texts: Where can I find the various operating limitations of the ATR 72-500? Is there any document that lists them?


texts: Why do some back course operations use normal sensing?

texts: So the LOC/DME-E approach to KASE lists for the missed approach course to use the I-PKN localizer, but then there's a note 'course outbound is normal sensing'.  Does that mean that in effect, this particular LOC is installed 'backwards' so when flying away from it you get normal indications?  How common is this?  Only for LOC-defined missed approaches?


texts:
I'm trying to identify this plane from an old family photograph.  Is it possibly  a DH4?

The tail number doesn't bring any success (well, at least not that I can find).
Any info would be much appreciated.


texts:
I think most of us know how lift is created. Air is deflected downward because of the shape of an airfoil.

How long does downwash last, is the air going to flow downward forever or will it climb back up to leveled degree? If so how long would it take for the air to get back on its normal flow path, which is not downward?


texts: Can a pilot fly through a restricted area while flying on a Victor Airway?

texts:
For example if you look at V 23-165-597, from Seal Beach CA to Ocean Side CA, you will notice that it goes through restricted area for Camp Pendleton (R-2503A & D):

I was trying to understand what is the rule as far as ATC Clearance to enter those Airspace or any other Airspace in general when you are on those Victor Airways.

Where can I find the FAA rules about these Victor Airways?


texts: Why this formula says jet engine is efficient at any speed?

texts:
Wikipedia gives the following equation for the efficiency of the jet engine, here:

$$\eta_p = \frac{2}{1 + \frac{v_e}{v}}$$

Where V is the aircraft speed and Ve is the exhaust speed. It is backed by some reference to the book I have no access to so cannot clarify what do they want to say by that.

I am still deeply puzzled, how it could be the efficiency increases all the time with the increase of the aircraft velocity, even after it exceeds the exhaust speed many times. I think I have read somewhere that the efficiency declines and not keeps growing after the aircraft speed approaches exhaust speed.


texts: Is a controller at a NFCT required to have an FAA physical? If so what class?

texts: Is there a mandatory requirement for a Tower Controller working at a Non-Federal Control Tower (NFCT) to have a current FAA medical certificate?  Is a Class III sufficient?


texts: Is it possible to use multiple primary radars to determine an object's location in three-dimensional space?

texts: My question is this: if, for example, I have multiple radars across an area, tracking a particular airborne object, can I use the returns from the radars to determine the geographical location of an object in three-dimensional space (its x-y-z coordinates)?


texts: How common are emergency landings for airliners? Is there really more than one per day at Heathrow?

texts:
I've just found an article on one of Italy's most popular newspapers, the "Corriere della Sera", which states that emergency landings are far more common than is normally believed: according to it, at Heathrow there's at least one emergency landing per day. I find this number incredibly high. Is that true?

The article (which is more a collection of "quick facts") doesn't specify the source. I've turned to Google for further info, and the only result I've found is an article by The Telegrpah, which states that the average at Heathrow is slightly above one per week. Even assuming the Corriere journalist wanted to report that figure but got confused and accidentally wrote one per day instead of one per week, it still sounds very high.

An article on abc7ny.com (no idea how reputable that site is) mentions 66 emergency landings at JFK, 50 at Newark and 34 at LaGuardia over a 20-weeks span, from February to June of 2011.

On the other hand, the answers to these two questions on Quora indicate that emergency landings are very rare.

So, if we only consider airliners, how common are emergency landings really?

As pointed out by UnrecognizedFallingObject in a comment, it depends on what is meant by "emergency landing". Is there a commonly accepted definition? If not, since we have to draw a line, I'd say a Mayday counts for sure, and I'd also include a Pan-Pan. Below that, I think we can ignore it.


texts: Can a non FAA CFI (EASA for eg) sign off a high performance endorsement on an FAA PPL certificate?

texts:
I have an FAA PPL cert, flying in the UK. Can a qualified EASA CFI sign off a high performance endorsement on my FAA certificate.
Thanks


texts: Why is Python used on aircraft although it may not be certifiable?

texts:
I recently had a discussion with people who were active in the aviation industry and told me that one of the main languages/tools they use is Python.

On the other hand I have always known that people avoid C++ or eg Linux due to certification reasons for avionics. Certification is also one of the reasons you don't see AI and computer vision in C++ on aircraft. Yet, those people use Python all the time.

I didn't have (and never will have) the opportunity to ask why and for what they used it. Could someone explain why and for what people would still use Python although it may be very difficult to get it certified?


texts: How does a pilot aim for an aircraft carrier?

texts:
This answer suggests the FPV is aimed ahead of the ship. But it doesn't make sense.

(Picture from linked answer.)

A runway running away at 25 knots, is the same as a stationary runway plus 25 knots headwind.

The relative ground speed is the same, i.e., the rate of closure, and the glide-slope is consistent. Shouldn't the FPV be targeted at the touchdown zone?

Perhaps a bit to starboard, toward the island bridge, because that runway is crabbed. What am I missing?


texts: I'm looking for APU fuel pump location for A320 aircraft series. I'll be much appreciated if you provide a link to some images, schemes.


texts:
Two questions regarding ferry flights:

When an aircraft has to be delivered, who flies it to the destination airport? Does the manufacturer have a dedicated crew for this or is it up to the airline to send someone over?
When an aircraft is sent to Victorville (Southern California Logistics Airport), who flies the plane? Is it a dedicated airline crew or is it a contracted-out service?

Thanks!


texts: Would it have been feasible to install 'conformal fuel tanks' on the Mercure?

texts:
The Dassault Mercure was a short-range twin-jet airliner. It was canceled with sales not reaching the breakeven point. Other similar jetliners like the Boeing 737 had a more convenient longer range.

The structural design features of the Mercure precluded increasing the fuel capacity, but there are jet fighters where conformal fuel tanks were added, same as in the Hypersonic experimental X-15.

Are this type of added fuel tanks a feasible option for increasing the Mercure range?


texts: Who is responsible to check for radar-altimeter disagreement?

texts:
I have searched the site but failed to find a similar question. I know that modern civil aircraft are equipped with multiple radar altimeters. Question is: In the unlikely event of those outputting different values, whose responsibility is it to determine that the values are different? Is it the pilots, or the aircraft is required to warn? Does it depend on the aircraft type?

The question is mostly concerned about this accident: https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_1951


texts: How is a Flying-V more efficient than current fuselage-over-wing designs?

texts:
It's claimed the plane will use 20% less fuel than the Airbus A350-900 while carrying a similar number of passengers -- the Flying-V will seat 314, while the Airbus A350 seats between 300 and 350. The design also mirrors the A350's 65-meter (213 feet) wingspan, enabling it to use existing airport infrastructure.

Source: CNN

All the efficiencies in recent years have come from better & better engines, huge high-bypass turbofans.  This fuselage looks like it'd be a lot draggier than existing fuselage/wing structures since there is so much more frontal area.

If you have a window seat, that window cover better be open if I'm in that row!


texts: What types of non-permanent GoPro mounts exist for the ceiling of a Cessna 172?

texts: What alternatives are available to using a permanent mount to place a GoPro on the inside ceiling center of a Cessna 172?


texts: Do Flight Simulation Instructors stop the simulator before a simulated crash?

texts:
There has been quite a lot of debate in healthcare simulation communities around whether or not to allow a simulated patient to die during training because it might negatively impact the intended training outcomes.
Do flight simulation instructors similarly stop the simulator before the simulated plane crash to avoid the student being negatively impacted (traumatized)? Is this common practice?


texts: The captain of an aircraft flying an international flight is required to have a Restricted Radiotelephone Operator Permit. How do you get one?

texts:
47 CFR 87.87 requires the captain of a US registered aircraft to have their Restricted Radiotelephone Operator Permit (RP) unless it is a domestic flight.

How do you go about getting one?  I used the FCC's website a long time ago and remember that it is terribly confusing.  A great answer would include step-by-step directions for those that haven't had to do it yet!


texts: Why do naval jet aircraft need to have strengthened undercarriages?

texts:
I've read several times that the navy versions of jet aircraft need to have a strengthened undercarriage. Here is one example, and another.

I've always just automatically assumed this was needed because aircraft landings are "rough". That is, the aircraft smacks down hard on the carrier deck (or so went my assumption).

Now I find myself questioning this. Naval jets land by catching a wire that brakes them hard. They may also takeoff with a catapult, which is some running device that pulls the nose gear forward at high g's.

So, what is the real reason that naval versions of jets need a strengthened undercarriage?


texts: Why are the 737's rear doors unusable in a water landing?

texts:
The 737's rear exit doors cannot be used to evacuate the aircraft in the event of a water landing, as shown, for example, in this safety card:

(Image from flight-report, via Jordy here at AvSE.)

In contrast, the rear doors on (for instance) the A320 series can be used for a water evacuation:

(Image by Czechnology here at AvSE.)

Why can't the 737's rear doors be used during a water landing?


texts: How does aircraft design affect carburetor ice?

texts:
The Cessna 172 and Piper Warrior are similar in many ways, including their engines: for most of their production history (1968-1998 for the 172; the entire history for the Warrior) both were equipped with a Lycoming O-320 engine of 150 or 160 horsepower.

One significant difference between the two is in their before-landing checklists: the 172 instructs the pilot to turn carburetor heat on before closing the throttle (p. 4-19):

  Carburetor heat should be applied prior to any significant reduction or closing of the throttle.

Conversely, the Warrior recommends carburetor heat "if required", and even recommends against it unless necessary (p. 4-23):

  Carburetor heat should not be applied unless there is an indication of carburetor icing, since the use of carburetor heat causes a reduction in power which may be critical in case of a go-around. Full throttle operation with carburetor heat on can cause detonation.

Considering that these two aircraft have very similar engines, what would explain such a drastically different approach to the potential danger of carburetor icing?


texts: Do aircraft use the same or similar warning alarms for different alarm conditions?

texts:
I was going through Helios crash and learned that Boeing was blamed for having similar sounding alarms for different alarm conditions.

On a given aircraft, can two different warning alarms have the same sound?
If so, what other aircraft have the same sound for different kinds of alarms?
Has Boeing changed their alarm systems post that incident?


texts: Can you get sucked out of a hole in an aircraft?

texts:
I had always been under the impression that the forces of air rushing out a broken window or hole in an airplane would be pretty limited and nothing near the levels necessary to carry a body through to the outside. The scene in Goldfinger has always been scoffed at by other pilots I have known.

