texts:
I have a friend that is considering putting his Navion on floats. A huge challenge. I recall having seen a photo of a Navion on floats, an old black and white photo, but I can no longer find it. If we can find it, it would be very helpful as he might be able to look up the N number and get FAA records on the engineering, etc.

Can anyone help in find information on Navion float conversions?
Any thoughts on a Navion on floats?


texts: Russian-built and NATO (USN, European) probe-and-drogue -- are they interoperable?

texts: Considering the current diversity of coalition air fleets in some parts of the world (the Horn of Africa situation comes to mind), can Russian-built tankers refuel NATO probe-and-drogue receivers, and vice versa? (Say, a US Navy F/A-18E getting a helping hand from an Indian Air Force Il-78MKI, or an Ethiopian Air Force Su-27 filling its tanks from a Royal Australian Air Force A330 MRTT?)


texts: It was developed by British Airways and Air France in the 1970s as the first supersonic passenger/civilian airplane.


texts: Does the weather condition of the runway affect the braking of an aircraft with regards to wheel braking and reverse thrust?

texts:
I was on a 737 that landed on a snowy runway in northern Finland the other day. We had to wait around 30 minutes to land as they were waiting for it to stop snowing and then for them to clear the runway.
The landing was fine but it felt like they used a lot of reverse thrust when landing. Admittedly, it's been 10 years since I last flew, but it got me wondering; in the event of such  conditions, would a pilot use reverse thrust more than wheel braking?


texts: What approvals do I need for a helicopter landing?

texts:
I have a horrible conflict; my sons are graduating on the same day at about the same time in different states. One in East Greenbush NY the other in Beverly MA.

I am interested in hiring a helicopter to transport us from NY to MA. My question is if I receive permission from the schools to land what other permits or steps would I have to take?


texts: What is the most effective way for a VFR pilot to scan the instruments during manoeuvres?

texts: May I ask your opinion on what is the best and most effective pattern for a VFR pilot to scan their instruments during manoeuvres?


texts: Is there a special ULD to be loaded at the main cargo door?

texts:
Watching this video, it appears that the hydraulic ram intrudes into the cargo space and would run into the Unit Load Device (ULD) that was stowed there.

Is there a special ULD that is loaded on each flight to clear the ram, or is there enough clearance that any ULD will fit in this spot?


texts: What are magnetrons installed on aircraft used for?

texts:
I'm interested in characterizing the radio signatures of magnetrons that appear to be installed in most large aircraft, some examples appearing on this list:

http://www.mpdcomponents.com/pdfs/FAA-PMA.pdf

My understanding is that these magnetrons were the first form of radar, but other technologies have largely supplanted them. However, they still seem to appear in the parts lists of modern Boeing and Airbus jumbo jets.

My question is what are these magnetrons used for, and when they are used, how they are used? Do pilots still use these regularly?


texts: Why do most commercial aircraft have their fuselage over the wing, instead of under?

texts:
Almost all commercial jets today seem to have the fuselage/cabin mounted above the wing, why is this? why isn't it mounted under the wing like some freight airplanes?

Examples of above and under?

The related post, What are the pros and cons of high-wing compared to low-wing design?, does not address the passenger airliner related aspects.


texts: Why do airliners still have a switch for the non-smoking sign?

texts: I've wondered why airliners have a switch in the cockpit to turn off the non-smoking sign. Why isn't it illuminated all the time, or a better question: Why is it still there, now that everybody should know.


texts: Is it allowed and safe to carry a passenger / non-pilot in the front seat of a small general aviation airplane?

texts: Is there anything wrong with taking a friend in the copilot's seat of a small general aviation aircraft with me flying, or does he have to sit in the back (if there is one)?


texts: How can we calculate the benefit gained from taping glider wing roots?

texts:
Most (all?) glider pilots will be familiar with the practice of taping wing roots.  As most of the gliders in my glider club (and I would guess, in the world) are stored with the wings detached, the practice of taping wing roots to close the gap between the wing and the fuselage is one which is hard to get through glider training without learning.  Indeed, even the type/brand of tape used can be a subject of hot debate.  This picture shows what a taped wing root looks like:

I've always wondered though how critical this practice is.  The gap in wing roots, once spar pins have been inserted, is typically pretty small.  I've forgotten to tape, but I usually don't forgot, partly because I know someone in the club will point out that I've forgotten and a fresh debate ensues.  I would say I'm currently skeptical (but open minded) about the benefit of doing this.

Question:

How effective is taping wing roots?

Lets take, for example, the Schempp-Hirth Open Cirrus, which has a published maximum glide ratio of 44:1.  Lets assume this glide ratio was calculated with the wing roots taped.  This assumption is bolstered by the fact that the rigging check list (Open Cirrus Flight Manual, Page 20) has taping the wing roots as a step.  What would the glide ratio be reduced to if the wing roots are not taped?  I do understand that the answer would depend on the width of the gap.  Lets assume that is 1/16th inch (1.5 mm) for this example.

Secondary Question:

What would the answer to the same question be applied to the gap tape used between the aileron and the wing, as is shown in this picture:


texts: Why are there 40 737 Max planes in flight when they have been grounded as not airworthy?

texts:
Many countries have already grounded 737 Max planes and as of Mar 13, 2019 the FAA have stated:

  The FAA is ordering the temporary grounding of Boeing 737 MAX aircraft (PDF) operated by U.S. airlines or in U.S. territory. The agency made this decision as a result of the data gathering process and new evidence collected at the site and analyzed today. This evidence, together with newly refined satellite data available to FAA this morning, led to this decision.

Source FAA Statement on Boeing 737 Max

So why are there currently 40 737 Max planes in flight according to FlightAware?

Who would be liable should one of these flights crash on takeoff, potentially over a densely populated urban environment?


texts: How is altitude reached by aircraft flying above the stratosphere measured?

texts:
Aircraft flying above the stratosphere (above 30km) are rare, but there is still the X-15 and the spaceship two. For those aircraft, maximal altitude is measured to within 500 ft.
As described in this question, barometric altimeters are not accurate nor practical that high. Yet, those aircraft are aircraft and as such I expect them to be fitted with barometric altimeters.
How is altitude measured with such precision (X-15: 354,200 ft in 1963, 15 years before GPS)?


texts: There's an airfield somewhere in the United States with a metal runway. Where is it?

texts:
Somewhere in the United States, there's an airfield (probably military) with a runway made entirely out of metal.  I've seen the approach plate for it, but I can't remember the identifier.

What airfield am I thinking of?


texts: How does a taildragger steer (taxi) differently to tricycle gear?

texts: I'm aware that there is a difference of some sort. Does a taildragger inherently require more room than a nose gear to taxi around a corner?


texts: How is airbrake function performed on the Dassault Rafale?

texts: At the end of airshow display (just before landing), the dassault rafale seems to slow down very quickly as it reach the top a final loop. It seems as if the pilot apply full airbrakes, but it seems there is no special flight control surface deployed to perform this function. How is this feature performed? Is it a special configuration of the split elevons? A combination of elevons and canard?


texts:
A few weeks ago, a storm passed through my area with winds reported at 55kt and gusting to 68kt.  Many light planes managed to break their tie-down ropes and were flung around the ramp area, which isn't surprising given the storm's winds were definitely above a typical light plane's VS0, VS1 and VR, possibly above VREF, VX and even VY.  Pilots being pilots, though, there were soon jokes about being able to take off and land vertically.

I understand that actually trying this would be a very bad idea, even before one considers the other aspects of the storm, e.g. lightning, rain, hail, low visibility, etc. that would make flying unsafe anyway.  I would never even think of trying it.  Still, it seems like an interesting theoretical question.

Is it even theoretically possible to "land" or "take off" in such winds, at least within the usual meaning of those words?  I can see that you could fly to touchdown easily enough, but how would you stop flying?  How could you taxi and secure an aircraft when you need significant power just to not go flying up (and probably backward) off the ramp?


texts: Why is this airplane flying in circles randomly?

texts: This G650 has been flying around for over an hour now.  Is this somebody with a mechanical problem who is burning fuel before returning to their airport of origin?


texts:
I did the majority of my PPL training in a PA28 Warrior and I've recently started transitioning over to a C172 and one thing that amazes me is how convenient it is to have a door either side of the aircraft.

My question is: Why does the PA28 only have one door on the passenger side of the aircraft?

I've never seen the schematics of a PA28 but my assumption might be that there's equipment that runs down the left side of the fuselage preventing a door from being added.


texts: What does a pilot mean when he tells ATC that he "has the numbers"?

texts: What does "have the numbers" mean when talking to ATC?


texts: May airlines cancel unprofitable flights?

texts:
If a given flight is unprofitable for an airline (occupancy ratio or – more precisely – revenue from ticket fares and cargo below the break even point) and if operating this flight incurred a bigger loss than cancelling it ...

May the airline cancel the flight ? (If no, why not?)
Will they ? (If they may but won't, why not?)
May/will they state the true reason or seize a pretext (e.g. technical defect) ?

Please distinguish between scheduled flights and charter flights.


texts: Is it legal to fly in RVSM airspace with an inoperative autopilot?

texts:
FAR Part 91, Appendix G, Section 2 says:

  (c) Altitude-keeping equipment: All aircraft. To approve an aircraft
  group or a nongroup aircraft, the Administrator must find that the
  aircraft meets the following requirements:

  ...

   (2) The aircraft must be equipped with at least one automatic altitude
  control system that controls the aircraft altitude

Note that it does not say that it must be engaged, or even operative.  Simply "equipped", and also that this is to approve an aircraft for RVSM.  From what I can find, there is no operational requirement for the autopilot to actually be working or engaged.

Assuming that my MEL allows me to defer the autopilot and still fly, can I fly in RVSM airspace?  Some people however say that if you are in RVSM airspace that the autopilot must be working and engaged.  Right or wrong?


texts: How is an aircraft designed to be longitudinally stable?

texts: How do aircraft designers ensure that a specific aircraft is longitudinally stable? Are there any different considerations for subsonic and transonic aircraft?


texts: What can airline pilots do if they are no longer in the position to fly, career-wise?

texts:
I was having a discussion with a friend about the incident in the past days (4U 9525) and more specifically the what could be described as 'Taboo' of Psychological problems among pilots. We came across a few points:

They will only reluctantly admit that something is wrong, since risk losing their Medical (hence being 'grounded'). It will only be easier to loose and harder to get back I suspect after this event.
At least for the younger bunch who might have difficulties they will have substantial debt from training that is difficult to pay off. Furthermore, they will have worked hard to get where they are.
Any airline that does suspect something will most probably not allow them near the cockpit again. Should anything happen the airline will be held to blame, since they did allow him to fly despite knowing of the problem.

