texts: What is the effect of airfoil thickness on aerodynamic lift?

texts:
More than once I`ve read that the airfoil thickness contributes little to the lift compared to the angle of attack and airfoil curvature and has more to do with airfoil stall characteristics.

Could anyone explain this, preferably mathematically?

Thank you


texts: Why don't airplane piston engines have mufflers?

texts:
It is understandable jet engines couldn't have mufflers, but even long before the jet age, airplane piston engines never had mufflers the way cars do.
Is there any specific reason?


texts: Does a type rating give a person the privileges of an instrument rating in any category or class of aircraft which he/she is certificated in?

texts: Suppose someone obtains a PPL-ASEL, then obtains a type rating in an aircraft requiring that rating e.g. jet, etc.  This type rating functions as an instrument rating, allowing the pilot to fly the new aircraft under IFR.  But does said type rating then grant the pilot the privelages to operate ANY appropriately equipped airplane single engine land under IFR as well?


texts: Is there anywhere I can pick up raw flight data recorder information?

texts:
We were plotting flightpaths as practice in programming class but unfortunately that was limited to some recordings from a research aircraft.

I'm wondering if I can pick up the raw data files from (accident) Flight Data Recorders somewhere to see if I can plot them as well?

(Like a file with rows listing time, position, altitude, airspeed etc.)


texts: Does the movement of the magnetic poles affect aviation?

texts: Recently I read that Earth's magnetic pole moves quite significantly, several kilometers. Do these changes affect aviation, i.e. for pilots landing their airplanes?


texts: Can the Apache detect infrared (IR) lock?

texts:
Can the Apache, regardless if it's the AH-64E/D (US) or AH1 Longbow (UK), detect IR lock?

I am aware that the Wildcat AH1, Merlin HC3/4 and AH1 Longbow share the same defensive systems that can detect IR missile launch. However, I have yet to find any information suggesting any of these aircraft can detect an IR lock from a fire control system of another aircraft.


texts: What happens when disengaging the electricity generators on a B747?

texts:
This answer says:

  If let's say, you [...] disengage the electricity generator of every engine (which cannot be re-engaged without mechanical maintenance), [...].

What exactly happens in the aircraft when disengaging the generators and what benefit does it have to be not able to engage them again?
Is it only the B747 that works like that or also other Airliners?


texts: What are the differences and benefits between/of time-based vs distance-based separation?

texts:
This video suggests a time-based approach to landing aircraft separation is preferable to the distance-based standard commonly used.  It advertises a greater arrival volume at airports, as strong headwinds can delay the time between aircraft landing.

What are the pros and cons for a change in standard?  Under TBS, aircraft would be spaced more closely (distance-wise) on approach during strong headwinds.  Does this present a possible hazard to trailing aircraft if something goes wrong late in the approach (like this runway incursion?)


texts: Is the emergency fluorescent floor lighting strip along the aisle an item on the MEL?

texts:
Was travelling on a Airbus A320 (night flight) and during the safety briefing noticed that the  fluorescent floor lighting strip referred to in the evacuation instructions was totally absent.  Both sides of the aisle.

I could see the marks on the floor carpet where it must have been earlier tacked on. Was removed and went unreplaced for whatever reason.

Is it OK for an aircraft to fly without this item? Seemed pretty essential to me for a safe evacuation in the dark.

Edit: I did try & take a photo but unfortunately didn't come out so well.


texts: What is the difference between centre of pressure, aerodynamic centre and neutral point?

texts:
I have just started learning some aerospace concepts, and I am not able to understand the difference between the three terms centre of pressure, aerodynamic centre and neutral point. What are their functional differences?

What would be an example that distinguishes these three?


texts: Why isn't there some optional setting that can precisely move thrust levers jointly?

texts:
In the screenshots beneath (top, bottom), Capt Juergen Raps is fidgeting the A380's 4 thrust levers with his fingers to align them to the same thrust position.

Isn't it unproductive for pilots to tinker with thrust levels to align them manually?
Why can't pilots choose to bind and link all thrust levers, for moving together concurrently? If the pilot needs to move (at least) one thrust lever differently from the rest (e.g. taxiing with one option), this setting can be turned off. I'm not referring to the autothrottle.


texts: What are autothrust and manual thrust on an A320 (or other aircraft)?

texts:
The accident report on the A319 G-EUOE incident in May 2013 mentions "manual thrust", and implies that using it is very unusual.