However, recently I discovered that allegedly the pilot of an airliner was sucked out of a cockpit window in 1990 (re-enactment photo below):

Seems fishy to me. Is this for real? Can you really be sucked out of an aircraft window? Remind me to buckle up. Gives a whole new meaning to the word "deplaning".


texts: What procedures are used for midair refueling without air supremacy?

texts:
One of the major themes of the answers to (and comments on) my earlier question about tankers not having ejection seats is that tankers are used only in environments where the threat from enemy aircraft is minimal or nonexistent; for instance:

...Tankers are big, slow, and devoid of defensive measures because they don't need any of that. They're used from a very safe distance, and if there is a risk of enemy air power, friendly air power runs interference...
...Primarily because tankers and transports are being operated in non-combat environments or safely benhind [sic] the front lines of a battlefield so ejection seats are not absolutely necessary for crew survival...
...In the end, it's unlikely a refueler will be shot down. Refuelers are generally only flown in areas where we have control of the airspace, or reason to believe that we are well away from enemy fire...
...A refueler will never be out on it's own. Like I said, they expect aerial supremacy, and have fighters run interference for them. If a fighter is closing on a refueler, full of tens of thousands of pounds of jet fuel, they're already gone...
...For the United States, the assumption is that we will always be able to have air superiority in some area due to overwhelming firepower and technology (though area that may be further away from the battlefield, making the tanker less effective, though still more efficient than landing.) The tanker would never fly directly over the combat zone unless we had air superiority there, as it's quite simply a sitting duck - they have basic defenses though, as you can never guarantee air superiority...
...Tankers are not supposed to be flying in any area where they would be taking enemy fire, so an evacuation situation would essentially be a freak event. Most of the scenarios where a tanker would be attacked have a low survivability anyway...

However, it is quite conceivable that combat aircraft might require mid-air refueling in a situation where air supremacy – or, worse, even air superiority - cannot necessarily be attained (for instance, in a full-scale war between the United States et al and China, or, less likely, Russia), and where restricting tanker aircraft to uncontested airspace would put them so far away from the target(s) being attacked as to be useless.
What are the procedures that are followed for refueling combat aircraft in an environment of mere air superiority or (worse) air parity, rather than air supremacy?  Are the types of tankers used restricted to only those converted from bombers (and thus already possessing both ejection seats and greater maneuverability compared to tankers based off of civilian designs)?  Do aircraft rely solely on buddy tanking (thus tying up most of one’s combat force with tanker duty)?  Are tankers escorted by dense enough swarms of fighters to be able to bull their way through any airspace, no matter how hostile (thus using up most of the tanker’s fuel merely to sustain its own escorts)?  Or do the ministries of war of the countries involved simply resign themselves to having to mass-mail “we regret to inform you” letters?


texts: What are typical insurance premium reductions for renters and owners as they earn instrument and commercial tickets?

texts:
I hear general claims that insurance companies dislike VFR-only pilots and that premiums fall as airmen move up in hours, ratings, and certificate levels.

What are the hard data from the actuarial tables? How do the profiles compare for owners versus renters?


texts: Which 'pusher' propeller aircraft have been used in active military service?

texts:
The only 'pusher' aircraft I know of that has been used in active military service is the SAAB 21. There are several prototypes out there, but I can't see that any others were used.

Which, if any, other aircraft are there? Maybe the Japanese 'shinden' but if memory serves me that is only a prototype.


texts:
Roskam (book: Airplane Aerodynamics and Performance, Subparagraph: 2.5.2 HIGH-SPEED AIRSPEED INDICATORS (COMPRESSIBLE FLOW)) affirms:

  [...] Airplane with no sweep and thick airfoils become transonic at much lower flight Mach numbers than airplanes with significant sweep and thin airfoils. [...]

Question: How does airfoil thickness affect the Mach number at which it experiences transonic flow?


texts: Is it possible for an airliner to cruise at engine full thrust?

texts: What would happen if the pilot of a modern airliner like the boeing 747-800 or Airbus A380 left the throttle at full thrust at cruise altitude for an extended period of time e.g 4 hours if the aircraft had enough fuel to reach the next destination?


texts: How are the structural failures reported to pilot

texts:
For instance an engine separated from aircraft (though most unlikely 1E-13 probability)  or wing got damaged, how is it reported to the pilot?

Will it be reported as 'Engine Fail' or 'Left Wing Fail'?
If so, how is pilot supposed to know if it is a functional failure or a structural failure?


texts: Did/do any commercial passenger aircraft have showers for passenger's use?

texts:
The Emirates A380 has a shower unit for use by First class passengers (previously discussed here), but it got me thinking about the many passenger comforts present in the "golden age" of aviation (pre-US airline industry deregulation, especially when piano lounges were a thing in 747 aircraft) - did any other commercial passenger aircraft (jets or otherwise) have onboard showers for the benefit of passengers?

If not, it seems surprising, because a toilet room could easily be converted to a wet-room shower unit - and aircraft have a ready supply of potable water. Showers could be time-limited to a few minutes - enough to freshen-up after a long-haul flight and I can see it would be popular with business travelers who might not have the luxury of time to use their airlines' business class lounge's showers.


texts: Barometric altimeter data during high vertical g-forces?

texts:
I’m contemplating that that under high vertical acceleration (such as the maximum limit of 2.5g for commercial airplanes), that hydrostatic atmospheric pressure wouldn’t be a complete model. Wikipedia states for atmospheric pressure:

  In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point.

The derivation of the Barometric formula presumes hydrostatic pressure:

  And assuming that all pressure is hydrostatic:

    dP=-ρgdz

It appears to me that without correction for the g-forces, a vertically accelerating barometric altimeter could potentially indicate uncorrected altitudes which are lower or higher (depending on the design of the altimeter) than true altitude even if all other factors had been corrected.

Is this a correct understanding and do Air Data Computers (ADC) described below make these corrections? If yes, can anyone provide an approximate formula or mathematical model for altitudes near ground level?

Another Aviation Stackexchange answer states:

  However, altitude is also used for the purpose of traffic separation, and for this purpose, neither QNH or QNE is corrected. This might sound counter-intuitive, but as long as your altimeter is showing the same error as any conflicting traffic, you can be safely separated, therefore: The altitude shown on the altimeter is not corrected at all (except by calibration for possible aerodynamic interference, such as compressibility, venturi-effects etc).

  In technically sophisticated aircraft, barometric altitude input is used for vertical navigation. Since vertical navigation is concerned with the true altitude of the aircraft, the aircrafts Air Data Computer (ADC) will calculated a true altitude based on information available to it (either through sensors, or through pilot input). The true altitude is however, as stated, not shown on the pilots primary flight instruments.


texts: What frequency should be used for air-to-ground communication other than airport ground operation?

texts:
On a VFR flight, what frequency should be used to talk to somebody on the ground in USA?

In another word, if I am overflying my house and I would like to talk to the people on the ground, what frequency should I be using? Is it even legal to do something like this?


texts: Are DPEs incentivized to fail people on checkrides so they can collect extra money on re-tests?

texts:
I'm almost ready for my private pilot checkride, and it seems to me there is a perverse incentive for DPEs in passing or failing people.

If a DPE makes additional money on re-checks for students who fail the checkride, then it seems to me that DPEs have have a strong financial incentive to fail people the first time so that they can collect additional fees on the re-test. In fact, it seems that there are no rules in place to stop a DPE from making a student do the checkride 4, 5, or 6 times and collecting additional money from the student every time.

The checkride fee is exorbitant ($900 here in Southern California), but I'm even more concerned that the DPE would be hoping to fail me so they could collect extra money from me on a re-check. It actually makes my blood boil just thinking about it.

I'm not saying that DPEs are bad people, but the incentive structure certainly seems to make it easy for them to exploit eager students, and if economics has taught us anything, it has taught us that people respond to incentives.


texts: Would TCAS ever issue a "climb, climb!" RA that would stall a jet with a low airspeed?

texts:
As a for instance, let's say there are 2 jets going at low airspeeds (close to $V_S$) that get too close to eachother and a TCAS Resolution Advisory callout is announced.

Would TCAS issue an RA to order one of the jets to climb, resulting in loss of airspeed and a stall?


texts: Propeller Curve Modification on Test Rig

texts:
this is my first stack exchange question so please bear with me if I have missed a rule: I tried searching for this question to no avail.

I have an off-the-shelf propeller for the purpose of eventual high-altitude flying. I used the airfoil profiles to make an approximate propeller efficiency/c_thrust/c_torque/c_power vs advance ratio curves, as well as the power/thrust/torque/rpm vs airspeed.

My question is: if I had to spin up this prop on a test rig on the ground, there are two major changes I can see - atmospheric air density, and the fact that airspeed is zero. How can I predict how the propeller will behave when the airspeed is held zero (the rig will cancel out the thrust generated). Looking for things like max possible RPM, torque, etc. and how the behavior of the propeller changes.

Thanks a lot, happy to provide more details.


texts: I spotted this recently. The distance and poor camera makes it really hard to determine what it is. Any help appreciated. Thanks.


texts: How can I take 360° panoramic pictures in an aircraft or helicopter?

texts:
I would like to receive some answer or advice on how to create 360 panorama images.
My plan is to use Cessna or Helicopter.


texts: Who pilots an aircraft that is on a delivery flight?

texts:
Right about now (Jan 28, 2016, 08:12 UTC), a Boeing 737-8AS is cruising over Manitoba/Nunavut on a delivery flight from Seattle Boeing Field (BFI) to Dublin Airport (DUB). The flight is labelled RYR800F, and is clearly a delivery flight for the European low-cost airline Ryanair.

I have always wondered who flies the plane in such situations. I would appreciate if you could give me a few insights into how these events are managed by the manufacturer and the Company. I envision the following cases, but which one of them, or combination of them, is true?

1) The plane is flown by a special pilot unit of the buying Company, which flies to the manufacturer's logistic airport, checks for conformity, signs a few documents, and then flies the plane to the Company's headquarters or hub;

2) The plane is flown by a special pilot unit of the manufacturer. They fly the plane to the Company's headquarters or hub, then meet the buyer to check for conformity and sign the documents. Eventually, the pilot unit flies back to manufacturer's base as regular passengers onboard other flights;

3) The plane is flown by two units: one belongs to the manufacturer and the other to the buyer. They check for conformity, sign the documents, and jointly fly the plane, in order for the manufacturer and the buyer to share immediate feedback on the plane's performance while airborne;

4) The plane is flown by a contracted pilot unit, which performs the duty as a third party payed by the buyer or by both the buyer and the manufacturer. This unit also includes a member of the buyer. They reach the manufacturer's base, the buyer's employee signs the documents, and then the plane is flown to the Company's headquarters or hub.