This brings up the question: What can a pilot do, career-wise, if they feel they are unable to exercise the profession? It seems pretty cornered to me. Perhaps work in dispatch/ network control was the only one I figured their knowledge could come to use. Switching to the simulator I suspect might also be possible, but not for the younger individuals.


texts: Is there an explanation for the measurement system used in aviation?

texts: Why is speed measured in knots (as opposed to kmp/h or mp/h), and distances in nautical miles? Is there a reason for following such a system?


texts: In a pattern, when do you begin your descent from TPA if following another aircraft?

texts: I had always been taught to begin a descent from TPA abeam the touchdown point, even if tower tells me to follow another aircraft. Yesterday I flew with an instructor who did not want me to descend from TPA until abeam the aircraft I was following. I understand that I begin my base turn when the aircraft I am following is abeam my wing. I did not know to also wait until then to descend from TPA. It does make more sense to stay at TPA until this point but I can't find anything saying one way or the other.


texts: Do/why don't spaceplanes suffer from flutter?

texts:
Spaceplanes tend to have beefier, stiffer parts than normal aircraft, at least partly due to drag-reduction being less of a concern. But they also experience far higher airspeeds during reentry.
Yet I've never heard much, if anything, about flutter, or any other form of aeroelasticity being a problem on any of them. Maybe that's because I don't know much about existing or past spaceplane programs? But still, I'd be interested to know.
I can imagine some candidates for the reason why flutter might be less severe:

the frequencies are so high and modes so many and so uncoordinated that too much energy is dissipated as heat and sound, leading to simply vibration with no damage.
the sheer stiffness of the vehicle moves flutter frequency out of reach. (Which sounds rather far-fetched for me)

Hoping to find an answer, I Googled about aeroelasticity of the Shuttle, and got this document. It's rather long, so ATM I haven't drawn any conclusions from it.
It would be nice if someone has any background info on what the designers of the Shuttle (which I would guess is the best known spaceplane) faced during development in relation to flutter.


texts: Can a pilot still land if the tower gives confusing Information?

texts:
Recently an airplane crashed at Kathmandu airport in Nepal. The people that owned that plane claim that confusing information was given to the pilot by the control tower, and as a result the plane crashed. Conversation between pilot and control tower given here.

Now my question is: if confusing directions are given by the control tower, what should a pilot do? Should they wait for the exact decision and continue flying, or can they decide to make the plane land safely?


texts: What is that decommissioned plane near Nadirgul Airfield?

texts:
This is a decommissioned plane that I found at my place. I'm guessing it is a Dakota DC-47.

The plane is placed near a small airstrip called Nadirgul (name of the location), which lies in the outskirts of the city Hyderabad, India


texts: As a US citizen living in Europe, must I use a trust as the owner of an N-reg aircraft?

texts: I have found lots of information online about European pilots owning and flying N-reg aircraft using trusts set up in the US. I live in Europe, but I'm a US citizen, so must I also set up a trust because I don't live in the US? I cannot seem to find a definitive answer on this with references to supporting regulation.


texts: How does skydiving flight cause shock cooling?

texts:
While answering this question (How can reducing power too quickly on a piston engine damage it?), barit1 said that:

  Skydiving planes see a LOT of shock cooling, and they pay for it at overhaul time

What exactly happens during a skydiving flight which causes a lot of shock cooling?


texts: What is the parasite drag for Airbus A320?

texts:
What is the parasite drag or CD,0 for the Airbus A320?
How do we calculate CD? Is it correct to use CD = CD,0 + ( CL2)/$\pi$AR


texts: Why don't Russian aircraft sell as much as their European/American counterparts?

texts:
Are there any reasons other than political why Russian jets don't sell?

For a case study, let's compare Sukhoi Superjet and Mitsubishi  Regional Jet. Despite being delayed several times, Mitsubishi has secured more orders than Sukhoi. Similarly, Embraer and Bombardier aircraft sell much more than the Sukhoi Superjet. Many new airlines continue to go to with Embraer and Bombardier. Despite promising lower running, maintenance, purchasing costs, why doesn't this aircraft secures orders?


texts: What integration of aircraft propulsion would be more efficient at sea level high speed flight? A turbofan, unducted fan or a turbojet?

texts:
For educational purposes I am designing a small single seat twin engine aircraft that will be as efficient as possible at sea level and at a variety of speeds 150-500+ mph. The goal is to be able to travel long distances at high speed while offering great acceleration and loiter characteristics.

All of the information I've found is regarding cruising altitudes where at speeds of 400mph or less the turboprop is more efficient then a turbofan.

The chart below shows the results at altitude.

My top two choices are a variable pitch unducted fan or a high bypass turbofan. Both would be mounted in the wing with unducted unit having the blades aft of the wing. Both could possibly include afterburner for accelerating to top speed.

None of these charts take into account the drag of the different sized engines and their respective arrangements. The TSFC is usually quoted at design intention or static thrust and not sea level at high airspeeds so it's hard to compare known engines.

The turbofan aircraft could likely be designed quite a bit differently as you could use thrust vectoring and a variable nozzle reducing the number of necessary control surfaces and therefore drag which is extremely important in the thicker atmosphere.


texts: Do helicopters need to use yaw pedals to fly a coordinated turn?

texts:
I recall years ago, when I took a helicopter tour, I noted the pilot simply moved the cyclic left or right to bank the helicopter and initiate a turn. No pedal input was made whatsoever, and the ride seems completely fine.

In many fixed wing aircrafts, if rudder is not applied during the entry of a turn, the airplane will have a tendency to yaw to the opposite direction due to the drag induced by the ailerons.

Is pedal (rudder pedal? what are they called in a helicopter?) input necessary for turns in a helicopter?


texts: Weather sensors required for ILS approach operations?

texts: Was flying into Sullivan County this weekend and had to run the RNAV instead of the ILS. ATC advised there was a NOTAM for the weather sensors (which we had already confirmed.) Does an ILS approach require that the airport have functioning weather or is this just a case of a 2-for-1?


texts:
How hard would it be to convert a glider into an powered electric aircraft?
I'm thinking something that looks like this:

Would it be as simple as mounting two electric motors and props to the wings and plugging it into power the electronics and a battery system?
Any thoughts?


texts: Am I required to have my Radiotelephone Operator's Restricted Certificate (Aeronautical) on-board the aircraft with me?

texts:
Is there a Canadian law or regulation which requires me to have my Radiotelephone Operator's Restricted Certificate (Aeronautical) on-board the aircraft with me?

This is what I've found so far:

Canada requires you to hold the certificate (Radiocommunications regulations, Part V, Section 33):

  A person may operate radio apparatus in the aeronautical service, maritime service or amateur radio service only where the person holds an appropriate radio operator certificate [...]

However, I can't find a regulation saying I need the piece of paper with me.

An example of the wording Canada uses in its regulations to say that you need to actually have the document with you is at CARS 401.03 (1)(d) (regarding pilot licences):

  the person can produce the permit, licence or rating, and the certificate, when exercising those privileges.

I can't find that wording or anything like it relating to my radio operator's certificate in the CARS, the Radiocommunications Regulations, the Aeronautics Act, or the Radiocommunications Act.


texts: Can an airliner land safely using only propulsion control?

texts:
In this amazing story ,after losing all hydraulic power of the aircraft , Captain Al Haynes guided the plane to the Sioux city, crashed but saved 185 of the 296 lives (United Airlines Flight 232-Sioux City, 1989). After this incident, NASA started to work on PCA systems.

Gordon Fullerton landed an F-15, using only engine power. How did the F-15 land while the airliner crashed? Since an airliner and a fighter jet have different engine positions honestly it would make more sense to me if the airliner made it to the ground but fighter couldn't because it has relatively greater distance between engines, so better capability of yawing and as a result of having a shorter wingspan a fighter needs to fly faster to stay airborne. I understand the weight difference, i understand the possibility of adverse weather conditions during 232 flight, but i still don't get how a fighter is more capable than an airliner.


texts: Horizontal stabilizers stall, so I was wondering, is it possible for an aileron to stall? If yes, at what angle of attack?


texts: Which authority is responsible for RT licensing in the Netherlands?

texts:
Which authority does issue the separate RT license for pilots in the Netherlands?

I had a conversation with Netherlands CAA and they could not help me.


texts: Why don't commercial aircraft adopt a slightly more seaplane-like design to allow safer ditching in case of emergency?

texts:
For example :

Why don't they have a more hydrodynamically shaped fuselage underside ?
Specifically for the aircraft that have their engines mounted under the wings, isn't this too dangerous for ditching ? As far as I understand when an engine touches water during ditching the whole aircraft would/could break apart ?
Or, couldn't they have some kind of (retractable) floats ?

I'm far from being an aviation expert myself, but I imagine some things like the above (or possibly others) could be done, in order to allow safer ditchings for commercial aircraft. Would all these be too costly for airlines ?


texts: Was there a design flaw in the fuel tanks of the MiG-15/17/19/21?

texts:
Wikipedia article on MiG-15:

  Another major design deficit was that the tank could develop under-pressure if more than half the fuel had been used, which could easily lead to tank implosions, destroying the aircraft.

MiG-17:

  Like its forebear, the MiG-17 inherited the major design deficit which could cause the fuel tanks develop to under-pressure if more than half the fuel had been used, which could easily lead to tank implosions, crushing the main fuselage of the aircraft mid-fight, with almost always fatal results.

MiG-19:

  Initial enthusiasm for the aircraft was dampened by several problems, the most alarming inherited from MiG-15/MiG-17 was the danger of mid-air tank implosions when more than half of the fuel had been used - the leaking fuel of the crushed fuselage fuel tanks located between the engines would then ignite, leading to a fatal explosion;

MiG-21:

  Additionally when more than half the fuel was used up, violent maneuveurs prevented fuel from flowing into the engine, thereby causing it to shutdown midflight.3 and risking tank implosions (a problem inherited from MiG-15/MiG-17 and MiG-19).

None of these entries has a citation.