The autothrust system failed, requiring the use of manual thrust:

  The autothrust system cannot operate  in N1 mode and so was
  unavailable for the remainder of the flight, which was  flown using
  manual thrust

But the pilot hadn't used manual thrust outside a sim session for seven years (and the co-pilot had never used it outside the sim):

  The commander informed the AAIB that, excluding simulator training, he
  had  last flown the A320-series aircraft using manual thrust seven
  years before the accident

That implies that autothrust is always used in normal operations, and manual thrust is an emergency backup only. What exactly are autothrust and manual thrust and why is using manual thrust so unusual?


texts: What would be the stall speed of Solar Impulse?

texts:
In most of the tables, only the take off (22 mph) and cruise (43) speed of the Solar Impulse are listed. It is an experimental plane, slow, with very huge wing for solar batteries.

The take off speed may not be the slowest speed the aircraft can fly, for instance, when landing. Is it possible to infer somehow the expected slowest speed of this airplane?


texts: Does a private pilot certificate require a certain number of ground school hours?

texts: To obtain a private pilot certificate in the US you need a minimum of 40 flying hours. Is there a minimum of ground school hours? Or is it just however long you need to pass the test?


texts: Why apply resolutons in data words for ARINC 429 bus

texts:
Data words transported over the ARINC 429 bus are defined and built-in units, ranges, refresh rates, number of significant bits, and resolution.

Why is it necessary to include resolution? Does resolution really have any significant impact on the signal? I think resolution is just a mere step size for the signal, so why use incremental resolutions, like 0.0000000002? Does this small incremental really make a difference in the data word?


texts: How can I create a map of all paths of flights incoming to an airport in a given day?

texts:
Is there any where I could find a map overlaid with the paths of all flights that came into a given airport on a given day?

I've found a lot of maps that show the current location of all flights, or the path of a single flight, but I haven't been able to find any that have the paths of many flights at once.

I don't really want to scan through every flight manually, but if I could see all of their paths I could pick out the ones that have interesting tangents for further study.

Background: I recently moved in to an apartment near an airport. I enjoy watching the flights come in, but one of my new roommates is less thrilled. He remarks that some of the flights seem to be pointed directly at our building until their final turn, so if the pilots were somehow incapacitated, we'd be in trouble. I think that's geometrically incorrect, but would like to prove it.


texts: Do any aircraft possess washed-in wing characteristics?

texts: I have been teaching ground school at my local Canadian Air Cadets. When I was teaching about the wing twist of an aircraft, I was asked if any aircraft possess washin characteristics (vs washout). The book teaches that wing twist is either washin or washout. Washout is supposed to decrease the wingtip's angle of attack in order to promote better stall characteristics, while washin does the opposite (worse stall characteristics). Not sure why one would want washed-in wingtips, but was wondering if anyone knew of such aircraft.


texts: What license woud an ex-military aircraft (E.g, L-39) go under according to the UK-CAA, an EASA licence or a non-EASA license?

texts:
I've been looking around for the sale of ex-military jets, to own and fly, namely an Aero Vodochody L-39 Albatros, and so out of interest had a look at the CAA website for infomation on licenses, training and general ownership etc, and across the terms EASA and non-EASA licenses, I rougly understood the meaning of them, but am unsure as to which license I would need to own and L-39.

Whilst asking this, I would be appreciative if anyone could give me some general tips and advice on owning an ex-militatry jet trainer and the kind of courses/training I'd have to undertake to own and fly it. Thank you in advance.

Please edit if I have left something important out or anything like that.


texts: Is the A330F main deck cargo compartment pressurized? If not, what is the purpose of the structural cargo access door?

texts:
I know there is a related question already asking if cargo holds in general are pressurized.

My question is specifically about the A330-243F in the below photograph. That looks like a pressure withstanding door/bulkhead dividing the fore crew compartment from the aft cargo compartment. Is that correct, and does it mean the aft cargo compartment is not pressurized? It's also possible both are pressurized and it's an airtight door for fire/fumes control.