I assume each Company has its own policy in this regard, but which one of these procedures do you think is the most common? Thanks!


texts: American Airlines Astrojet - is it really 'polished aluminium'?

texts:
I came upon this article, referring to American Airlines' roll-out of a 737-800 in their Astrojet livery. In the article it describes this as 'polished aluminium'.

(Photo supplied by American Airlines)

This got me to wondering:

Is this actually polished aluminium, or has some sort of clear lacquer been applied?

If it is polished aluminium,

What is the impact of exposing the airframe to the elements, rather than protecting it with a layer of paint?
What benefits might accrue from this in weight-saving, fuel burn, etc.?


texts: Are there regulations or adverse effects regarding Bluetooth in the cockpit?

texts: Are there any FAA regulations concerning wireless Bluetooth headsets in the cockpit of any aircraft? Moreover, I'm interested in finding out if the Bluetooth protocol (IEEE 802.15.1) will adversely affect any aircraft avionics in terms of radio interference or other Electromagnetic Interference (EMI). If anyone has any experience with this, thoughts and comments would be greatly appreciated.


texts: Does the yoke move when trimming a THS like it does when using elevator trim?

texts:
I would like a clarification from the operational point of view:
Both the THS and elevator trim tab is used to remove pilot pressure on the yoke / stick.
On the elevator trim similar to the C-172 the yoke deflection is a function of the speed: so in trimmed condition the yoke deflection depends on the IAS we what to fly.
What happens on the THS trimming? Does the yoke deflection always stays in a "center" position after trimming or the behavior is similar to the C-172 ?


texts: Why does An-225 (Mriya) perform a low-pass on its landings?

texts:
Today was a big event for aviation fans where I live (Warsaw, Poland, EPWA). We have had a visit of Antonov 225 (Mriya).

Today, but also as I saw in other videos, it often (always?) performs a low-pass first and only then lands. Why is that? I bet this is about safety, but...

is it mandated by some official rules?
or by some internal rules of the operating airline?

What kind of information does the pilot need which they wouldn't get by reading the maps, diagrams or by talking to ATC?


texts: How serious is the problem of "stopping too far" next to the jet bridge?

texts:
In the answer to the recent question "How does an airliner adjust ...", there is the mentioning of the signal: "STOP TOO FAR". But what to do if you see this?
In other words, if the airliner stops too far next to the jet bridge, how is this problem typically resolved? I was thinking about the possible approaches:

In my car, I would just drive backwards. But seems that the usage of the reverse thrust is somewhat frowned upon.
The aircraft will be serviced without the jet bridge (movable stairs, etc).
The aircraft will be towed backwards where it should be.
The jet way most often can be adjusted to compensate the unexpected location, the sign is just the warning.
No ATPL holder would ever make a mistake of this kind anyway.

Also, how often does this happen? Is this a very rare problem or something more common?


texts: What does "Crew: Top of your mind!" mean in commercial aircrafts?

texts:
On a flight this year in Europe, the pilot or co-pilot announced midflight "Crew: Top of your mind!" via the loudspeakers. The crew didn't visible react on that and I couldn't notify any change in the flight after that. What does this announcement mean?

The flight was either with Swiss, Air Serbia, SAS or IcelandAir. Unfortunately, I can't remember which one.


texts: Would it be possible to use 3D printed node based structures to make cheaper GA planes?

texts: A car boasting 700HP and under the U.S LSA weight limit was just announced by Divergent Technologies. I was curious on peoples thoughts on using this technique in planes. Obviously there are some issues with the surface of the structure bearing load, but I imagine these could be overcome.


texts: Why was this helicopter denied entry to Class B airspace?

texts:
This question is somewhat related to this other one.

I listened to this exchange between a helicopter and Newark.

The helicopter wants to land at Newark. The controller tells the helicopter to remain clear of the Class B. I'm aware that the controllers must give clearance to operate in certain classes of airspace, and the helicopter wasn't granted clearance to do so.

Why was the helicopter denied (as far as can be deduced)?

What should the pilot have done differently, either to get clearance to land at Newark or to anticipate not being able to?


texts: What is the function of these “tubes” that cover the outboard exhaust stacks on some PBY-5A and PBY-6A aircraft?


texts: If ATC doesn't assign an obstacle departure procedure in an IFR clearance, what should you do?

texts:
If ATC doesn't assign an obstacle departure procedure (ODP) as part of an IFR clearance can you use one anyway?
And if there is no ODP, do you then follow the 35ft at runway threshold / 400ft at first turn / 200ft/nm rule, then turn on course on your own?


texts: What does the phrase "electrically controlled and pneumatically operated" mean?

texts: While studying the air-conditioning of the A320 from the FCOM I came across the information that the pack flow valves are "electrically controlled and pneumatically operated". I can not understand what it means.


texts: How does the MD 900 accomplish auto rotation with the NOTAR system?

texts:
The MD-900 is a helicopter which seems to be quite popular with law enforcement agencies.

As you can see, instead of an anti-torque tail rotor, a fan exhaust is directed out slots in the tail boom. I was wondering if this works in regards to auto rotation, should the aircraft lose its engines.


texts: Does a "take-off" assist make sense for electric aircraft?

texts:
There is already a good answer that talks about how a catapult provides virtually no benefit for fuel-based aircraft.

However, I'm wondering if the same answer is true for electric planes?  For example, I see here:

  The high-lift [leading edge] propellers are all used during takeoff….
  Once you get to a comfortable margin, say 30 percent above stall
  speed, then it will just run off the cruise [wingtip] props and you
  can fold the [blades on the] lift propellers.

This suggests to me that the aerodynamics, complexity, and weight of (at least that design of) electric aircraft could be improved if there were some other means of getting planes up to speed.

While a catapult is a pleasingly high tech solution, there are a number of reasons (some mentioned in that other answer) that make it impractical.

But what about some lower-tech options?  A truck with a tow rope?  A specially designed cart that the plane sits in that accelerates it up to take off velocity?

I know, that's not going to be practical for jumbo-jet sized craft.  But for planes that seat (say) a dozen passengers, could this be a part of the solution?  Or does the math work out essentially the same?

EDIT in response to GdD's question What problem are you trying to solve?

The biggest obstacles to adopting electric aircraft are the limitations imposed by today's battery technology.  My question is intended to determine whether take off assist could address that limitation both by alleviating the high demand for power at take off, and by reducing the weight, complexity, etc of equipment that is only needed at take off.

So, the first part of the question is: Would any type of "take off assist" make useful contributions to the operation of electric airplanes?

Peter Kämpf's answer is "no" for existing aircraft.  But does electric make things different?  Especially given that electric airplanes are currently being designed from scratch?

The second part of the question is: Would any useful "take off assist" for electric planes be viable?

While a steam-powered, extended-length catapult might be both possible and beneficial (and cool), it's hard to believe it's ever going to be practical.  But if a truck with a tow rope allows you to extend the plane's range by 25% while also reducing cost and maintenance, that seems interesting.

To address jamesqf's other comment, my target family of aircraft is something along the lines of Eviation's Alice.

I guess I'm just wondering if electric airplane designers are failing to consider it just because that's how existing planes work?  Or have they done the math?


texts: Why must the long cross-country flight for a commercial rating be solo?

texts:
Assuming I am interpreting the below FAR correctly, one must either be solo, or have an instructor present to complete the long cross country requirement. More specifically, it seems to me that you could meet the requirements with a passenger present if an instructor is on board.

§61.129   Aeronautical experience.
(4) Ten hours of solo flight time in a single engine airplane or 10 hours of flight time performing the duties of pilot in command in a single engine airplane with an authorized instructor on board (either of which may be credited towards the flight time requirement under paragraph (a)(2) of this section), on the areas of operation listed under §61.127(b)(1) that include—
(i) One cross-country flight of not less than 300 nautical miles total distance, with landings at a minimum of three points, one of which is a straight-line distance of at least 250 nautical miles from the original departure point.

I'm trying to understand what the purpose of the solo requirement is, and how it could be alternatively achieved without being solo, but only if an instructor is onboard.
It's clearly not for safety of the passenger, since, as a private pilot, its completely legal for me to make the very same flight with a passenger; I just can't use it to meet the commercial requirement quoted above. Why not? And how could adding an instructor to the plane make any difference?


texts: What security regulations apply to US private airstrips?

texts:
What kind of security regulations govern the 15,000 private airstrips in the U.S.?  Do they fall under TSA jurisdiction?

I'm a freelance writer working on a story and wondering how senior Al Qaeda operative, Adnan Shukrijumah, was able to fly unhindered from Mexico to Cielo Dorado in Anthony, New Mexico.

Is this kind of laxity uncommon or par for the course at all private airstrips?


texts: Why does the EGT gauge in 172s have no numbers on it?

texts: So the EGT gauge on the 172 (and other cessna singles?) doesn't have a numerical scale on it, just markings every 25 degrees.  I know that one is supposed to use the EGT for leaning operations (ROP, LOP, what have you), but it's always stymied me that there are no actual numbers on it.  Any reason why this is so?


texts:
This Popular Mechanics article writes (about the B-2 Spirit).

  Only 543 people have ever flown in the cockpit of a B-2. Upon landing I'll become number 544, with the new Air Force handle "Spirit 544."

Do people who have flown in B-2 Spirits have the Air Force handle "Spirit ###?"
If so, which regulation/directive/etc. specifies that the handle of people who have ever flown in the cockpit of a B-2 Spirit be "Spirit ###?"


texts: What is the procedure for restarting an F-16 in the air?

texts:
If there is a flameout on the F-16 in the air, what is the procedure for restarting it?

I'm sure this is an elaborate checklist, so I'm only asking for an overview of the key parts, especially I'm interested in to what extent the pilot has to manually operate this process.

Is it required to manipulate fuel? Ignition? Temp? Air source? Does it involve the JFS system? Battery?