I would like to know if these aircraft really did have a design flaw in the fuel tanks, and if so, what was it? What was wrong with the tank that made it susceptible to implosions once more than 50% of fuel was gone?


texts:
This question probably lies in the middle ground between Amateur Radio.SE and Aviation.SE.

I have seen a couple of videos where ham radio contacts are made with people on board a commercial aircraft while in flight. In one of the videos, contact is established trough the 2-meter band (VHF) with a passenger carrying his hand-held transceiver on board the flight, while in the other video, contact is made trough the 20-meter band (HF) with the captain of the airplane using the airplane's radio transceiver.

I am curious about what do regulations say in this regard.

Are ham radio contacts allowed from inside an airplane?


texts: Difference between general, airframe and power plant concentration courses

texts: Trying to enrol for an aircraft maintenance technician course but the options are three that’s general, airframe and powerplant concentration. With the general being an affordable course to pursue, will it be advisable if I choose that than airframe or powerplant and would it be enough to prepare me for FAA exams ?


texts: What is this hole in the nose of the A330?

texts:
In this question, there is an image of a ladder leading to some hole in the bottom of the nose of an A330. What is that hole for?

Source


texts: Where is the center of gravity on a tiltrotor?

texts:
From what I understand, the CG of full-sized fixed-wing airplanes need to be forward of the wing's center of lift for stability. But the CG of a helicopter must be directly below the rotors since it doesn't have a horizontal stabilizer to counteract the pitching moment.
So, where is the CG in a tiltrotor airplane (the kind that has its engines on the wings, such as the V-22 or the AW-609)?


texts: Why isn't an LPV SBAS approach considered a precision approach according to ICAO?

texts:
According to ICAO's classification, LPV SBAS approach is in the APV group, because it doesn't meet some specifications for precision approaches. But what exactly does it not meet?

Glossary:

LPV: Localizer performance with vertical guidance
SBAS: Space-based augmentation system
APV: Approach with vertical guidance


texts: What is the real impact of biofuels on aviation?

texts:
I have seen tons of initiatives about using biofuels (like the ASTM D7566), but it is operative at large scale?, there is background info about demonstrative flights, but I don’t see a manufacturer or airline that is making use of the biofuel in regular basis.

It is a viable way of operate or it is a nonviable idea?


texts: What knowledge is needed to build a small aircraft?

texts:
It is my dream to make a basic flyable small scale aircraft (the size of a model aircraft). What is the basic knowledge needed to be able get started in the first place?

In particular, I would like to be able to design and build aircraft that can actually fly, while understanding why it all works. I imagine that there is a need to study fluid mechanics, the structures of aircraft, and certain mechanical and electrical systems.

It would be really helpful if you can enlighten me, and help jump start the learning process. In particular, suggestions about learning resources would be appreciated.

P.S. I have at least first-year university physics and I am always learning more.


texts: The stack controller only controls one or two stack and release aircraft accordingly. Does any ANSP (air navigation service provider) provide this service?


texts: If the static port get blocked, and no alternate static air source is fitted, will the transponder keep provide mode C?

texts: If the static port get blocked for any reasons and the aircraft is not fitted with an alternate static source while in Mode C with SSR, will the ATC still get the height information from my transponder?


texts: Who manages International Airspace Traffic?

texts: For example, if a plane is flying from Amsterdam to Miami and is in the middle of the ocean, who manages that traffic? The ARTCC? Or the airplane just flies without communicating for some hours until it reaches an ARTCC area?


texts: Why doesn't the U.S. Federal Government auction their retired but memorable aircraft?

texts:
The U.S. Federal Government has scores of old aircraft waiting for dismantling. Why doesn't it auction some of them? Some people might be very much interested in planes such as the B-52, and would be happy if they get it at some considerable price (though, I have no idea what it may be!) to keep them as a memorabilia. Also, this and this suggest that civilians can purchase and fly military aircraft. So why doesn't the federal government give this a shot?

Source


texts: What is the reason for the detour flight route from AUH to BEY?

texts:
I recently flew from Abu Dhabi to Beirut and I was intrigued by the flight route. Instead of simply avoiding Syrian airspace (as would be expected) and flying across KSA, Jordan and Israel, we flew almost to Alexandria in Egypt before hanging a big right and approaching Beirut from over the Mediterranean.

Source: FlightAware, text added

Before the Syrian war the flight used to take 3.5 hours, now it's more like 5 hours. Can someone explain to me why the flight took this route? Is it because Sinai is now considered a no-go zone? If so why not fly over Israel? Is this because it's not allowed?


texts: Was there ever a fuel-injected Spitfire?

texts: I couldn't find one but did it ever exist? Would adding fuel injection have improved combat effectiveness or fuel efficiency?


texts: Can airlines schedule more flight arrivals than the destination airport capacity?

texts:
Takeoff and landing efficiency at an airport seems to depend on a number of factors, like number of runways and gates, infrastructure maintenance, weather, or even notorious traffic congestion in some areas.

Busy approach at Heathrow, Youtube

Is there some process to prevent airlines to schedule more flights than the destination airport capacity? e.g. some coordination between ATC, airlines, and airports management. If so, how are airlines requests handled, is there some rule for fair sharing of the most demanded time slots?


texts: Are there requirements for ice protection for general-aviation aircraft?

texts:
Does anyone know if any regulations exist making it a requirement for general aviation aircraft to have ice protection systems?

And any insights on why general aviation aircraft tend to use rubber boots and fluid based systems as opposed to electrothermal solutions?


texts: How do aviation engineers ensure that the landing gear opens every time, without fail?

texts:
This is mostly with respect to large commercial airliners. I mean so many things can go wrong, then how have the engineers designed it to make it fail-safe? Or is it a very simple trick.

Also, are there any new developments in this area of landing gear, like lighter gear, or fixed gear etc.


texts: After decades of solid research, mostly led by Robert J Englar, why is Circulation Control, the Circulation Control Wing not in use at all?

texts:
Any research on the CCW by Robert J Englar at Georgia Tech from the 60's into the 2000's.
Many papers have confirmed Englar's work and in many cases, advanced it.
This research has proven extreme lift for slower, safer airliner take-off and landing as well as reduced weight, noise and drag.
https://smartech.gatech.edu/bitstream/handle/1853/14123/naqvi_messam_a_200612_phd.pdf This paper covers much for the practical use of a CCW but also references Englar's basic idea as well as posting several references to Englar's research.  These can also be covered to help answer my question.


texts: How important is it to have talent to become airline pilot?

texts:
The situation that led me to ask the question is as follows:

I am a student pilot with only about 10 hours of flight time. I passed the aptitude and personality tests prepared by German Aerospace Center (German: Deutsches Zentrum für Luft- und Raumfahrt).

My instructor keeps on telling me since the very first couple of flights that I lack some talent and it's not really possible for me to become an airline pilot. (He has never flown as airliner, only military aircraft but he is obviously a good pilot with long teaching experience.)

So, what is the possibility that he is right? How much and what type of talent is required?

Please note that I haven't caused any major safety problems, and other students claim that they made pretty much the same mistakes I do.

Edit : Since some people misunderstood the situation, I'll clear some issues:
1-) I'm on some scholarship program of an airlines company. Money isn't an issue.
2-) I'm generally considered to be pretty smart.
3-) There's no reason that I could be discriminated by the instructor.


texts: The AFDS and A/T do not control to a speed which is less than minimum speed for the current flap configuration?

texts:
The AFDS and A/T do not control to a speed which is less than minimum speed for the current flap configuration. This speed is approximately 1.3Vs. Minimum speed, FMC speed, or selected speed, whichever is higher, becomes the AFS command speed. If actual speed becomes equal to or slightly less than the minimum speed the underspeed limiting symbol appears in the MCP IAS/Mach Display, and if operating in the V/S mode, the AFDS reverts to LVL CHG. The AFDS will also revert to LVL CHG from VNAV PTH, except when flying a level segment. [FCOM 4.20.36]

This paragraph is about the minimum speed reversion function of the 737 Automatic Flight system. Can anybody help me understand the first sentence? I don't understand what "control to a speed" means here. Does that mean the AFDS and A/T do not "respond" to the speed??


texts: What variant of Mi-8/Mi-17 is this near Kennedy Space Center?

texts:
A tweet by Julia Bergeron showing pad activity near Kennedy Space Center also showed what seems like an unusual visitor for the area.  I've attached the relevant picture.  It's clearly in the same family as the Mi-8, but has the following unusual features:

The tail rotor is on the left, which I think places it in the Mi-17 (export) family?
The rear doors are a flat ramp, not a clamshell
There's a lump over the right door that might be a winch but also distinctly reminds me of the heater bulge forward of the right main landing gear on the Mi-8s that I'm used to, which this seems to lack?
It's a five-blade main rotor and three-blade tail rotor, so I don't think it's one of the newer Mi-38s.

The closest I've come so far is an Mi-17MD, but I'm not fully satisfied with that identification.


texts: What are the flaps on the exhaust of military airplanes for?

texts:
I have been looking over some pictures of military airplanes, and I noticed that some of the more modern air planes have flaps on the exhaust

I was wondering if anyone knew what the purpose of the flaps were, and why they are only on modern airplanes


texts: What is dual mode adaptive landing gear system?

texts:
Referring to the NASA document Design and Development of the Blackbird:
Challenges and Lessons Learned.
On page 31, there's a mention of dual-mode adaptive landing gear, which is quoted below.

Lockheed engineers designed a dual-mode adaptive landing gear system for the YF-12A. The configuration included a strut with an optimized air load-stroke curve during landing, and an automatic switch-over system to allow for a flatter air load-stroke curve during taxi. The study demonstrated the effectiveness of a dual-mode adaptive landing gear system in reducing the dynamic response of an airplane during taxi. It also provided a database to aid in determining the degree of correlation between analytically predicted responses and actual test results with a full-scale YF-12A.63

From what I could understand, it seems it's focus was to give the landing gear loading a smoother curve and reduce the dynamic loading during taxiing, in simpler terms, dampen the minor vibrations while taxiing.
How is this type of landing gear different from the basic oleo shock struts employed today, if at all there's any difference. I mean, it pretty much does the same thing. Is there any construction difference?
An image reference would very much be appreciated.


texts: Does an accelerating airplane also start climbing?

texts:
Assume that an airplane is flying level. If I understood correctly in this situations there are four forces acting on it: weight, thrust, drag and lift.

