying to determine why the best angle of climb speed equals to best rate of climb speed at the absolute ceiling on airplanes.