This https://www.quora.com/How-do-you-start-the-engine-on-an-F-16-Fighting-Falcon provides a nice little overview of how to start an F-16, with some pictures. However, it doesn't explain exactly how the engine is ignited in the first place. JFS, then engage throttle to allow fuel in, and magically it ignites? Surely it doesn't ignite just from pressure alone when driven by the JFS? It feels like a crucial step is missing in that overview and that step would probably allude to how to restart the engine.

It seems that in the event of a flameout, on at least block 50 F-16's Can fighter aircraft glide? the EPU (Emergency Power Unit) kicks in which provides power and hydraulics. Prior to this, the battery supplies power (but I imagine it must be turned on manually, as there is a switch for this!) and the hydraulics appear to work for some time even without the EPU, JFS or the main engine.

However, I know nothing about how the engine actually gets restarted. What does the pilot need to do, and why?

As a bonus question: Why doesn't this guy attempt to restart the engine? Did they already try, and give up?


texts: Raising flaps on touchdown in gusty conditions

texts:
In As the Pro Flies, John R. Hoyt writes (pages 41-42):

  Suppose we have to land in high, gusty winds. That's what happened to
  Pilot Z, who once landed his plane during such conditions with his
  flaps down. After the wheels were on the runway he relaxed, never
  realizing that a plane is not landed until the switches are cut.
  Because he still had airspeed and because full flaps lowered the
  take-off speed, a small gust of wind was all that he needed to begin
  flying again. The additional lift was enough to raise him 10 feet from
  the runway, and at that point he ran out of gust, a condition aptly
  described as dis-gusted. He would have dropped back on the runway, had
  not an alert co-pilot opened the throttles and saved both the day and
  the landing gear.

He goes on to state how much flap should be used in what conditions, and then he finishes with this:

  Let us then raise the flaps in gusty or crosswinds as soon as the
  wheels touch down. To wait until it is time to taxi doesn't help slow
  the plane very much, and flaps do constitute a hazard in gusts.
  Besides, it is surprising how much a small pebble costs when it goes
  through a flap.

Is he right? Should flaps be raised immediately after touchdown in gusty conditions?


texts: Fuel dumping seems to have a lot of restrictions, like the need to do it above a certain altitude and over water. It also has to end up somewhere, even if it vaporizes, which is less than desirable. It seems like burning off fuel as it's dumped could solve these problems. Obviously there's the risk of rapid unplanned incineration, but what are the other factors?


texts: How do paper airplanes create lift if their wings are flat?

texts: Paper airplanes' wings are completely flat, unlike the droplet shaped curvature of a full sized wing. How does a flat wing generate any lift if both sides have the same air pressure?


texts: Need help identifying civilian small aircraft from old turkish movie

texts:
I need help identifying a plane from an older 1977 turkish comedy movie for a personal project, these are the best (and only) shots it can be seen.
Flyby
Front Angle
Close up cockpit outside


texts: What are the details of opening a cockpit door from the outside?

texts:
Can one pilot lock the other out of the cockpit?

It is mentioned in the answer to the question I linked that a person inside the cockpit can stop a person outside from opening the door by "canceling the unlock process". This leads to several further questions:

How exactly does the person on the inside "cancel the unlock process" (Press a button, flip a switch, enter "counter code", etc...)
It seems there is a delay before the door opens. Is this correct? What's the duration of the delay?
What are the "authority levels" of codes? Which levels exist, what do they mean?
What is the confidentiality policy regarding those codes in theory and practice? (Who gets what authority level code officially? If stewards/stewardesses are not allowed to have the codes do pilots usually pass them on anyways?)


texts: How does experienced pressure vary with airspeed?

texts:
Drag increases with the square of airspeed. Is the same true of the pressure that a forward-facing area experiences?

As an aircraft approaches and then exceeds the speed of sound, how does experienced pressure on a forward-facing area increase?


texts: Is it really required for a pilot to have good eye sight?

texts:
My basic knowledge says that it is not necessary for a pilot to have good eye sight,  he can use spectacles.

In an article I came to know that :
The United Kingdom Civil Aviation Authority state the following:

‘An applicant may be assessed as fit with hypermetropia not exceeding +5.0 dioptres, myopia not exceeding -6.0 dioptres, astigmatism not exceeding 2.0 dioptres, and anisometropia not exceeding 2.0 dioptres, provided that optimal correction has been considered and no significant pathology is demonstrated. Monocular visual acuities should be 6/6 or better.’

*Above eye problems are high level of eye defect.

• We should be worried on normal eye problem a serious problem to become a pilot ?


texts: How can seagulls slide in the wind without flapping their wings?

texts:
There are a lot of seagulls in a park near where I live. Sometimes I can see them somehow "sliding" forward or backward diagonally when flying against the wind, however, their wings aren't flapping. What are the flight mechanics behind this?

Can gliders mimic this style of flight?


texts: Why do few small planes have reflexed flaps?

texts:
Reflex flaps capability is very common in flapped gliders, but outside of gliders I am only aware of the Maule which has this feature. https://aviation.stackexchange.com/a/37753/20394 shows the advantage gliders gain from reflex position, so presumably this would hold for more aircraft than just gliders.

I can see how with certain types of flaps, such as fowlers, the mechanism would be impossibly complex. But for other types with a simple pivot this must be more attainable.


texts: Is a retreating blade stall a problem that can be overcome on dual-rotor helicopters?

texts:
I know that regular main+tail rotor helicopters stall at higher speeds as the relative airspeed of the retreating blade approaches zero.

I'm curious if coaxial or intermeshing dual-rotor helicopters are affected by the same or a similar problem.

I'm aware that other factors may dominate and impose speed limits on them as well, but I'd like to know if a retreating blade stall is a problem that can be overcome with dual rotors.


texts: What makes V1 one or two knots less than Vr on this performance table?

texts:
(B738 AFM, 0-2000 feet elevation, up to 27°C) Example of V1 and Vr differences.

The table shows that the V1 speeds are invariably one or two knots lower than their matching Vr speeds. Given that V1 can equal Vr, what's the limiting factor (probably factors) that puts V1 one or two knots below Vr? Vmbe might be one, but is it the only possible limiting factor here?

Or perhaps the V1 speeds are the same with the matching Vmcg speeds because that's operationally more advantageous in some ways than V1s being the same as the higher Vr speeds?

Or are the V1 speeds the speeds that bring the balanced field lengths, which require the mimimum runway distance?


texts: where can i get a aviation map of korea with the moes, and highways and vectors

texts: ive been searching for a aviation map of South Korea and cant find anyone that sells it. does anyone know where I can find one for flight planning


texts: I know that alpha induced rise with increasing AoA but how much is alpha induced in reality ,are we talking about 1-2 degrees or more?


texts: In modern two-engine planes, if one pilot is disabled, it's my understanding that the remaining pilot can safely fly and land the plane. But what about in aircraft like the 727, which had two pilots and a flight engineer? Assuming the FE had flight training, could they land the plane if the two pilots up front were incapacitated? More generally, what is the minimum number of pilots required to safely land a jet with a three-person cockpit?


texts: What is this c. 1930 beautiful monoplane seen in Oakland?

texts:
Photo from Denny Wright's album.  He piloted for
Clyde Sunderland.  This photo has no stamp or markings. Anyone recognize this aircraft?


texts: What is a jet (unit) shown in Windows 10 calculator?

texts:
From Windows 10's calculator:

What is a "jet" (physical unit)?

And why does it equal 480 knots or 888,88 km/h, if a jetliner's cruising speed is around 950 km/s? Or why does it equal 0.73 M, if a regular jetliner's cruising speed is 0.85 M?


texts: What are the reasons for not wearing polarized glasses during flying, if glass cockpit and polarized windshield aren't an issue?

texts:
So far the only reasons I can find are the newer planes come with polarized windshields that goes dark when you wear polarized glasses and the fact that glass cockpits become dark.

But is there a single reason to not wear polarized glasses while flying something like an vintage J3 Cub with nothing but some gauges etc? Can you see the PAPI lights and other necessary stuff? What keeps an pilot from wearing polarized glasses?


texts: Why are Oscar, India, and X-Ray (O, I, and X) not used as taxiway identifiers?

texts:
An old CAR "Licensing of Aerodromes" document indicated that taxiways may not be designated by O, I, or X.

Is this still in effect today?  Why were (or are) those not used as taxiway identifiers?

My guess is that the shapes of those letters could cause confusion such as an "X" meaning something like "closed" or I looking like a vertical line "|".


texts: Could turbine or compressor stages of a jet engine be switched off to improve fuel efficiency?

texts: Active fuel management is a technology developed by General Motors, which is used to improve engine efficiency in the times when the engine is operating under loads which are considerably less than the rated load, as shown in this link. This technology exploits the property of piston engines where some of the cylinders are turned OFF while only few of them work, and hence improving the overall efficiency of the engine. Can a similar technique be employed on an aircraft's engines, where some of the turbine stages (Compressor or Turbine) are switched off in order to improve the performance efficiency of the engine?


texts: Are larger aircraft inherently better-suited to long-distance flights?

texts: Restricting this to larger passenger aircraft, and apart from the greater range made possible by larger fuel tanks, are larger aircraft better-suited to long-distance flights simply in virtue of their size?


texts: Do commercial airliners use supercritical airfoils?

texts:
I was looking how speed is distributed on this B747 airfoil:

Source.

Nearly all of the upper surface has air flowing above Mach 1. I'm wondering if this is frequent for commercial airliners to use supercritical airfoils? I'm particularly interested in the A330 case.


texts:
This puzzles me a bit, and I cannot find the answer anywhere.
Does bi-wings create essentially double the uplift as single wings?


texts:
As we know, at higher altitudes the dose of UV rays increases, and planes usually spend a larger time there, then why aren't windows of airplanes made UV proof. A simple coating on the inside might solve the problem.

Relevant question


texts: Can planes fly without wings but with a horizontal stabiliser?

texts: There are X-Wings in Star Wars and I have been making a model recently. So can planes fly without wings but with a horizontal stabiliser?


texts: Can cruise pilots/second officers go for years without doing a takeoff or landing?

texts: I was looking at the description of this role i.e. someone who provides cruise flight relief flying. As conceivably, someone could be bonded for multiple years because of the type rating being covered by the airline, it is possible they could 'fly' for multiple years and yet never actually do a real takeoff or landing?


texts: Myth or Fact? U.K pilots struggling for work while U.S big airlines are kicking down the door for pilots with an American passport

texts:
Myth or Fact? Why are U.K/British pilots struggling to find their first job, then once they get the hours are still struggling? The question Is... Is it easier to get a job being a American Aviator Or British Aviator. For Aviation

There are even TV Shows about pilots having to travel across the world just to find work with a British passport. Worst Place To Be A Pilot - Season 1 / Episode 3 - Full Episode

Meanwhile, CNN posted an article that U.S American pilots are in heavy demand and big companies are practically kicking down the door for new pilots. I list my sources so you know what I'm talking about.