Lift depends on air density, airspeed, wing area and lift coefficient. In the situation described above all of these parameters are constant with the exception of airspeed which can be changed by pilot. So when increasing airspeed lift increases too which makes sense because that seems to be how planes take off.

However when you watch footage of airplanes accelerating (for instance when a fighter turns the afterburners on) they seem to be able maintain altitude.

At this point I see three possibilities:

The airplane doesn't climb or climbs very little because the pilot simultaneously compensates.
I have the wrong impression and the airplane does climb.
My reasoning above was wrong and there's actually no reason for the airplane to climb further.

So which one is it?


texts: Are there more accidents in winter months, and if so, why?

texts:
I was watching The Flight Channel videos and have noticed that the accidents seem to happen more often in winter months (for the Northern Hemisphere). Are there some statistics to back this claim?

It seems logical: Winter months means icing on wings, slippery runways, etc. Are there any not so obvious reasons for the increased accident rate during winter?


texts: Are crosswind landings easier with larger airplanes?

texts: I don't spot an answer to this question, so thought to re-post it here. Larger airplanes are heavier and would ostensibly be pushed less by the wind compared to a small airplane? Do larger airplanes have higher crosswind limits then?


texts: Why $\frac{\Delta p}{\overline q}$ is depending by weight, flap deflection and other parameters? Which are other parameters?

texts:
As you can see in this link (Roskam, Airplane Aerodynamics and Performance, Chapter 2.5.3 Airspeed corrections) ...

... in the first and second line of page 30 Roskam tells that, in hypothesis of incompressible flow $$ \frac{\Delta p}{\overline q}=\frac {\frac{1}{2}\rho_0V_c^2-\frac{1}{2}\rho_0V_I^2}{\frac{1}{2}\rho_0V_c^2} $$ " depends on factor such as weight, flap deflection and other airplane parameters ". Why does it depend on weight, flap deflection?

Which "other airplane parameters" do affect $\frac{\Delta p}{\overline q}$ ?

Note: for completeness of definitions, above in the same link, page 27  Roskam is defining:

"[...]  $V_I$ (IAS) is the indicated airspeed corrected for instrument error, $\Delta V_i$, only:

$V_I=V_i+\Delta V_i$      ________________$(2.54)$

$V_c$ (CAS) is the calibrated airspeed. It is equal to the indicator reading corrected for position error due to incorrect static port location $(\Delta V_p)$ and also corrected for instrument error:

$V_C=V_I+\Delta V_p$      ________________$(2.55)$ [...]"


texts: I know that magnetos are related to the engine and that on many planes, they are used to start the engine. But what exactly do they do in the engine?


texts: How might one fly from KRYN to SDRS in a de Hallivand DHC-6 Twin Otter?

texts:
First of all, this is not a flight I'm attempting myself; it's for a writing project. I myself have absolutely no knowledge at all of flight. The plane would depart from Ryan Airfield, Arizona (ICAO: KRYN) and land at Resende Airfield (SDRS). As the de Havilland DHC-6 has a range of only 886.7 miles, I assume a great deal of refueling is required. I have no knowledge of flight, so the logistics of a flight this length, (about 5,900 miles), in a light aircraft, are completely alien to me. Importantly, the passengers on the flight (4) do not have passports, but must still be able to enter the country. I’m guessing this means they’d land at a small airport/airfield. Assume the pilot has connections that allow his passengers to bypass any security at the small/private airport. The most important information would be: how long it would take, where/when they’d need to stop on the way, and where could the final destination be.

Your help is greatly, greatly appreciated! :)

Also, assume the situation is urgent and the pilot is a risk taker. He wants to get his passengers there quickly as possible.


texts: How do civil aircraft flying in formation handle ATC?

texts: I assume that while en route, one aircraft could simply pick up flight following and the others do not need to talk to ATC, but what about upon reaching an airport? Do they simply announce "flight of xxx 10 mi east with W for full stop" and get successive landing clearances, or do they all break apart before getting close to the airport? Thanks!


texts:
I notice that fighter pilots wear helmets, although pilots of aircraft like C-130s do not. What is the purpose of this?

I have heard that it could be helpful in the event of an ejection, but considering the explosive force of an ejection, if you hit your head I would be surprised if a helmet made any difference.


texts: Are centrifugal compressors/turbines less efficient internally, and if so, why?

texts:
From my related question which found a good example of a centrifugal turbine jet engine, the Henkel Hes 3.

Picture Source Website (it's in Czech). Thanks to Jan Hudec for finding it.
My understanding of centrifugal engines is that they have larger diameters and therefore larger nacelle drag, and therefore aren't favored.
So in this question, I want to ask, are centrifugal engines less efficient internally? That is, for a given thrust at given conditions, will the centrifugal have more, less, or equal fuel consumption than a "normal" axial-flow engine?
I can't imagine that friction of air flowing around a winding path, or related viscuous effects, could amount to any noticeable penalty. But I can't think of any other reason why centrifugals would be internally less efficient.
Note, another related question, one answer did say that centrifugal compressors will have higher losses than axial compressors, for a given compression ratio, but did not explain why.


texts: Why are planes using rivets & not welded construction?

texts:
I was motivated to ask by this question: Why are airplanes riveted and not screwed?

Why not welded construction? Is welding these alloys too difficult? I come from a refining background & in a lot of hazardous duties welded construction has become the norm because integrity is easier to guarantee than screws, bolts or rivets.

Just wondering what's different in aviation? Isn't repair, safety, weight & aerodynamics all better with a welded construction?


texts: Is it legal to takeoff in a crosswind that exceeds the design limit of my aircraft?

texts: Suppose the max crosswind rated for my C-182 is 15kts, but the wind is directly across and gusting to 20kts.  Is it legal for me to go? I've heard plenty hangar flying stories of many an operation that exceeds the design specifications of certain planes that end successfully.


texts: Can I get training in the USA with a PPL from another country, but without converting it?

texts:
My friend's in South Korea, and he would like to get training in the USA soon. He currently has a PPL in Korea and it is still valid.

I'm sure that he can start an IFR course in the USA and another country's PPL could be converted to an FAA PPL license.

First question:

I'm wondering if he can get flight training or just time-building with a non-converted license, i.e. just his Korean PPL?

Can he fly just with a CFI just as dual time? I'm sure that he cannot log PIC time if he doesn't have an FAA PPL. However, he would like to be familiar with USA PPL flying first before starting the IFR training.

Second question:

He will apply to the TSA first for time-building, but I'm not sure which category should be approved. There are category 3 (instrument rating) and category 1 or 2 (training event). Which one should he do?


texts: What is this odd large sign near Aalborg airport/millitary airport?

texts:
I have recently moved to Aalborg in denmark and while riding my bike each morning I cycle past these large signs pointing out into the water. I assume they are for aircraft at the nearby millitary/civillian airport because of how large they are and how they point directly out into the water in a relatively calm stretch of water on the edge of the city so nobody could see them.

The signs are quite large, about 1-1.5m in diameter and the poles are about 6 or 7 meters tall

The one interesting thing that made me think maybe its not to do with the airport is how it's actually quite far away (and also not lined up even slightly with the runway). In fact, they are almost perpendicular to the runway, about 4km away across the water.

I'd love to hear your thoughts on the matter, and apologies in advance if they turn out to be some other kind of markings. I am very curious to know!


texts: How late can a landing clearance be given?

texts:
I regularly fly VFR in an (EASA-) airport where the tower is sometimes rather busy and the frequency full which led a few times to me receiving landing clearances as late as 10-20ft AGL above the threshold.

I was wondering, if (EASA) regulations say anything about when you have to / should perform a go around on approach when you still didn’t get a clearance. I’m not asking about how to deal with those situations when flying, I’m just asking about what’s in the regulations about this.


texts: What do the different types of approach abbreviations used on the A320 MCDU exactly mean?

texts:
On the MCDU I have noticed after setting up the approach there are a number of different codes which appear next to the runway designator these are namely as below:
CI
CF
FI
CD
FD
Can someone kindly explain what these codes mean.


texts: Why is stabilator used in some small airplanes?

texts: What makes it so attractive to use a stabilator in some small airplanes like Piper Cherokee or Seminole? Its primary purpose is to allow the pilot to control a pitch movement with a less force (which I presume better serve big airplanes), and if so, wouldn't a horizontal stabilizer coupled with an elevator be a better choice for the manufacturers, especially given that a stabilator installed in small airplanes typically requires an antiservo tab to prevent overcontrol by the pilot?


texts: Where is the term *pro rata* defined as it is used in 61.113(c)?

texts:
You've just received your private pilot certificate and your friends want to share the operating expenses of a flight with you.  There's a mother, a father, and their 6-month old baby. Do you split the cost of the flight among three people or four?

Obviously, the answer depends on the definition of pro rata, but I can't find the definition of that term anywhere in the FARs. This term is used here:

  (c) A private pilot may not pay less than the pro rata share of the operating expenses of a flight with passengers, provided the expenses involve only fuel, oil, airport expenditures, or rental fees.

Where is the term pro rata defined as it is used in 61.113(c)?


texts: Can commercial automatic flight control fly back-side?

texts:
For most commercial flight director, autopilot and auto-throttle systems (e.g. the A330-300, B737-800), the flight director/autopilot flies the altitude hold (ALT) or vertical speed (V/S) mode by closing the flight path/altitude loop with pitch control, while the auto-throttle maintains airspeed. It's only in flight level change (FLC/CLB/DES) or go-around (GA) mode that the autopilot controls airspeed via pitch control and the auto-throttle controls a thrust rating.

Closing the loop around airspeed via throttle and closing the loop around flight path via pitch control work fine when the aircraft is on the front-side of the thrust curve. However, this control strategy leads to instability when flying on the back-side. While this scenario is not likely to be encountered in normal flight operations, the best climb speed for maximum weight would be pretty close to the boundary (with some margin built in by the manufacturers).

How do the automatic flight controls handle flying on the back-side? Or do manufacturers ensure that the floor speed/AOA for system engagement always have margin to the minimum drag?


texts:
The Instrument Procedure Handbook says on page 3-18

  "Arrival delays typically are absorbed at a metering fix. This fix is
  established on a route prior to the terminal airspace, 10000 feet or
  more above the airport elevation. The metering fix facilitates profile
  descents, rather than controllers using delaying vectors or a holding
  patterns at low altitudes."