Source

As mentioned in the linked question, it's likely both compartments are pressurized because of the efficient shape of the pressure vessel and so that the same pressurization system can be used across both passenger and cargo variants.


texts: Is this route of a airforce jet on flightradar faked?

texts:
While looking at the flight routes of Indian airforce jets on flightradar, I have noticed that the trainee jets show a very weird flight pattern. Here's an example,

The width of this screenshot is around 20KM. I don't think a jet can take such sharp turns. If so, why are these turns so sharp? Is this data somehow been faked, or is this issue with the radar?


texts: Is it legal to look for cyber vulnerabilities on a commercial airliner, in flight?

texts:
A question about hacking planes was asked here:
Is it possible to hack an airplane while it's moving (in general)?
I found it interesting that, allegedly, the flight controls and the passenger network share the same physical network.
Assuming this is true, and putting aside the fact that it would, clearly, be a poor course of action; is it illegal to probe an airliners network for vulnerabilities?
I'm also interested in what, legally, would be considered acceptable. Is scanning for devices legal?
Is attempting to communicate / connect with devices legal? Where is the line between "breaking in" and "looking through the window"?
Is there specific legislation that covers this?
Where might one draw the line between reasonable exploration and illegal activities?


texts: Under what circumstances is the Aircraft 'Stability-Axis' system used in either design or analysis of aircraft?

texts:
I understand the definition of aircraft 'Stability-Axis', but I am unsure as to the circumstances in which forces or moments would be expressed in this axis system. Is there a convention?

What I do know:

It is useful for wind tunnel analysis, where forces and moments are
often calculated from a force balance fixed to the aircraft that is
invariant with model Alpha and Yaws with the aircraft for variations in Beta. (Obviously depending on windtunnel/model set-up).
It can be used as an approximation for Wind-Axis is Alpha is known and Beta is assumed to be small.

What I don't know:

Many things
Why Stability-Axis is used instead of Body-Axis or Wind-Axis?


texts: What would be a suitable angle of attack for take off?

texts: In determining a suitable flap deflection angle for take off I am trying to come to a conclusion about the angle of attack for take off first. I have read that the highest lift to drag ratio is most desirable and for the NACA 4415 this is around 8 degrees. So I am just wondering if this would be an appropriate angle for me to carry out analysis with varying flap deflection angles with or if there is a better way to go about it. My analysis is being done on Xfoil.


texts: How do procedure designers calculate Minimum Enroute Altitudes?

texts: When the designers of instrument flight procedures design a new procedure, I understand that they use certain manuals, such as ICAO's Doc29 or FAA's  TERPS and PBN (8260.58), in order to construct each leg of the procedure by taking into consideration the required obstacle clearance. I can see how one could deduce the Minimum Obstacle Clearance Altitude from the calculated Obstacle Clearance Surface, but how do they know which altitudes, based on each leg of the designed procedure, provide adequate reception of relevant navigation facilities and ATS communications? How do they get that information?


texts: Why do we need DME or RNAV when using VOR navigation above FL240?

texts: According to FAR 91.205(e) there must be DME or RNAV system when a pilot uses VOR navigation above FL240. However, why does the regulation say we need it from FL240, not from FL180 where class A begins?


texts: In what ways do air traffic controllers communicate with pilots in class A airspace?

texts: I know they use two-way radio, but is that the only communication pilots receive from air traffic controllers? Also, in general in class A airspace, how often do pilots hear from air traffic controllers?


texts:
Is the CV-22 / MV-22 Osprey classified as a Helicopter, Plane or Both?
If the President had to hitch a ride on one, would it become Airforce One(CV-22) and Marine One(MV-22)?


texts: Why is the DC-9-80 ("MD-80") prohibited from taking off with a flap setting between 13 and 15 degrees?

texts:
A bit of digging into the 7Z9363 accident investigation has brought up some interesting information regarding the DC-9-80 ("MD-80")'s flap system:

Flaps may be positioned in any of the six permanent detents in a 0 to 40-degree range by movement of the Flap/Slat Handle. The authorized flap settings for takeoff in the MD-83 were 4, 6, 11, 15, 17, 20, and 24.73 A “Flap T.O. Sel Wheel” on the center pedestal would allow the pilot to further position the flaps from the position selected by the Flap/Slat Handle position anywhere in the 0- to 13- and 15- to 24-degree range.74 This was used to set the final takeoff flap setting, as determined
by the runway analysis review for the airport/runway.
[...]