Is it a fact that U.S student pilots are having trouble paying for training with the U.S economy or is it because there are harsher rules for Americans so now less people are meeting the requirements? Are older pilots retiring? etc.

 I would hyper link but I don't have enough reputation points


texts: How does turbofan engine performance depend on speed and density altutude?

texts:
I am looking at a simulation engine (jsbsim). Their turbine engine simulation requires a function, given by table, of thrust at Mach number and density altitude.

Engine definitions generated by their initial configuration generator and all existing configurations I found use the same function that is based on data for [Rolls-Royce/Snecma Olympus 593]. Since that is a turbojet with supersonic intake duct that increases performance at transsonic and supersonic speeds, I somehow doubt the function is appropriate for high-bypass turbofans with simple pitot inlet.

For reference, the table looks like:

     |  -10000       0   10000   20000   30000   40000   50000
-----+--------------------------------------------------------
0.0  |  1.2600  1.0000  0.7400  0.5340  0.3720  0.2410  0.1490
0.2  |  1.1710  0.9340  0.6970  0.5060  0.3550  0.2310  0.1430
0.4  |  1.1500  0.9210  0.6920  0.5060  0.3570  0.2330  0.1450
0.6  |  1.1810  0.9510  0.7210  0.5320  0.3780  0.2480  0.1540
0.8  |  1.2580  1.0200  0.7820  0.5820  0.4170  0.2750  0.1700
1.0  |  1.3690  1.1200  0.8710  0.6510  0.4750  0.3150  0.1950
1.2  |  1.4850  1.2300  0.9750  0.7440  0.5450  0.3640  0.2250
1.4  |  1.5941  1.3400  1.0860  0.8450  0.6280  0.4240  0.2630

where rows are Mach number, columns are density altitude in feet and the values are fractions of rated thrust at zero speed at sea level.

The thrust decreases with altitude, which is OK. But with Mach number it only decreases initially and at M0.8 it is already more than static thrust. I had the impression that this requires high exhaust speed and therefore isn't, and can't, be true for turbofans with their low exhaust speed.

So I'd like to know whether:

how appropriate or inappropriate those values are for high-bypass turbofans, especially the recent types with bypass ratio up to 11:1 and
where I could get any better data.

I understand the actual data for new engines will be proprietary. I just hope to do better than using data for old and very different engine designed for different operating range.


texts: Why are some ATC call signs different than the flight number?

texts:
When listening to air control traffic, or watching flights on flightradar24.com, some flights show up with ATC call signs (as transmitted on ADS-B) that do not match the flight number as they usually do, some examples:

TK1880 / THY9QT
TOM6347 / TOM1FT
LH1660 / DLH5KK

It seems to be more frequent on flight codes that have 4 digits, but this isn't exclusive. Who assigns these call signs, and what is the pattern for the naming?


texts: Why is the alternate static pressure lower than the standard static vent pressure regardless of the venturi effect on both?

texts:
I understand that the higher relative airspeed around the body of an aircraft in comparison to the air within the cabin causes the cabin to experience a lower pressure.

However, I was just thinking about this concept, and it dawned on me that I have never questioned why this causes a difference in this particular discussion as it relates to standard vs. alternate static ports.

Are the standard static ports on the side of the hull not also experiencing this effect as air passes nearly perpendicular to the standard static port openings as it flows along the body of the aircraft?

Why is the venturi affect stronger around the cabin than it is around the static port holes on the side of the hull at the same indicated airspeed?


texts: Did the Wright brothers patent their Wing Warping method in Germany?

texts:
I know that the Wright brothers patented their Wing Warping method for controlling the roll of a plane or glider in Great Britain, France, United States, Austria, Italy,... but did they obtain a patent for it in Germany?

This is the Austrian patent:

Orville and Wilbur Wright, “Austrian Patent No. 23174 – Flugmaschine”, Filed: 23 March, 1904, Beginning of patent term: 15 September, 1905, Issued: 26 February, 1906, 3 pages.

They have a German patent published in 1906 (see below) but I never found its content. I do not know what is written in it.

Orville Wright und Wilbur Wright in Dayton, (V. St. A.)
Patentschrift. Nr. 173378. Klasse 77h. Gruppe 7. Mitwagerechtem Kopfruder und senkrechtem Schwanzruder versehener Gleitflieger. Patentiert im Deutschen Reichevom 24. M rz 1904 ab. Ausgegeben den 16. Juli 1906. Berlin: Kaiserliches Patentamt, 1906, 4 pp., +illus.


texts: What is this three-bladed vintage aircraft?

texts:
We found this poster at IKEA, EDELVIK Poster 103.776.29.

Allposters.com has another poster, which includes the same aircraft, but 2 in formation, possibly the same original photo/artist?


texts: How can I avoid floating during short-field landings?

texts:
I fly a Piper Cherokee PA-28R for my training and have a question about the techniques used for a short field landing.

What is the difference between a normal landing roundout/flare and a short-field landing roundout/flare? Should I begin the roundout and/or idle the power sooner to get minimum floating? Where does the difference in 'float distance' come from?


texts: Is it possible to re-engine aircraft with different engine options?

texts: Most airliners have multiple engine options and so I was wondering if it would be possible for operators to fit a different engine type to their existing aircraft; let's take for instance the Boeing 747-400 fitted with RB211-524Gs. Could these be interchanged with PW4000s or GE CF6s or would the differing wing loadings require structural changes to be made?


texts: When a hold is distance based, do you still used a timed entry?

texts: Let's say you have to do a parallel or tear-drop entry to enter this distance-based holding pattern.  Do you still fly outbound from the fix for one minute and then make your turn inbound to re-intercept the fix or are you taking it to 4 NM?


texts: Is there an aviation career where I would help design an entire aircraft and its systems?

texts:
If I want to design and build planes, what career would that be? Would it be a mechanical engineer, systems engineer, or what else. (I feel like saying aerospace engineer is too vague and most companies like Lockheed Martin don't have that as a job but mostly as a business unit other jobs fall under.)
Also, is there a job in which you design and build planes and pilot planes? I really want to become an engineer that designs planes but still want to pilot them as a fighter pilot or test pilot, I just want to know if there is possibility of doing both.


texts:
Can tilt-rotors like the V-22 execute an autorotation landing?

If so, are the conditions under which that would be possible (and survivable) different from a helicopter?


texts: Where is the mistake in this air density calculation?

texts:
I intend to compute the air density, $\rho$ at an altitude of $h=15000ft=4572m$, with an ISA deviation of $\Delta_{ISA}=18^{\circ} F=10\,K$.

Well I first computed the real temperature of the air at $h$ altitude with the following ISA temperature realtions:

$$T_{ISA}[K]=288.15-0.0065\,h[m]=258.432\,K$$
$$T=T_{ISA}+\Delta_{ISA}=268.432\,K$$

I then computed the temperature altitude, i.e. the $ISA$ altitude for a temperature $T$:

$$h_T[m]=\frac{T[K]-288.15}{-0.0065}=3034m$$

With $h_T$ computed I got the air density by the respective ISA relation:

$$\rho[kg/m^3]=1.225\left(1-0.0065\frac{h_T [m]}{288.15}\right)^{4.25588}= 0.906kg/m^3$$

The problem is that this value is different from what I got here ($\rho=0.742 kg/m^3$)

What did I do wrong?


texts: Is there a published airspeed and TPA for Class B approach at San Diego International?

texts: I live in San Diego almost directly underneath the downwind leg of the normal approach (from the north) to Lindbergh Field (KSAN).  The Class B airspace for the entire downwind and base leg areas is between 10,000 and 4,800 feet.  Every night I stand out on my back deck and watch the approaches being flown overhead.  It appears to me that the airspeeds and altitudes of these approaches are very similar and I'm curious about what they are.  Are these published anywhere or is there some accepted norm for a typical airliner approach to a sea level airport?  Although I could be mistaken, as I watch the turns from downwind to base and base to final, it appears that the altitude is held fairly constant and that final descent doesn't start until final approach. If anyone has any insights, I'd be interested to hear what they are.


texts: What is the procedure if both pilots are incapacitated?

texts: Let's say both pilots passed out , is there anyone else from cabin crew that is trained enough to land a plane?


texts: What are these markings on the runway at Haneda Airport?

texts:
I haven't seen these markings in other airports in the world. Look:

They also appear in other Japanese airports. What do they mean?


texts: What wind change gradient is necessary to be classified as wind shear?

texts:
Wind shear is defined as a sudden change in the speed or direction of the wind with altitude.  There's got to be some ratio of speed to altitude or directional change to altitude beyond which it's defined as shear, but I can't figure out what it is.

What is the actual change in wind direction or speed over altitude for a wind shift to become considered wind shear?


texts: Why are rotary wing aircraft less efficient than fixed wing aircraft?

texts:
This question showed that rotary wing is less efficient than fixed wing, but the answers don't really address why.

Why are rotary wing aircraft less efficient than their fixed-wing counterparts?

It seems to me that the most important thing for efficiency is lift-to-drag ratio, so what makes this ratio much worse in rotary wing? Presumably it can use the same airfoil shape as fixed wing aircraft, so I could imagine a similar lift to drag ratio.


texts:
From what I know MAP is a way of measuring engine power with variable pitch propeller. Greater throttle setting - greater power - greater MAP on the gauge. It happens because MAP is in fact vacum pressure so opening the throttle gives greater fuel and air flow into the manifold, explained here:
Why does manifold pressure increase with power?

But I also read somwehere that when we reduce rpm without touching the throttle, the MAP will increase, according to this topic:What happens to manifold pressure reading following a reduction in both throttle and RPM?

Reducing throttle decreases manifold pressure. Reducing rpm reduces suction, so the MAP should then increase?