I cannot get my head around this concept. So how does a metering fix work to absorb arrival delays? What's exactly a profile descent and how is it related to the metering fix? What merits does it have as compared to delay vectors and holds?


texts: What does the phrase “flight attendants: stand by for all call” mean?

texts: At the end of an announcement on a recent flight, a crew member said: “flight attendants stand by for all call”.  What did the crew member mean and what exactly were the flight attendants waiting for?


texts: What would happen if a pilot were to use the parking brakes after touchdown in order to slow down?

texts:
The situation that I came up with is merely hypothetical. Say a pilot was unable to land right after the runway threshold, for whatever reason it may be - a crosswind, etc - but was determined to land the aircraft.

I understand that most pilots would abort the landing and go around but say this one decides to land. However, it is too close to the end of the runway to stop just by using brakes, spoilers, and the thrust reversers. Could this type of landing (in an emergency) be achieved and by using the parking brakes what would happen if a pilot actually used the parking brakes to slow down?


texts: Can a UAV over 55lbs legally fly 20 miles off the US coast?

texts:
For US aerospace companies that are developing UAVs heavier than 55lbs for application for the DOD, is it possible to test UAVs over the ocean outside what we would normally consider US controlled airspace legally without a FAA specific exemption?

I should add that in this particular case the UAV can be launched and recovered from Sea.

Thoughts?


texts: When (if ever) can ATC order an aircraft to go around?

texts: Can ATC order an aircraft to go around if there is a tailwind? Or should ATC give the pilots the current wind information and let them decide whether to go around or land?


texts: Why is the clearance delivery frequency included on an approach plate?

texts:
Approach plates include frequencies in the order that pilots will require them, reading from left to right.

The example below from McClellan-Palomar’s ILS or localizer/DME approach to runway 24 is a fair representative. On the far right hand side just above the overhead view is the clearance delivery frequency of 134.85.

Talking to clearance delivery prior to departure is common, but when would a pilot talk to clearance delivery on arrival? What is the purpose of including this frequency on the approach plate?


texts: What are the disadvantages of a Tail providing lift? (tandem-wings included)

texts:
Most aircraft feature the tailplane configuration, which requires the main wing to provide higher lift than the weight of the plane itself, what seems counterproductive.

Few aircraft have featured tandem-wings like the Rutan Quickie, Proteus or the Maurice Delanne 10 with limited success. I usually read that the main disadvantage of the tandem-wing is that the rear wing is subjected to the downwash from the front wing, what greatly reduces its efficiency Q&A link.

My point it that standard tails suffer from the same downwash effect, and on the other hand this effect can be reduced by:

a T-tail
Making the front wing much larger than the aft-wing.

Thus, which are the flaws of this design (top)?
Given that it could still have the CoG in front of the Neutral Point.
Why are lifting tailwings refered as unstable? Q&A link
Is this layout suitable for VTOL aircrafts, in which horizontal take-off and landings are not an issue?

Thank you for your attention. I would appreciate remarks of any wrong assumptions.

Extra

Why the Proteus features a tandem-wing, and why this layout unusual?

Edit:
The reason for considering a lifting tail is that to make VTOL possible for this layout, the CG must be moved between the rotors, thus far aft.


texts: Could the Mars helicopter Ingenuity have been test-flown outdoors at JPL just for the heck of it? (not that they would)

texts:
The Ingenuity helicopter that has flown on Mars is designed for roughly 0.01 bar pressure and a colder atmosphere made of mostly CO2. See links (including video) in this answer to What JPL laboratory is this exactly, and what are the functions of these amazing-looking control panels? in Space SE and sources linked within. For more about Mars' atmosphere see this answer to What could Perseverance listening to Ingenuity reveal? there as well, and sources within.
The counter-propagating rotors (driven by separate motors but synchronized) spin at about 2500 RMP. The propellors are huge by Earth standards compared to the tiny weight that they carry. But we also have to remember that it will weigh more on Earth. See answers to Does Ingenuity rotate via differential rotor speeds or differential angles of attack? and sources within for more on that.
Question: Hypothetically, could the Mars helicopter Ingenuity have been test-flown outdoors at JPL just for the heck of it? Not that they would ever do such a thing (it will have been kept very clean and very very safe at all times) but from a technical stand point would it have flown? What rotor speeds and torques would have been necessary, and would these have been possible with the light-weight motors optimized for Mars flight?


texts: Is the Common Route, either of a SID or a STAR, related to the Runway Transition (climb phase) or the Enroute Transition (enroute phase)?

texts:
Based on this question ("What are the 'parts' of a SID procedure?"), I would like to ask for clarification concerning the role of the Common Route in a SID.

As far as I have understood, the most important part of the SID (the "runway transition" as it is called in the ARINC424 specification manual) is visualized with bold lines on the related charts. During this phase, the aircraft performs an obligatory climb with a minimum climb gradient of 200 ft/NM, unless otherwise specified. The remaning routes (common route and enroute transitions) are visualized with thinner lines and their respective Minimum Enroute Altitudes are also depicted.

What I find confusing is that the Common Route is sometimes visualized with bold lines and without Minimum Enroute Altitudes and other times with thinner lines and with their respective MEAs.

An example can be found if one compares FINZZ2 with EPKEE:

Is there a reason for having the Common Route sometimes as part of the Runway Transition (without MEAs) and other times as part of the Enroute Transitions (with MEAs)?

EDIT:

Τhe same distinction also applies to STARs, where common route can either be part of enroute or runway transitions. An example can be found here and here (OHSEA TWO Arrival, KSNA). Notice that common route is visualized with bold lines, same as runway transitions. However, most of the arrival procedures, as far as I can tell, use it as part of the enroute phase (containing MEA, drawn with thinner lines etc.).


texts: I'm doing a project in which i'm attempting to model the motion of a wing using a system of second order differential equations. This is a 2-degree-of-freedom model based on the quantities pitch, a(t), and plunge, h(t). I know what pitch is, but what is plunge? and why is it affected by pitch? Where do these equations come from?


texts: Which aircraft is a single-prop, low-wing aircraft with prominent rivets and three canopy windows?

texts:
We would appreciate help identifying an aircraft that my daughter saw. It is a single-prop, low-wing design with a round fuselage and very prominent rivets.

It had a prominent canopy that stood above the fuselage with visible windows, and the rudder was visibly slated as well.


texts: Could the wing struts on the SUGARVolt cause problems?

texts:
On Boeing's concept aircraft, the SUGARVolt, there are wing struts connecting the fuselage and the wings, which is for making sure that the wings do not bend too much during flight.

Could the wing struts cause aerodynamic instabilities, and could this make the aircraft more efficient, or less efficient? In what ways?


texts: Where does the Departure End of Runway (DER) exactly begin?

texts: I am having trouble understanding the concept of Departure End of Runway. Most sources state that DER is at the end of the portion of the runway that can be used for takeoff (which, as far as I can tell, excludes the threshold at the end of the runway). But from the official FAA's Aeronautical Information Manual one can clearly see that DER starts at the "utmost" end of the runway (including threshold). Many other sources seem to support this, like this picture. Could someone point me to the right direction?


texts: Which countries (if any) allow beyond-line-of-sight drone use?

texts:
I was recently thinking about starting up a non-profit that would use large drones (full scale aircraft, not those dinky quadcopters) to deliver humanitarian aid to difficult locations.

It was shot down pretty quickly when I remembered that civilians aren't allowed to fly unmanned systems beyond [the visual] line of sight (BLOS).

So, this led me to my question, are there any countries that allow BLOS use of civilian unmanned aircraft?


texts: Do raked wingtips reduce drag of a hang glider?

texts: Do they realy reduce drag or improve performance?  If so, how?


texts: Why was there a rattling noise coming from the left engine of A319?

texts:
I recently flew on an Airbus A319. When boarding the aircraft from the front entrance we passed in front of the left engine. The fan blades were spinning and there was a rattling noise (like when a chain is being rolled up) coming from the engine.

Is this normal? What causes this sound? Is it the fan blades that are somehow loose?


texts:
Reading about the 787 it says it has

  an active gust alleviation system similar to the system used on the
  B-2 bomber. [1]

The gust alleviation patent says:

  The gust alleviation system picks off the stick displacement signal
  and the aircraft normal acceleration sensor signal and processes this
  information. The outputs of the gust alleviation system are added back
  respectively to the existing flap command signal and the aircraft's
  original stability augmentation loop. [2]

As a layman I am not sure I fully understand this, so my question is, what is the gust alleviation system?


texts: Can Microsoft Flight Simulator help me learn to fly (or make me a better pilot)?

texts: Microsoft Flight Simulator has "flight lessons" with a virtual flight instructor, some of which teach concepts that are taught during actual flight training. These simulators are becoming very realistic, and I can see them being helpful as an introduction to a subject prior to running the Hobbs meter and paying for actual flight time. Will this experience help or hurt someone who decides to become a real pilot? Is it a tool which can help students/instructors in an actual training environment?


texts: Does the centre of pressure of a cambered airfoil go ahead of the quarter chord point when angle of attack is increased?

texts: I got two figures and answers which are seemingly contrary. In wikipedia, it says the the location of the centre of pressure of a cambered airfoil is just behind the quarter chord point at maximum lift or high angle of attack. But in other websites, I see the centre of pressure well ahead of the quarter chord point. Which of the below two pictures is correct?


texts: Would "Ground Control" be feasible for commercial aviation?

texts:
Would the airline pilots be able to get instant technical assistance from the ground?

Today, ground systems receive only a tiny trickle of information while the airplane is in flight. But with communication channels steadily improving (systems like 2Ku promise satellite bandwidth in 10s MBps range), we should be able to channel enough data to almost make the flight data recorders redundant.

Can we go one step further and set up a NASA-style mission control centers for commercial flights? The workflow should go approximately like this:

The plane is flying and constantly transmitting flight data to ground control center at low bandwidth (but still higher than is practiced today);
When plane's systems detect any kind of abnormal situation, data feed is switched to high-bandwidth, and ground control center is alerted;
Software at the ground control center processes the alert as well as expanded data stream and may decide to escalate the situation to human personnel;
Human personnel reviews the alert and may initiate a conversation with plane's pilots. Pilots can request assistance from ground control at any time;
Ground control specialists can request the plane to stream specific data, depending on situation;
In the end, instead of two pilots, whose training may be questionable, we have a team of specialists working to resolve the situation.