[...]
74The Ameristar Air Cargo MD-83 COM, Limitations, page 1-24, stated “Flaps (AFM): Do not use flap settings between 13 and 15 degrees.” [Operations Group Chairman's Factual Report, NTSB docket DCA17FA076, page 32, my emphasis.]

and

4.1.3.1 Flaps
4.1.3.1.1 System Description
The aircraft has an inboard and an outboard flap on each wing. The flaps are mechanically controlled and hydraulically actuated. The crew moves the flap lever to the appropriate detent depending on the flight condition (i.e. take-off, landing). The flap lever has fixed detents at UP, 0, 11, 15, 28, and 40. The lever can also be positioned in one-degree increments for takeoff settings using the Dial-A-Flap from 0 to 24, except for a small do-not-use range at 14. Through a series of cables and pulleys, control valves are exercised and provide hydraulic pressure to the flap actuators to extend or retract the flaps. [Systems Group Chairman's Factual Report, NTSB docket DCA17FA076, page 59, section headings bolded in original, other emphasis mine.]

Reinforcing this prohibition, the DC-9-80's takeoff-flap selector wheel has a yellow "DO NOT USE" label covering the space between the 13-degree and 15-degree markings:

(Image originally by the National Transportation Safety Board [it's on page 32];1 cropped and red-ovalled by me.)
Why does the DC-9-80's flap system come with a prohibition against using flap settings between 13 and 15 degrees for takeoff?

1: The underlying photograph was taken by NTSB personnel, and the red arrow was added by the NTSB to point out the selector wheel in question.


texts: Is there a solution to radio interference?

texts:
I was reading about the Tenerife Disaster and came across what seemed to be the  probable cause behind the accident.

  A simultaneous radio call from the Pan Am crew caused mutual interference on the radio frequency, which was audible in the KLM cockpit as a three-second-long whistling sound (or heterodyne). This caused the KLM crew to miss the crucial latter portion of the tower's response. The Pan Am crew's transmission was "We're still taxiing down the runway, the Clipper 1736!". This message was also blocked by the interference and inaudible to the KLM crew. Either message, if heard in the KLM cockpit, would have alerted the crew to the situation and given them time to abort the takeoff attempt.

https://en.wikipedia.org/wiki/Tenerife_airport_disaster

I understand that the science behind radio waves is the cause for this interference, but is there a solution (non-radio if need be) for when ATC and other aircraft talk over each other?

edit1: By solution I mean a way of only allowing 1 party to speak on a specific frequency at a time , be it technical or not. I would just want the possibility of pilots/ATCs talking over each other to be close to 0.

edit2: I know the Tenerife disaster was caused primarily by the pilot's inability to wait for clearance, and then report it back, but this question is about radio interference and if a solution exists, not if fixing radio interference is a worthwhile task to begin with.


texts: Why do I get a severe headache just before landing?

texts:
I had severe painful headaches two times in my entire lifetime and both times I was in flight. I see some common factors in this two occurrences which I thought could be some known pattern so I would like to know if we can take precautions to avoid a headache.

The first time it happened to me in June 2007 while I was traveling from San Francisco to Newark. I clearly remember that I was in deep sleep and the crew member woke me up and asked me to open the blind as we were going to land soon. After opening the blind I was exposed to the sunlight and immediately I got a severe headache. It got settled just before the flight landed. I initially thought it could be due to tiredness, insufficient sleep and sudden exposure to sunlight from dark until a similar thing happened to me after 11 years.

The second time it happened to me was during my return flight last week (Jun 2018) from US to India; it was a connecting flight from Phoenix to London. Just a few (10-15) minutes before landing, the pilot started his announcement about the landing; I got this headache for a few minutes and it settled after a few minutes.

Trust me, when it happened the first time it was such a pain I never felt before in my lifetime and I got so scared that something bad is going to happen to me. The second time it was only a little better but very similar. Though I had traveled more than a couple of dozen times in between these two events, I experienced this only twice and I remember common factors in this two events

Traveling from East-West.
Moving to different timezone and at the destination it was dawning.
Pilot announcement.
Window seat.

Are there any patterns to it and can we take precautions?


texts: What is the maximum taxi speed and who defines it?

texts:
Which is the maximum speed that an airliner is limited to while taxiing?
I know that during 90 degree turns it is 10 knots, but what about long, straight taxiways? 20 knots? 25? 30?