The question is:  why does reducing rpm increase MAP?


texts: Can I derive the wind speed and direction?

texts:
If I know the IAS and GS (with directional components) of an aircraft, can I derive the wind speed and direction?
I'm working on an application that simulates the flight of an aircraft.  Another application that takes as input, the computed trajectory of my aircraft, which includes the IAS and GS of the aircraft (at points along the trajectory) needs to know the wind speed and direction at those points.
I think it is possible, but am not sure, to isolate the wind speed and direction using the IAS/GS (or both).
Can someone confirm this?  Is this a reliable way to do this?  Do I need other information to complete the calculation?


texts: Why doesn't the Concorde have any wing fences?

texts:
A Wing Fence is a straight, vertical "fence" running from forwards to backwards down the wing.

This MiG-17 has three fences per wing. I've also seen them on delta-winged aircraft such as the MiG-25.

The purpose of the wing fence is to prevent the air from flowing sideways over the wing. Air instead becomes trapped between the fences and flows front to back as normal. This is the ideal condition for creating lift, because the air follows the camber of the wing.

So why doesn't the Concorde have them?

The even more extreme sweep (at first) of Concorde's wing seems to me like it would induce even more sideways-flowing air, meaning it should benefit even more from wing fences.

(I noticed the Tupolev Tu-144 doesn't have them either.)


texts: How are Cd and Cl calculated from Cp data?

texts:
Given pressure coefficient data for corresponding x/c (position along chord) values on a wing, I am looking to calculate coefficients of drag and lift. Here's what I have: b, MAC, S, sweep angles at LE & c/4, and Cp vs. x/c data for 6 different stations (span position given). Angle of attack is 0 degrees.

I understand that to calculate Cl, I can numerically integrate Cp with respect to x/c from 0 to 1. (ignoring skin friction [which, I know, is not best practice])

To calculate Cd (again ignoring skin friction), I believe I need to perform the same integration but with the Cp values being first multiplied by dz/dx inside the integrand, where z corresponds with the airfoil thickness.

My problem is that I do not have any information on the airfoil thickness. Any thoughts on approaching this? Is this problem possible? If it matters, I'm sourcing my equations from Anderson's Fundamentals of Flight, Ch. 1.


texts: What is this aeroplane - not a Blackbird?

texts:
What is the aeroplane in the first image?

I noticed this photo in a youtube clip, and at first glance thought it was a three-engine Blackbird SR-71, but it appears to be a single-seater.

The text and audio does not reveal what the photo is of.

  youtube.com/watch?v=nagVeYYt13s#t=10m41s

Some googling suggests that is a D-21 drone atop a M-21, and wikipedia has this somewhat-unhelpful photo.


texts: How do I request a touch and go and then remain closed traffic?

texts:
When I first contact a tower to request touch-and-go, if I want to remain closed traffic after the touch-and-go, can I say
'...tower, call sign, location, inbound for touch-and-go and remain closed traffic'?

I learned touch-and-go yesterday and I'm a student pilot in the US.


texts: Can I use audio containing Canadian ATC/broadcast radio transmissions in a YouTube video?

texts:
I often record my flight training without audio and post some of it to YouTube. I would like to add in audio recording of what I hear and say over the radio as well, but my ground school suggested that it was illegal to make radio transmissions public. On the other hand, I see youtube videos all the time that do include ATC voice traffic.

Can someone clarify for me if it is permissible to record and make public radio transmissions recorded during my own flights?

If it makes any difference, my videos are not/will not be monetized and and my flight training takes place in Canada.

EDIT: finally remembered my source, which is the radio operator restricted certificate study guide, which says:

Radio operators and all persons who become acquainted with radiocommunications are bound to
preserve the privacy of those communications. In accordance with subsection 9(2) of the
Radiocommunication Act, no person shall divulge the contents, or the existence, of communications
transmitted, received or intercepted by a radio station, except as permitted by the addressee of the
message or his/her accredited agent, or to authorized officials of the Government of Canada, officers of
the court or an operator of a telecommunications system as is necessary to forward or deliver the
communication. These restrictions do not apply to a message of distress, urgency, safety or to messages
addressed to “ALL STATIONS” (i.e. weather reports, storm warnings, etc.).
As outlined in section 9.1 of the Act, any person who violates the privacy of communications is liable,
on summary conviction, in the case of an individual, to a fine not exceeding twenty-five thousand dollars
or to imprisonment for a term not exceeding one year, or to both, or, in the case of a person other than an
individual, on summary conviction, to a fine not exceeding seventy-five thousand dollars. https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/sf01397.html

It sounds like I am able to post radio communications for which I am the addressee (and presumably addressor)


texts: Which fonts were used in old (1930s) aircraft cockpit displays and instruments?

texts:
This is probably more of a graphic design question than aviation but maybe a few hangar rats around here know the answer.

What type fonts were used on the old instruments in aircraft from the 1930s like Lockheed Vegas, Electras, Beech Staggerwings, DC-3s, etc.?  I need it for a web site I’m working on.


texts: How does the EPR reading behave in reverse, and in reheat modes?

texts:
Will an engine pressure ratio indicator (EPR) show the same at full mil thrust as with full reversed thrust?
What does the EPR indicate at afterburner active? Will it just show the same as for max mil thrust?


texts: Why is a blunt trailing edge a better stabilizer at hypersonic speeds?

texts:
Here is what I read about the X-15 spaceplane:

The X-15 had a thick wedge tail to enable it to fly in a steady manner at hypersonic speeds.[14] This produced a significant amount of drag at lower speeds;

A wedge shape was used because it is more effective than the conventional tail as a stabilizing surface at hypersonic speeds. A vertical-tail area equal to 60 percent of the wing area was required to give the X-15 adequate directional stability.

The X-15 does indeed have flat trailing edges on its stabilizers. Some photos show this.

So why does this produce better stability at hypersonic speeds? I thought stabilizers were more about the total surface area anyway. It just seems so counter-productive to make a flat end like that giving huge drag, especially for hypersonic stuff.


texts: What is the appropriate airfoil config for Raked Wingtips?

texts:
I'm doing a research about wingtip devices and while I'm searching about raked wingtip, I've wondered what is the best airfoil configuration for it?

Should it be the same as the whole wing?

My study is for application on aerodesign models that should have a low weight and carry a lot of weight.


texts: Why do planes always land on rear wheels instead of the nose wheels?

texts:
Various times, I have seen and felt myself that the plane always lands on the rear wheels, but not the front wheels. Why do the pilots land it on the rear wheels instead of the front? Does it have some advantage to it or is it a rule?

Is this required for all the planes (irrespective of size, type) to land only on the back wheels?


texts:
Obviously 100LL is risky. It's got lead in it, so there's going to be some danger. But is it possible to not get lead into my system when I start flying?
It is, for obvious reasons, something I wish to avoid. I want to learn to fly, but after reading the SDS for 100LL, I'm pretty worried. Here are the hazard and precaution statements for 100LL:

H225 Highly flammable liquid and vapour.

H304 May be fatal if swallowed and enters airways.

H315 Causes skin irritation.

H336 May cause drowsiness or dizziness.

H361d Suspected of damaging the unborn child.

H373 May cause damage to organs through prolonged or repeated exposure through
inhalation.

H411 Toxic to aquatic life with long-lasting effects.

P202 Do not handle until all safety precautions have been read and understood.

P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources.
No smoking.

P260 Do not breathe mist/vapours.

P273 Avoid release to the environment.

P280 Wear protective gloves/protective clothing/eye protection.

P301+P310 IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician.

P331 Do NOT induce vomiting.

P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin
with water/shower.

P308+P313 IF exposed or concerned: Get medical advice/attention.

Some of that is common sense, but that's a lot of very concerning information. How can I avoid contact? It seems like there's not really a good way around it, but I'm really concerned and I want to balance minimizing risk with still being able to fly.
Can anyone offer some advice?


texts: How can an aircraft not fall into the sea after the arresting cable snaps during a carrier landing?

texts:
After watching that video, I can't fathom how in the world could the crew save the day. Can someone give the intuition on how did that happen?

Unfortunately, I am not in the aviation, but I recall from Flight Simulator that on landing, the aircraft has such a small value of velocity. Maybe the aircraft carrier was tall enough and/or wind was helping that day?


texts: What is the maximum allowed intensity for light beams pointing at the sky for non-aviation purposes?

texts:
In Hong Kong, I'm designing a show with light beams and i'm thinking using Robe Megapointe lights (https://www.robe.cz/megapointe/). I've been ask by the client to follow the aviation regulation. Though the aviation regulation doesn't give any figure, only subjective indications, and I have no idea if my lights are acceptable or too strong.

The website of Robe announces: 2.200.000 lx @ 5 m and 137.500 lx @ 20 m. I'm trying to find similar regulation references in other countries to make up my mind.

Any of you have seen any figures in that domain?


texts:
I was under the impression that things like this:

and soon this

and even this

Are drones.

When and how did the media and the general public get the idea that these:

Are also drones?

I'm not going to argue with the fact that the label has been given.  But remote controlled quad coppers are just another type of remote controlled aircraft, what makes them different from RC planes and RC helos?  (Nothing.)  So why are they being deliberately group with full sized military aircraft that are used for killing terrorist and patrolling dangerous regions?

So, while RC quad copters have been labeled by the public and the media as "drones" are they really?  What makes "a drone" really a drone?


texts: Why do some non-towered airports have class E airspace from the surface up?

texts: I've noticed that when it comes to non-towered airports, some are in class G airspace and others have class E airspace starting from the surface. At first I thought the airports with class E at the surface might be in that configuration because they have precision approaches, but then I found exceptions where the airport has class G at the surface along with a precision approach. Is there a particular reason some non-towered airports are in class E while other are in class G?


texts: Are there any lift or lift coefficient equations which factor in the flap deflection angle?

texts:
I'm asking this because I tested a NACA 2412 wing with an adjustable flap in a subsonic wind tunnel and I'm getting the lowest Cl values for the highest  flap deflection angle.. which to my knowledge is theoretically wrong.

The inlet velocity is 15m/s. What is worrying me is that for a flap angle of 0 degrees, my cl value is a maximum. For 22.5 degrees, it gets less, and then for 45 degrees, it is the least. So the relationship is basically the inverse.
Note: the wing flap deflection is just to change the deflection angle of the flap; the wing area remains constant.