Today, air traffic control can help the pilots somewhat, but they don't have any data feed and can't help with technical issues. Airline companies
collect some flight data, but only a little. I don't know if it's a norm in the industry to maintain 24/7 "ground control centers". What is clearly different in my proposal is that pilots don't have to explain everything to ground control. Ground control would have all the data and should be able to advise pilots sometimes even before they are aware of any emergency.

Do you think the plan above would be helpful and technically feasible?

P.S. My question is different from "Could the CVR and FDR record to the cloud?" because I'm not looking for 100% data dump (transmitted data would always fit the available bandwidth) and actually look for a more advanced solution of taking a real time action by the ground control.


texts: Does the FAA restrict the color of pilot seat belts?

texts: In the US, is there a legal restriction to prevent the use of bright red pilot seat belts in GA aircraft?


texts: To what extent are (non-urgent) PIREPs used by meteorologists?

texts:
It's inevitable. At some point during your weather briefing, some underpaid, underappreciated briefer will say "Pilot reports are requested." and you'll say "Certainly, my good sir or madam! Why, the only thing that gets me out of bed in the morning is the chance to help my fellow aviators!" and then you won't make one.

But let's say that you do make a non-urgent pilot report.  Briefers will give that information to pilots, but what about the meteorologists who actually make the forecasts?  Supposedly, they're interested in the information as well...

  "NBAA is excited about the new electronic submission form that should streamline the PIREP process, and allow the information to get to the FAA air traffic controllers and the NWS Aviation Weather Center (AWC) forecasters sooner," noted John Kosak, program manager, weather, NBAA Air Traffic Services.  [1]

but what are they used for once they're submitted?


texts: How to go about designing a custom airfoil?

texts:
I am familiar with the NACA 4-digit and 5-digit airfoil design system where airfoils, but I was wondering if anyone had some good reference material or software for designing a completely custom airfoil.

From what I understand, many new aircraft use completely custom non-NACA airfoils, sometimes several different airfoils over the wingspan. I am curious about how the design process goes from specifications of the airflow (incidence angle, perhaps the sweep of the wing, air speed, density, reynolds number etc) to a new custom airfoil?


texts: What is this display on the 737 Classic?

texts:
Source: YouTube

I noticed that display (yellow circle) between the two CDUs. What is it for? It is not a default installation on the 737-3/4/500.

It looks like a Navigation Display/MFD, but why have it when the 737-Classic EHSI (white circle) under each EADI already overlays weather and traffic?


texts: What is the relation of stall speed to the position of the center of pressure with respect to the centre of gravity?

texts: Would the centre of pressure being aft or forward of the centre of gravity (CG), reduce or increase the stall speed in straight and level flight?  I know it is a weird question, I just cannot figure out if a centre of pressure being ahead of the CG (rare) would increase or decrease the stall speed, or even change it at all.


texts: Is on-board equipment for in-flight de-icing also used on the ground?

texts:
Aircraft operating in icy conditions are equipped with de-icing equipment to remove ice from specific parts of the aircraft (wing, sensors,...) in flight.

When there is snow or icy conditions while the aircraft is still on ground, it is de-iced with ground equipment (de-ice fluid, towel,...).

Is the aircraft's own de-icing equipment also used?

Is this equipment enough to de-ice an aircraft before take-off (lets say if this is a sunny day and the temperature is just below 0°C)?


texts: Why do some approaches have suffix letters such as Y and Z?

texts:
There are cases with instrument approaches where there will be multiple approaches to the same runway, in many cases uses some of the same nav aids and positions, but differentiated using alpha characters.

One example are the ILS Y or LOC Y RWY3 and ILS Z or LOC Z RWY3 approaches at Raleigh Exec Jetport at Sanford-Lee County in Sanford, North Carolina. These approaches both use the LOC/DME I-TTA there, and some of the same positions.

It seems that the differences are subtle in the overall procedure on things like the missed approach procedure and how positions are identified, but I'd love a textbook answer that explains it more thoroughly.

ILS Y and Z (click either image for higher resolution).


texts: In what way are the Concorde's engines considered efficient?

texts:
The Concorde is powered by a bunch of Rolls-Royce/Snecma Olympus 593 turbojet engines. Much has been said about how efficient they are at speed, and the fact that they allow long-range cruise at Mach 2 because of how fuel-efficient they are.

If I look at the specifications, one thing immediately obvious is the compression ratio of 15.5 - quite high for a no-bypass turbojet. I'm not sure how this translates into efficiency though.

The thrust-specific fuel consumption, on the other hand, looks dismal. Wikipedia states:

  1.195 lb/(lbf·h) (33.8 g/(kN·s)) cruise / 1.39 lb/(lbf·h) (39 g/(kN·s)) sl

Wait, what? The Tumansky R-25, which powered the MiG-21 and was famously fuel-hungry, had a compression ratio of only 9.5, but had a TSFC of

  98 kg/(h·kN) (0.96 lb/(h·lbf)) at maximum military power

The General Electric YJ93, which powered the XB-70 and was also designed for long-range supersonic efficiency, had a TSFC of

  0.700 lb/(lbf·h) or 19.8 g/(kN·s)

This doesn't seem to make sense: in what way are Concorde's engines any good? Is there something I'm missing?

Finally, I've been attempting to model the Olympus 593 in a flight simulator (Advanced Jet Engine in KSP). With the given compression ratio, though, I couldn't get the fuel efficiency to be this bad: it was around 0.9 SL and 0.85 cruise, and I had to do ridiculous things like using extremely inefficient intakes and nozzles.


texts: If the Captain's screens are out, does he switch seats with the co-pilot?

texts: If captain's screens are out, and let's say that the airplane is about to land and the captain is supposed to land it, will he/she switch the seats with the co-pilot? or does he/she depend on the small little analog gauges on his side?


texts: What is a Cessna 172's maximum altitude?

texts: What is the maximum altitude at which a Cessna 172 can fly?


texts: Sonic boom impediment to hypersonic passenger flight

texts: Given that the ramjet and scram jet engines could achieve hypersonic flight, is sonic boom the major impediment to passenger hypersonic flight today?  If so, why is it that space shuttles could travel at speeds in the regions of Mach 25. How did they deal with sonic boom in relation to noise pollution on the ground what was so unique about their design given that there were many space shuttle fights.


texts: Why would a Cessna 182T not enter a stall?

texts:
When I took delivery of a new Cessna 182T last year, I did a test flight for certification purposes. During the test flight we had to perform a power off stall but that didn't go as planned as it was simply impossible to stall. What happened is this: when the airspeed dropped well below the power off stall speed we simply started to sink slowly with a nose-high attitude at about 35 KIAS. This "mushing" went on for what seemed ages before I eventually applied power and pushed the nose down to gain airspeed again. We tried it again after that and the same thing happened. I had an instructor with me who has thousands of hours in a C172 and he had never experienced something like this before.

The odd thing is that this only happened during that flight. During later flights this didn't occur anymore.

There was a passenger in the back seat, fuel tanks only half full so the CG was more aft than usual, but well within limits

Ever since that flight I've wondered:

What could cause this to happen? (My guess is it is CG related)

And most importantly:

If I would have continued this "mushing" flight, would it be possible to have entered a flat spin or a simple "drop out of the sky" like the infamous Air France 447?


texts: What do pilots actually see through the windows?

texts:
As I have never flown inside a cockpit, but only played with simulators I find that the dashboard takes most of the field of view(or am I wrong?).

So what actually can pilots see given good weather conditions, especially during critical parts of a flight, like take-offs and landings ?

I'm generally interested in big airliners.

P.S. I am not asking if they could takeoff/land without visual contact.


texts: What would happen if the flight engineer is unavailable on a 747?

texts:
Consider a 747-100/200 with a 3 person crew: two pilots and one flight engineer. During the flight, the flight engineer suffers a medical problem and is unable to serve duty for the rest of the flight.

What difficulties would the pilots face for the remainder of the flight, including navigation and landing, with no one attending the flight engineer station in the cockpit?

For example, would one of the pilots get up and sit at the FE station, leaving the other pilot the only person at the controls? Or would the person get up, go to the FE station to read or adjust something, then sit back at the pilot's seat? Or do they not have to move at all?


texts: Does the Enroute Phase begin at a 30NM distance from the departure airport?

texts:
ICAO's Doc 8168 Volume II ("Aircraft Operations") states:

Part III "Performance-Based Navigation Procedures"
Section 1 "Underlying Principles"
Chapter 1 "RNAV Concepts"
1.2 "Flight Technical Error"
Table III-1-1-2. Phase of flight [...] En route (greater than or equal to 56 km (30 NM) from departure
or destination ARP. [...] Terminal (SIDs, STARs, initial and
intermediate approaches less than 56 km (30 NM) of the ARP).

A similar categorization can also be found in FAA's Order 8260.58A ("PBN Instrument Procedure Design"), which states:

1-2-5 "Obstacle Evaluation Area (OEA) and Flight Path construction"
b (2). Width. [...] For the en route transition, legs that cross a point 30 NM from ARP, the OEA primary area width expands or tapers at a rate of 30 degrees relative to course to the appropriate width [...] A departure or missed approach segment designed to cross a point 30 NM from the ARP more than once changes to RNAV 2/RNP 2/A-RNP (en route mode) and remains expanded when it crosses the boundary the first time.

They way I interpret the above instructions is that a departure procedure should end (either explicitly or via vectoring) at a 30 NM distance from the departure airport, where optionally the enroute transitions of the SID will guide the aircraft and prepare it for the cruise flight phase.
On the other hand, take FINZZ TWO where the distance between LGA airport and FINZZ is less than 15 NM, something that contradicts the aforementioned convention of 30 NM between the airport reference point and the start of the enroute mode.
Could somebody help me realize what I'm getting wrong?


texts: I've heard this term used to describe approaches into low weather (e.g. category 2 ILS), what is it?  How is this different than an ILS approach?


texts: What are these crevices below the wing of B-52 bomber?


texts:
When did the color orange enter flight test?  As early as the Bell X-1, pictured here, aircraft were painted orange to enhance visibility. Later, in 1959, a study was conducted that suggested the utility of orange markings on aircraft.  In 1968, the Society of Flight Test Engineers adopted a logo with "flight test orange" as its color.

There are, however, few references that explain the following:

When orange flight test equipment (wires, parts, LRUs, etc.) first appeared.  For example, I transcribed a 1977 article from the SFTE's Flight Test News that sets 1949, anecdotally, as the time/event that caused Douglas to use orange wire. But it also references a Mil Spec. (Does anyone know more about the Mil Spec referred to?
When orange flight suits first appeared?
When aircraft (in general) adopted orange paint schemes for flight test aircraft, as seen here?


texts: Why does the wing root of the A330 have a pronounced twist?

texts: just wondering what the purpose of the pronounced twist on the Airbus A330 wing root is,  I've noticed this on the 380 as well.


texts: Is there anything wrong with this more symmetric aircraft design, and why isn't it used?

texts:
I imagine a fixed wing airplane design that's a lot more symmetric than what I see today. This symmetric design has wings in the middle of the fuselage (neither high wing nor low wing), and the empennage is a symmetric cross. Two vertical fins, one on top and one on bottom, and two horizontal stabilizers. The tail fuselage would taper symmetrically too, instead of the underslope with flat top we usually see today. This would make the fuselage closer to a Sears–Haack body, which I believe is ideal.

In other words, it would look a lot like the XB-42 Mixmaster:

Ignore the weird engine. AFAIK, this design could use an engine anywhere. BTW, this is the only aircraft I know with the middle-wing and symmetric cross tail design—whether experimental or production aircraft.)

The reason I imagine this is so the control surfaces are much more aligned with the center of mass. So the rudders, elevators, and ailerons will not produce any adverse torques when used. I think this will be more efficient, especially when using trims, and also is a simpler design as far as I can tell.

To get around the problem of tail strikes, I imagine a single tail wheel attached underneath it. For small aircraft it might not need to retract. For larger aircraft, I don't know how or where it would retract to, but maybe instead some kind of aerodynamic shield can enclose/open around it, like a prolate or oblate spheroid shape.

(An alternate symmetric design would be an X-shaped empennage—same shape, just rotated 45 degrees. I think for a given yaw, the combination of control surfaces would produce more drag though, but it's a way to increase ground clearance.)

(A more exotic alternate might be to forget about takeoff rotation entirely, and just increase takeoff speed and the length required to literally lift off without pitching up the nose. This might not be feasible for large commercial aircraft though.)

(But maybe best is to add canards with their own elevators, or all-moving canards, which will push up the nose and pivot at the wheel.)

To me this symmetric design seems simpler and versatile. By versatile I mean it looks like it could be used for small and large aircraft, whether prop-engine or jet engine, military or civilian, and not really mattering where the engines are located either.

Is there anything wrong with this design? Why is it not used more often? In fact I do not know of a single production aircraft with this design.

If anyone knows of any aircraft in this configuration, whether experimental or production, please provide a link so I can read more about it and maybe discover some reasons for its success or failure.


texts:
While looking over an ILS approach chart,
I found that there is a fix where says : (IF/IAF) ACZUP ...

And I was consfused whether the two IF and IAF can be in the same place, or the spot is used as IAF or IF in a certain occasion.

Could anyone tell me which is the right thing?

(IF = Intermediate Fix; IAF = Initial Approach Fix)


texts: Do military pilots have a phrase like "aviate, navigate, communicate"?

texts:
The phrase "aviate, navigate, communicate" is commonplace among pilots, as a reminder to concentrate on flying the aircraft first, with navigation a secondary focus, and fitting in communication when it won't interfere with those other things.

Military pilots have other things to distract them from the primary focus on flying: tracking the target they want, keeping an eye out for other threats (not just collision threats), managing EM emitters or countermeasures, &c. Flying into a bad situation due to "target fixation" is not uncommon.

Do military pilots have any kind of drill, phrase, mnemonic, or teaching aid to set priorities for their flying, like "aviate, navigate, communicate"? To be clear, I expect they use that phrase for 'normal' flying, and I'm curious to know if there's an extra mnemonic about their combat-specific priorities; maybe something like "wingman, threats, targets".


texts: Is it possible to obtain an STC for single-pilot ops in a jet certified for two pilots?

texts:
I have been doing research on whether or not one could realistically obtain an STC for a super-midsize jet certified for two pilots and legally fly it single-pilot.

For reference, my chosen aircraft is the Hawker 4000, which can be had for significantly less than most jets certified from the manufacturer for single-pilot ops. Additionally, the Hawker boasts performance figures that laugh at all other light jet numbers and its Relative Value Analysis (RVA) is comparable to jets costing $25M+.

I cannot find information anywhere on gaining single pilot certification in any aircraft not originally certified for single pilot operations. I would even take into consideration the possibility of a complete retrofit of the flight deck with Garmin 3000 or some other system designed to be flown single pilot (like that in the Phenom 300).

Thanks!


texts: What happens to the spinning wheels of the landing gear after takeoff, before retraction?

texts:
What happens to the spinning landing gear right after V2 on takeoff? Are they automatically or manually braked to a halt before gear retraction? Or are they allowed to spin to a halt in the wheel wells?

I am asking this question in the context of common passenger planes, such as the Boeing 737-800 or the Airbus A320.


texts: Limitations of bird flight as an aircraft design

texts:
What is it that stops man from duplicating Bird Flight as Engineering?

After all, birds do not require separate propullsion! They use the same wings for propulsion and navigation.

My question could be broad. Is it far-fetched ?

With solar energy harnessed and electronic control systems, SHOULD we not take a re-look at bird flight, at least as personal carriers or even as a short-haul option ?


texts:
I have been trying to find some real numbers on how strong a single solid piece of aircraft graded spruce wood timber is, but haven't had much luck and the numbers that I have found so far were either not for aircraft graded spruce or the sources weren't credible enough or simply the numbers were conflicting with what else I had found previously.

My question therefore is: How much of an evenly distributed weight a piece of aircraft graded spruce can take e.g. as a wing spar or struts before structural failure?

The length and thickness of the timber doesn't matter as long as the spar and/or strut went under the load test alone. The reason that I'm saying this is that I can find numbers for aeroplanes that have spruce spars for example, and based on the maximum G, weight of the aeroplane, etc. I can have a rough guess for how much load the entire wing is certified for, but an entire wing is made of other components that will have an effect on the results of those tests, which means those maximum numbers may not necessarily be the limits of the spruce spar itself e.g. the wing ribs or wing surface might have a lower tolerance, therefore reducing the performance numbers in the certificate.


texts: Do IFR / VFR weather minimums include ceilings?

texts:
I'm not really sure how to ask my question, but there are classifications for weather conditions for MVFR, IFR, and LIFR. The FAA also has weather minimums for flying VFR in the different airspaces here.

What is the difference between when we would use one over the other? If I am departing from an airport in class bravo airspace, would I need three statute miles of visibility and remain clear of clouds (second link), or would I also need to adhere to the minimum VFR ceiling of 1000' (first link)?


texts: How does the ADS-B compact position report NL() function work?

texts:
I'm trying to decode ADS-B messages for a school project, and I cannot reproduce the results of the NL() function as described in this document. I've seen the same formula in several other documents. Also in this document is the reverse of this function - the NL is input, and the latitude "boundary" is the result. I cannot solve that either.

I've tried radians and degrees for the trig functions and several different calculation tools, and my result is never close to correct.

The "known" good inputs and result are from this document. I've also seen these inputs and results elsewhere, but no details about the equation itself.

The summary of the "known" good data set is:

$rLat = 10.2157745361328$

$NZ   = 60$

$NL   = 59$

The equation is:

$$
NL = int \left( 2 \pi \left[ arccos \left( 1 - { 1 - cos \left( {\pi \over 2NZ} \right) \over cos^2 \left( {2 \pi \over 180} \mid lat \mid \right) } \right) \right] ^{-1} \right)
$$

Can anyone help me understand this calculation?


texts: Why are expletives deleted in CVR transcripts?

texts: I was reading this when I envisioned this question. In this  age, I don't think expletives can offend anyone. They may not be germane, but oughtn`t authenticity outweigh relevance?


texts: If "all flying rudders" for LSA aircraft need up to 40% less area, what about "all flying elevators (stabilators)"?

texts:
If "all flying rudders" for LSA aircraft need 33%-40% less area than a typical vertical tail (stabilizer and rudder) ( subject to final stability analysis), what about "all flying elevators" (stabilators) with:

anti-servo trim tab?
no anti-servo trim tab?

I understand anti-servo tabs add stability to "all flying rudders/elevators" by auto-centering.
According to a design guide from Zenith: Flying on Your Own Wings, by Chris Heintz, pg 229:

The vertical tail area should be 12 to 15% of the wing area (15% if the rear fuselage has a small rounded section, and 12% if the rear fuselage has large flat sides). These percentages may be reduced to 7% and 10% for an "all flying rudder".

A wing is a wing, no matter what attitude, whether it be horizontal or vertical. So I should be able to reduce my horizontal tail area by roughly 33-40% when using only a "all flying elevator" (stabilator) (subject to final stability analysis).  Is this correct?
My personal view is that a Zenith can fly a lot slower with an all flying rudder, 39 mph or slower, and that is why Heintz recommends that based on the type of aircraft he manufactures: basically LSA types, @ 1320 lbs MTOW, 39-4 5mph stall speed. Somewhere I read that a Zenith 701 won a STOL competition in Australia with a 25' takeoff, and  that a 3 second takeoff is common and by the time you reach full throttle, you're aloft albeit still in ground effect.
I understand the Zenith CH200 had a classic vertical tail, but that most or all current designs use an all flying rudder.
Summary:
So I assume that Heinz's above recommendation is for sizing a rudder at a 39mph stall speed which would need to be bigger for slow speed handling than for a plane that stalls at 60mph.
Revised question: at 39 mph would an "all flying" elevator be more efficient, thus letting it be 33% to 40% smaller?


texts: How do airlines make sure that pilots remain skilled enough to operate aircraft? What quality assurance is there for certified pilots?

texts: What measures are in place to prevent pilots from being put in charge of passenger planes without an appropriate level of training and skill? Are these measures enforced equally by different countries, airlines and aviation authorities?


texts: Can I rent a Cessna for a week with my GF with a PPL?

texts:
I want to do a 45 hour course to obtain a PPL. The course only includes 10 solo hours but states that it is enough to hire light aircraft.