I'm guessing this could be due to increased turbulent flow after a certain flap deflection angle. That angle is what I am trying to determine.


texts: What is the purpose of the inlet doors of the Pratt & Whitney JT3D?

texts: I have a question about the 707 Engine Inlet Doors, according to Wikipedia the Pratt & Whitney JT3D inlet doors purpose is to provide additional air. Is the thrust higher on more air intake? And why modern engines don't have it anymore?


texts: How are cruise missiles different from ballistic missiles?

texts: Cruise missiles and ballistic missiles are used by many nations as offensive and defensive technology. How do cruise missiles and ballistic missiles maneuver, and what are the differences between the basic principles of these maneuvers?


texts: Is a physical lapel pin awarded for FAA Safety Wings?

texts: I have recently got my PPL, and started the FAA Safety Wings program. After completion of each phase, are we awarded a physical lapel pin?


texts: Does the co-pilot still remain in control of the plane if an engine fails during takeoff?

texts: If an engine fails after $V_1$, how long does the copilot remain in control if he was the pilot flying? What is prioritized before the captain taking control of the aircraft?


texts:
Jet engines are designed to contain a fan blade failure, and the engines and airplanes are designed with this type of failure in mind. This is more critical in the modern high-bypass designs with large fans. Pictures from bird strikes sometimes show pretty severe damage, but I don't remember any that actually lost a fan blade.

How often does a jet engine actually lose a fan blade?

This is different from a rotor burst, which is uncontained (like with Qantas Flight 32).


texts: Identify this Chicago aircraft incident involving loss of control

texts:
Many years ago I listened to an ATC tape of an aviation incident involving a commercial aircraft that had some type of control loss, I think in Chicago. After several attempts to set up for an approach, the aircraft landed safely. Despite extensive searching I haven't been able to identify the incident. Can anyone help?

Here's what I remember about the incident.

I am not thinking of United 232.
The aircraft had some kind of control problem - I don't remember exactly what the nature of the problem was (hydraulic / flight control issues).
It was a commercial aircraft.
It happened at least 10 years ago and possibly more.
I believe, but am not positive, that the incident happened in Chicago and the aircraft landed either at O'Hare (KORD) or Midway (KMDW).
A video is/was available that included ATC conversation with the aircraft. The video also showed a radar replay/simulation.
The aircraft makes several attempts to set up for an approach, circling around a few times.
The controller had to assist the pilot with establishing and maintaining the glide path, and at some point someone makes a comment about flying like the space shuttle.


texts: At what point is a turbine powered ducted propeller considered a turbofan?

texts: Turboprop Propellers can be ducted for extra thrust.  What are the criteria for determining that the engine is no longer a ducted propeller design, but a turbofan? Does there have to be a type of blade design, a fully separate nacelle/pod, number of blades?  Or are all turbofans technically shrouded propellers with some augmented thrust from the turbine exhaust ?


texts: What is the takeoff thrust of a CFM56 engine?

texts:
So, to be more clear I currently have an assignment about the Boeing 737-800.
I have to find out the total takeoff distance of the aircraft. I'm using Anderson's book " Aircraft Performance and Design" and I'm quoting that a turbofan engine is affected from the velocity of the aircraft.
Anderson uses this equation: T = k1 - k2*V + k3*(V^2) where k1,2,3 are constants from engine to engine. At his example he uses a Gulfstream IV aircraft and takes the constants as below (chapter 6, example 6.6):
The constants are selected for the takeoff phase. I guess that these values come from the manufacturer but I cant find this type of info anywhere. Not even a number about the takeoff thrust. The only thing that I can find is the maximum takeoff thrust which is the max thrust available from the engines.


texts: Is there a physical argument for the Kutta-Joukowski theorem?

texts:
I am doing the following exercise:

Consider inviscid, incompressible, steady flow. The Kutta-Joukowski theorem $$L' = \rho_\infty V_\infty\Gamma$$ where

$L'$ is the lift per unit span
$\rho_\infty$ is the freestream pressure
$V_\infty$ is the velocity
$\Gamma$ is the circulation taken around the body

was derived exactly for the case of the lifting cylinder. Equation $L' = \rho_\infty V_\infty\Gamma$ also applies in general to a $2$-dimensional body of arbitrary shape. Although this general result can be proven mathematically, it also can be accepted by making a physical argument as well. Make this physical argument by drawing a closed curve around the body where the closed curve is very far away from the body, so far away that in perspective the body becomes a very small speck in the middle of the domain enclosed by the closed curve.

And here is the solution from the author:

The flow over the airfoil can be syntheized by a proper distribution of singularities, i.e, point sources or vortices. The strength of vortices, added together, give the total circulation, $\Gamma$, around the airfoil. This value of $\Gamma$ is the same along all the closed curves around the airfoil. In this case, the airfoil become a speck on the page, and the distributed point vortices appears as one stronger point vortex with strength $\Gamma$. This is exactly equivalent to the single point vortex for the circular-cylinder case, and the lift on the airfoil where the circulation is taken as the total $\Gamma$ is the same as for a circular cylinder, namely, equation $L' = \rho_\infty V_\infty\Gamma$.

Author's figure:

I understand the author's solution until the part that said:

the lift on the airfoil where the circulation is taken as the total $\Gamma$ is the same as for a circular cylinder.

The equation $L' = \rho_\infty V_\infty\Gamma$ is derived from the circular-cylinder case which we have to do the integral of the pressure distribution over the cylinder surface. But I have not understood why the lift on the airfoil is the same for a circular cylinder like author said.


texts: What can I do if my carb-heat cable breaks in-flight?

texts: If I'm flying in conditions that are conducive to carburetor icing, and my carb-heat cable becomes in-operable, is there anything I can do to prevent engine failure if my carburetor starts icing up? Assuming there are no immediate landing-areas to stop and fix the problem.


texts: What do airliner manufacturers do with aircraft for which have no buyers?

texts:
"White-tail airliners" refers to either airliners without any customer order (like the beginning of A300 production), or those where the order was cancelled after/during production and where no new purchaser has been found (like the Skymark A380 deal).

How do the manufacturers handle the white-tail airliners?


texts: How are credit cards processed during flight?

texts:
If telephones/smartphones/tablets are not allowed on planes, how comes when you buy duty free items from the cabin crew and pay by cc they will use the card reader?

I suppose that in order to remove credit there must be some sort of connection to the various credit cards circuits in real time in order to achieve this?


texts: Why can't some airports handle heavy aircraft while others do it easily (same runway length)?

texts:
As I've seen in this video, they operate flights from Bournemouth airport all the way to Barbados on a Boeing 787-8. As Bournemouth runway length is 2,271 m (7,451 ft), it can handle aircraft such as Boeing 787 fully loaded.

In Kiev Airport (Zhuliany) in Ukraine, runway length is 2,310 m (7,579 ft). But the maximum it could handle is an Airbus A320.

Airport authorities keep telling us that they need more money to extend the runway length. And after that they will be able to handle larger airplanes such as the Airbus A321, but still not as big as the Boeing 787.

Another city is Kherson (Ukraine), the runway is 2,500 m long and can only handle the Airbus A321.

Are the local authorities misleading the passengers? They keep telling us that they need more investment/money. It looks like they are lying to us.


texts: With similar weapons why does an AH64 Apache require a pilot and gunner when the A10 Warthog only needs a pilot?

texts:
The Apache has a 30mm chain gun. It carries Hellfire (anti armor), Stinger/Sidewinder (air to air) and Hydra (air to ground, APKWS guidance package available) missiles.

source

The Warthog has a 30mm gatling gun. It carries Maverick (30cm air to ground including armor), Hydra (70mm air to ground) and Sidewinder missiles, plus a variety of bombs.

source

The Warthog seems to have a more capable and complex weapons load, so why doesn't it use a separate gunner like the Apache?

From comments:

The ULB (Unmanned Little Bird) version of the AH6 can fly with two, one, or zero pilots, so it seems that helicopters can be automated like fixed wing aircraft.

source

The Kiowa Warrior 50cal machine gun was not turret mounted; it was fixed to the airframe like the A10, though not buried in it. This is used in an armed recon role, not attack.

source


texts: Where does the term 'steam cockpit' come from?

texts: Why are traditional style cockpits with gauges called 'steam cockpits'? Do the instruments actually run on steam?


texts: How can the pilot tell the center engine failed on a piston aircraft with three engines?

texts:
There are a few aircraft, such as the Britten-Norman Trislander, that use three piston engines -- one on each wing and one mounted along the centerline somewhere.

This is fine and good, but how do you tell in a timely fashion that the #2 (centerline) engine has quit?  The engine gauges are in no hurry to tell you, as per Randy Sohn's Warbird Notes #6, and there's no adverse yaw because it's a centerline-mounted engine, but you still need to know and quick because unless you can get that prop feathered, there's a giant drag bucket hanging off your vertical tail!


texts: What is this Airbus A320 passager seat part?

texts: I'm on a Airbus A320 anyone have any idea what the black part on the back of the passager seat is used for?


texts: How many planes do ATC controllers assist in taking off/landing each day?

texts: I know controllers have several short shifts each day with interval breaks but I was wondering how many planes they assist in taking off/landing depending on what type of controller they are each day? Locational wise perhaps LHR? (London Heathrow)


texts: What is the purpose and history of the FAA's tracking system for handbooks and manuals?

texts:
Handbooks and manuals published by the Federal Aviation Administration usually have a designation attached to them. For example, the current Instrument Flying Handbook is designated FAA-H-8083-15B at the time I am writing this.

One apparent purpose of this system is to keep track of what particular version of is current.

What is this designator's proper name? What is the history of this scheme and can anyone shed light on any other purposes it may have?


texts: May a VFR-only pilot without high-performance or complex endorsements be the safety pilot for an IFR currency flight?

texts:
For an IFR currency flight in a high-performance and/or complex airplane where the pilot flying has all the appropriate ratings and endorsements to be PIC, does another pilot with strictly a private ASEL certificate meet the legal requirements to be the safety pilot?

If so, I would assume the entire flight must be conducted in VMC. What other constraints or restrictions apply in such a scenario?

If permissible, how may the safety pilot log the flight so as to count toward future ratings and so on?


texts: Are runway safety areas for both emergency landings and aborted take-offs?

texts: Is a runway safety area at the end of a runway provided specifically for safe emergency landing of aircraft using it and are required to abort takeoff just before or after reaching the critical V1 speed? Does it mean that at big international airports with a number of runways, each and every runway is to be provided with its own runway safety area?


texts: What are the main obstacles to becoming IFR-rated in USA?

texts:
Compared to getting a PPL, is it hard to become IFR-rated in USA, and if yes, why?