So could I rent a Cessna after this and take a passenger?


texts: Why do planes have cross-feed switches or circuits? Are they to move contents of one tank to another (feed the tank) or to supply the engine with fuel from left side to right or vice versa (feed the engine)?


texts: What is the relation between airspeed and generated heat at constant drag?

texts:
I understand higher speed, and higher drag mean higher adiabatic compression leading to heating up the air, and the plane as result. X-15 needed ablative coating to prevent overheating. On reentry of space vehicles heat shielding is the most critical problem. This is perfectly understandable as higher speed with constant or growing air density means higher drag - and this results in higher speed.

I'd like to know how are these values related though.

[for the purpose of this question, let's neglect the issues of engine efficiency. We have a magical rocket engine that weighs nothing and needs no air nor fuel to produce thrust. This is a purely an aerodynamics question.]

At given pressure, drag is directly proportional to lift (both being quadratically proportional to airspeed and linearly to air density). That means higher airspeed allows raising the altitude, lowering air density, and thus lowering drag until lift and gravity even out.

Let's maintain such a flight: We're constantly accelerating (slowly); and climbing, at such a rate, that lift remains constant, and evens out with gravity (minus a minimal delta to retain climb). The increase of lift coming from rising airspeed is being offset by decreasing air density as the craft climbs.

With constant lift, and drag being directly proportional to lift, drag remains constant too.

Maintaining constant drag through climb like that, air density is inversely proportional to square of airspeed.

How would heat creation behave in this situation though?


texts: Could a 'wind wall' help to reduce the wind shear problem at St Helena airport?

texts:
I've seen a fair number of articles online about "The World's Most Useless Airport" (St. Helena, HLE/FHSH), which was unable to open to full commercial flights (as was the intention) due to the wind shear that occurs there. Because of this, only small aircraft are allowed to operate into St Helena.

This may well be a completely impossible idea, but if the issue is wind shear could they not adopt a system similar to this 'wind wall' which they use to protect large cargo ships in canals in the Netherlands?

Obviously we are talking about aircraft here and not ships, but would an approach like this - diffusing the wind either side of the runway threshold - have any effect on the final stage of the approach, to the extent that the wind sheer becomes tolerable for 'standard' commercial air traffic? Obviously large concrete structures wouldn't be particularly sightly, but from a purely practical point of view would something like this alleviate the issue at all?


texts: Why does this statement about intrastate aviation in Alaska appear in airworthiness directives?

texts:
Airworthiness directives typically include a claim that they...

  Will not affect intrastate aviation in Alaska to the extent that it justifies making a regulatory distinction

What's the reasoning behind making this assertion?


texts: Do Grumman F-14s, Panavia Tornados, and other swing-wing airplanes count as "fixed-wing aircraft?"

texts: I'm just wondering because the wing isn't fixed, but they aren't rotary-wings either.


texts: Why does the B-29 not have pilot-accessible thrust?

texts:
Watching this incredible B-29 Superfortress flight, I was amazed to see that it required a dedicated person to manage the 4 engines and their power levels.

Why was the throttle not placed between the two pilots, like the modern airliners of today?


texts: Do military aircraft overflying other countries' airspace require special clearance?

texts: Is there any special clearance, when military aircraft will overfly other countries' airspace? Are they continuously monitored?


texts: Do the crew members in the plane have access to cargo area?

texts: I always thought that if there is fire ir something else happening in the cockpit, can the crew members go in cargo area to secure the place..


texts: Are helicopter with coaxial rotors equiped with blade flapping mechanism?

texts:
Helicopters with coaxial rotors such as the Ka-27 don't need mechanisms to overcome dissymmetry of lift as there is advancing blades on both sides of the helicopter. A common mechanism to overcome the dissymetry of lift on classic helicopters is the blade flapping as described here.

I see no need to introduce blade flapping on coaxial rotors helicopters, but there can be other reason to keep it I don't know.

Are helicopters with coaxial rotors such as the Ka-27 fitted with blade flapping mechanism?


texts: Is the elevator really an 'angle of attack control' as described in Stick and Rudder?

texts:
I've been reading Wolfgang Langewiesche's book Stick and Rudder and am a little confused about the definition of the elevator as the "Angle of Attack Control" or rather, the idea that each position of the elevator corresponds to a unique angle of attack.
I was under the impression that Angle of Attack is the angle the wing meets the relative wind. Consider a certain elevator position for straight and level flight at cruise rpm. If I then add power and climb (while holding the same attitude) isn't it true the Angle of Attack will increase because the relative wind is now coming from in front and above the plane? If this is true, then how can I reconcile this with the idea the elevator is an "angle of attack" control. Isn't the plane's Angle of Attack based on not just the position of the elevator, but the motion of the plane through the air?
If anyone could give me some advice to clear this up it would be greatly appreciated!


texts: Does the stator blade angle changes? Why?

texts: I have read that when jets are on the ground their compression ratio changes. With this change the stator compressor's blade angle changes. Is this true?


texts: Why do aircraft piston engines require priming?

texts: Aircraft piston engines generally require priming, but automobile engines don't seem to need it. Why doesn't cranking the engine with the starter pull in fuel mixture that would ignite without help of the priming?


texts: Can the wheel brakes hold an airliner in place if its engines are at full thrust?

texts: Are wheel brakes on most commercial jet airliners capable of holding the jet stationary on a dry surface, if all the engines are given full thrust? Could doing this be potentially unsafe or damaging to any of the aircrafts other structures,  such as pylons, wings, etc.


texts: Altimeter disagreement. What's the crew procedure to deal with that?

texts:
The crew is facing a situation, in which, the altimeters indicate different altitude (the port and starboard ones - cpt´s and FO´s). Is there any procedure to perform an IFR landing?
If we consider a light aircraft, what the crew will do?


texts: How can I find the maximum climb angle of a propeller driven aircraft from a graph of vertical velocity against airspeed?

texts:
I've been asked to find the maximum climb angle of a propeller driven aircraft from the graph of vertical velocity against airspeed:

How can I do that?


texts: What is the origin of the term "military power"?

texts:
An engine producing 'dry' thrust is said to be at 'military power', a useful distinction from reheat / afterburner.

It's always seemed an odd phrase to me. There's nothing particularly military about it, and why would afterburner not be military? 'Military' has always been used as a word that always relates to soldiering in some form or another - it is a curious choice to define the operation of a jet engine.

It must, of course, be a twentieth-century phrase. Can any light be thrown on its origin?


texts: Why are early wing planforms mostly rectangular?

texts:
I am looking at the history of wing planforms, and I am having trouble finding reasons for why the wright flier and other early aircraft were built with rectangular wings. I thought it was due to being more structurally secure, but I can't find any sources that explicitly say that, or describe the thought process of early designers.

Is my reasoning correct, and are there any other reasons for the decision to use a rectangular wing (vs a tapered wing)?


texts:
In the on-board magazine of my today's flight, there was a report on how fuel efficient the airline flies. They accomplish this by new scitimar winglets,  daily optimized route planning, and regular cleaning of the jet engines.

I never heard about this cleaning. How and how often is it done?


texts: When do commercial flights turn off the APU?

texts: On commercial flights do the pilots ever turn off the APU? Is it needed when flying?


texts: How minimum runway length is calculated for PAC P-750 XSTOL?

texts:
I'm not a pilot, but have interest in the question from a safety perspective, as a skydiver and drop zone operator.

I read the POH of PAC P-750 XSTOL, and tried reading a bit about the calculations, but could not make it out.

Given the parameters below, how is the minimum runway length is calculated for PAC P-750 XSTOL?

Parameters:

Pac 750 XSTOL
15 knots cross wind 90
0° flaps
6500 LBS TOW
Runway is 1500 feet above MSL
ISA +10°


texts: What is this turn called and how is it performed?

texts:
I've found pictures and videos of jets rotating 90 degrees so that one wing points straight down to the ground and the other is straight up, then they suddenly turn away from their course while remaining in that position.

Here's a video of that maneuver (link goes to 2:10).

What are the aerodynamics that can make this kind of turn possible? In a lot of YouTube videos this type of turn happens after aerial refueling. Is this type of turn possible on a large airliner, and if it is, when do pilots of this airliner ever use this method in flight?


texts: What is the minimum speed a glider can thermal at?

texts:
What is the minimum speed a glider can thermal (climb)at, typically, in terms of Vs over a dark field on a warm summer day?

Is it 1.1Vs, 1.2Vs, or 1.3Vs, etc,?


texts: Are high-frequency flapping wings efficient and scalable at high Reynolds numbers?

texts:
Is high-frequency flapping (similar to how dragonflies fly) an efficient lift production method at high Reynolds numbers?

I have not seen anyone develop wing suits with high frequency flapping, is it efficient only at the insect scale? A few million years ago there used to exist dragonflies with wing spans around 70cm - correlating with the high oxygen content in the atmosphere at that time - so is this possible at larger wingspans too?

I'm thinking of something like the parademons in Justice League:


texts: Does useful load increase with more horsepower?

texts:
If an engine's horsepower is increased will max gross weight be increased?

For example what is the effect on max gross weight of changing the engine on a small GA airplane from 65hp to 100hp.


texts: Where can I find a reliable database of civilian ATS Routes?

texts: I am looking for an updated source of ATS routes. Are there any free and reliable (ie produced by the FAA or Eurocontrol) datasets available?


texts: What is the history of this specific Cessna propeller (s/n F2430)?

texts:
Hoping someone can help... I'm looking to get some information about a Cessna plane propeller my Fiancé recently bought. It's his birthday coming up and it would be great to have any sort of history, photos or further info on his pride and joy.. The information on the propeller:

Cessna KLIPTIP
MET-L-PROP
MCAULEY, DAYTON OHIO
SERIAL NO- F2430
DESIGN 1A100 MCM 6950
T.C 918 P.C.3
I do have photos if necessary

I really would appreciate any sort of help - it would be great to give him a surprise.


texts: What are the Single European Sky (SES) and Functional Airspace Blocks (FABs)?

texts:
Air Transport World is reporting that the European Commission has initiated legal proceedings against Germany, Belgium, France, the Netherlands and Luxembourg; for not implementing FABs by the deadline. A quote says:

  FABs are a cornerstone of the SES initiative and are intended to reduce the capacity, cost and environmental constraints that continue to dog Europe's fragmented air traffic management (ATM) system by establishing common airspace blocks arranged around traffic flows rather than state boundaries.

What exactly are SES and FABs, in laymans terms?