I recalled from the late 90s and early 2000s a statistic that said there are two GA accidents every three days.

And from a quick research into VFR into IMC, it turns out "nearly half of all weather-related accidents happen as a result of continued VFR flight into instrument meteorological conditions (AOPA)."

Revisiting the former statistic, it turns out for GA, "There is one fatal accident involving LOC [loss of control] every four days." And "a failure to recognize deteriorating weather continues to be a frequent cause or contributing factor of accidents (FAA, 2018)."

Combining the AOPA and FAA figures, and sad as it is, one can say that once every week or two, a fatal GA accident happens due to entering unanticipated IMC.

I'm hoping for an answer based on studies or experience (which may even draw from knowing VFR-only pilots who did not become IFR-rated, an experienced CFII for example). The reason I ask, I'm looking for some explanation to that statistic, by starting with the obstacles to getting IFR-rated.


texts: Are there all terrain landing gears for planes?

texts:
Is there a landing gear set up that will allow a single engine plane (also, allowing for tundra tires than what is not available for current water skids) to land on rough grass and water?
The wheels in the picture folds back to not case drag in the water; maybe the water-skid for a plane could work in this way for tundra tires?
Like this pictures landing skid but with tundra tires instead of those little ones.


texts: What is the average angle planes wings they need to fly?

texts: The planes I am talking about are everyday passenger plane's, not fighters. Do you know what the angle needs to be for it to create enough lift so the plane can fly?


texts: How to read the pressure diagram of an airfoil?

texts:
According to most authors, "lift is the result of the difference of pressure on airfoil sides".

My question is not about how this difference is generated, but only about the representation of the pressure around the airfoil. In particular, diagrams like this are frequently seen when talking about airfoils:

From Bernoulli or Newton's Laws for Lift?

Being not an aerodynamics engineer, I'll like to understand what can be deduced from this diagram.

Does this diagram indeed shows the variation of pressure on the contour of the airfoil ? Will this vary if the angle of attack or the speed are changed?
Is it correct to deduce from this diagram that the points on the red portion undergo a pressure smaller than free airstream static pressure, and those on the blue portion undergo a pressure greater than free airstream static pressure?

What is the correct method to obtain the relative pressure at a given point p1? Is it to measure the length of the segment which is perpendicular to the airfoil surface at point p1? What is the scale?

On the figure above, is p2 absolute pressure indeed equal to free stream air?
Do point p2 and the similar one found on the trailing edge have specific names?
What other elements can be deduced from the graphic?


texts: If the pilots used the brakes upon landing, would the force essentially slam the front wheel down?

texts: So if the pilots braked immediately, with only the back wheels down, and nose wheel still up, would the force from braking cause the front wheel to come slamming down?


texts: Why does Lift and Drag calculation over an airfoil ignore shear stress?

texts: why in Lift and Drag calculation over an airfoil we ignore shear stress effect and focus on pressure distribution?


texts: Does anyone know what this approach chart symbol is?

texts:
Does anyone know what the little “shell” like symbol on the taxi diagram is, under the 2239? Also, what do the little “P”s stand for? One is bolded and the other is not.

The 'shell' and the two 'P's are marked with red arrows in this diagram:

http://155.178.201.160/d-tpp/1809/05475R30.PDF

I’ve scoured FAA guides trying to locate what it could be, but so far, no luck.

Any help is appreciated!


texts: How does a flux gate compass system work?

texts:
I have heard of gyroscopes and AHRS being used for heading indication, but I haven't heard of a flux gate compass system until recently.

What are the principles of its operation and what types of aircraft or systems are currently using it?


texts: How are aircraft shipped to their customers?

texts:
This is sort of the inverse of this question.

I was looking at the Boeing facility in Renton, WA in Google maps, and I realized, the airport is across the (Cedar) river from what I assume to be the construction facility. The Boeing facility in Everett, WA is also across Highway 526 from the airport. That prompted this question: How is an airplane that just finished getting built (in any facility) delivered to the airline that bought it?

This question is targeted at large passenger aircraft being delivered to airlines.


texts: What should a pilot do to perform a successful emergency water landing?

texts:
What should a pilot do to perform a successful emergency water landing, also known as ditching of a big commercial jet?
Is there any checklist, or best practices, like "elevate the nose" or "retract the landing gear", to make it safer?
Are commercial Jets buoyant?

ditching http://www.flightglobal.com/blogs/wp-content/uploads/mt/flightglobalweb/blogs//learmount/Ditching.jpg


texts: How does Boeing Deliver single aisle jets to South east Asia?

texts: I am not sure if they can fly on full tank gas to their destination (say India or Thailand), but how does Boeing deliver single aisle jets to these destinations. I read somewhere about the process of delivery, but I am more interested to know what kind of skip hop flights do they take for delivery? Any way we can track new outgoing aircraft?


texts: How can an up-lifting tail have normal force direction and gradient when generating UP force?

texts:
This article includes this statement about tail forces to validate the concept that the horizontal tail in conventionally tailed aircraft can be generating force DOWN or UP at different times and still have normal stability and control characteristics:

  I took a Cessna 172 Skyhawk and put a couple of large pilots in the
  front seats, with no luggage and no other passengers. That meant the
  center of mass was right at the front of the envelope, so the tail had
  to produce considerable negative lift in order to maintain
  equilibrium. There was lots and lots of angle of attack stability. I
  took the same Skyhawk and put a small pilot in the front seat, a
  moderately large mad scientist in the back seat, and 120 pounds of
  luggage in the rear cargo area. That put the center of mass right at
  the rear of the envelope, so the tail had to produce considerable
  positive lift in order to maintain equilibrium. The airplane still had
  plenty of stability. (As far as the pilot could tell, it was just as
  stable as it ever was.) The easiest way to determine whether the tail
  lift is positive or negative is to observe the direction of motion of
  the tip vortices, as discussed in section 3.14. To observe the
  vortices, I attached a streamer of yarn, about half a yard long, to
  each tip of the horizontal tail, at the trailing edge. The streamer
  gets caught in the vortex, so its unattached end flops around in a
  circle. When the tail is producing positive lift, the circular motion
  is in the direction shown by the green “circulation” arrows in figure
  3.29, i.e. downward on the inboard side. When the tail is producing negative lift, the direction of motion is the other way, i.e. upward
  on the inboard side.

Numerous posts on ASE, and too many comments to count, support this concept.  That's great.  There is a nagging problem though that prevents me from accepting the "consensus" just yet.

For the tail to generate downforce, local flow must be above the zero lift line of the tail airfoil.  The hinge moment imparted by air loads on the elevator is TE down, control stick forward, and aft stick force is required to counter it.  For trim, the tab must move TE down to apply a servo force UP to counteract air loads.
For the tail to generate upforce (lifting), the local flow must be below the zero lift line of the tail airfoil.  The hinge moment imparted by airloads on the elevator is now TE UP, control stick aft, and FORWARD stick force is required to counter it.  For trim, the tab must move TE UP to apply a local servo force DOWN to counter act air loads.

This is what you would call "stick force reversal" and I can't find any resources that say this is a good thing; actually quite the opposite, and I certainly wouldn't want to experience it in my own airplane.

So how exactly does that work?  How can a lifting tail still have normal control force direction and gradients, same as a downforce tail, and how could the trim tab work given that it now has to work in the opposite direction to provide the required servo forces for trim, on the same aircraft?


texts: Is this a very sloppy holding pattern or something else?

texts: This scheduled Belavia service to Barcelona appears to be in a very sloppy holding pattern where they aren't correcting for wind at all. Is it normal for a passenger jet to fly like this?


texts: This is Goat3 ultralight with sweep cables,what is the fuction of these sweep cables?


texts: Do left and right mic buttons control both headset microphones?

texts: The aircraft I was flying today has a push to talk integrated button on each control yoke. I was sitting in the right seat, but my headset was plugged into the jacks on the left side of the cockpit. When I pushed the right mic button, the tower could hear a carrier wave but no voice transmission.  It was only when I pushed the left mic button that they could hear my transmission. Is this normal?  Seems like pushing either mic button should allow a transmission from either headset.


texts: Which pilot license is required in the US to engage in glider towing?

texts: As a former member of a US glider club (I live in Europe now, and it's all winch launches), I always thought being a tow pilot was a good way to build time. Can a private pilot tow gliders in exchange for money or credit with the club, or is a commercial ticket needed?


texts: How is the marine perimeter of a coastal airport secured?

texts:
Nice Côte d’Azur Airport is bounded on three sides by the sea, which is infested with oligarchs screaming around in powerboats and industrialists on huge yachts, all in close proximity (meanwhile the airport is full of their private jets).

A lot of this and other incessant marine activity takes place within swimming distance of the edge of the airport itself. The airport looks remarkably vulnerable to someone who could in effect simply swim up to the edge of the runway.

How is the security of this apparently porous perimeter, and that at other airports in similar positions, maintained?


texts: How should a loss of communications in VFR be dealt with?

texts: Let's say I'm flying a cross country flight and I wanted to land in a Class D or enter Class C towered airport, but I lost my two-way communications radio but have my transponder squawking 7600. Should I blindly continue in and receive light gun signals to land or should I steer out the Class C and D and divert to a non-towered airport? In worst case scenario, what if my transponder is also out?


texts: How does the mounting location of a jet engine affect aircraft performance?

texts:
Different jet airplanes mount the engines in different ways.

For example:

Under the wing

To the fuselage

How does the engine location affect aircraft performance?  Is one better than the other?


texts: Is it allowed to fly a right traffic pattern when a left traffic pattern is published (IFR)?

texts:
Allentown Queen City airport (XLL) has a VOR-B Circling approach procedure from the west.  Circling south of runways 7/25 is not authorized ("NA").  If the wind is favoring runway 25 is it legal to circle north under IFR using "right" hand traffic and land on runway 25 considering the following?:

XLL does not have a control tower and is in Class G airspace (uncontrolled airspace).
It is published that runway 25 uses "left" traffic.
FAR 91.126(b)(1) requires that all turns be made to the left unless airport displays (light signals or visual markings) show turns should be to the right.  This is NOT the case for XLL.

VOR-B approach:

Map of XLL in Class B Airspace:

Traffic Pattern Info for Rwy 25:

FAR 91.126: (full regulation here)