More broadly, where I can find this information?
Would it be in company SOPs? Manufacturer's FCOM?


texts: How are the runways operated at Toronto Pearson?

texts:
I have a sort of technical question regarding the operations of runway systems at larger airports, specifically at Toronto Pearson (satellite view here). As far as I can see, the airport has 5 runways: 05, 15L/R, and 06L/R.

(Public domain via Wikimedia Commons)

Since RW05 and RW15L/R intersect it is clearly infeasible to operate RW05 at the same time as RW15L / RW15R. As for the rest, there are several ICAO guidelines regarding parallel or near-parallel runways. What do those restrictions imply regarding simultaneous operations?

Is it possible to operate RW06L and RW06R simultaneously, maybe in a segregated mode of operation? What about RW15L/R?
Similarly, can runways 15 and 06 be operated simultaneously?


texts: What hardware standards should the flight control computer pass?

texts:
There are some standards for each part of the aircraft like actuators, sensors,...
I could not find one for the flight control computer hardware. For example what are the environmental tests, or any standards for its connectors and ports,...?


texts: Does the size of control surfaces affect maneuverability, and if they are smaller, is it easier to stall?

texts: Does the size of control surfaces effect maneuverability and make it easier to stall?


texts:
Let's say we're flying the JORJO2 SID (1,2) out of KPWK (RBS transition). We are told "climb via the SID". Page 2 of the SID says "maintain 3000" but the MEA on page 1 is 4000.

Is there ever a time we are supposed to climb to the MEA?  Or are we to maintain the top altitude in the SID (3000) until specifically cleared higher?  I'm just not sure what the purpose of displaying the MEA is on this chart, lost comms maybe?


texts: Is it normal to instruct an aircraft to squawk VFR if it goes around on an IFR visual approach?

texts:
A pilot is flying IFR on a visual approach to a towered airport.  He elects to go around due to gusting winds and notifies the tower. The tower then asks his intentions. He replies that he would still like to land. The tower instructs: "Squawk VFR and enter a left downwind for runway 5."

Is the instruction to squawk VFR proper?


texts: How does the reverse thrust work while landing?

texts:
During the landing reverse thrust of an aircraft engine is seen that the compressor fan rotates in opposite direction to counter the aircraft's forward motion if I'm right So, my question here is "does the engine stops its rotation(clockwise) and than starts to rotate it in opposite direction(anti-clockwise) So, as to perform the reverse thrust operation?

In a nutshell my question is does the engine stops midair to perform the reverse thrust operation!


texts: How do pilots align the HUD with their eyeballs?

texts: In fighter jets, how do pilots align the HUD with their eyeballs?


texts:
Do wings on a plane need to be in the same plane horizontally, or can one wing root be 6" lower than the other?

The proposed application would be for a ultralight with high mount folding wings, where first 50% chord flaps would fold down 180 deg underneath the wings, reducing the "folded chord" to 50% of the full wing chord.  Then the tapered wings would scissor back about 120 deg over the fuselage and interlock like a scissor, so when the wings are folded up, they are roughly mirror the same shape as the fuselage.  One wing root would be about 6" higher than the other.

For example, with a 12" high spar root, and 3" thick wings, one 1/2 span would be mounted near the top of the spar, the other one, at the bottom on the other side of the fuselage


texts: How can a foreign pilot get renter's insurance in the USA?

texts:
I'm about to go to the United States and do some flying. I sorted out my FAA license conversion but I was wondering how to get aircraft renter's insurance. It seems that some schools / clubs require this, and it's not included in the hire contract.

I googled a bit but it's seems that all the policies are for US residents and annual contracts. I'm more interested in a month or so.

Anybody else who's had this problem? Any suggestions ?


texts: Is a clearance needed to depart a helipad in class B airspace?

texts:
I have noticed statements like the following on sectionals:

This would seem to suggest that a clearance is needed to "depart" any helipad, even if you are staying under the wedding cake. Is that true?


texts: What is this small number on the top right of an IAP?

texts:
I've looked in the instrument procedures handbook, and I cannot locate a reference for what this 5-digit number on the top right above the approach name is.

What is this number, and what does it mean?


texts:
Obviously, black boxes gather lots of media attention after tragic accidents where planes crash or explode mid-flight, since they could be crucial understanding the crash.

However, these are rather uncommon events.

Surely the black box could be used for other purposes like:

Helping the pilots understand a small mistake/hiccup/etc. on their flight
Monitor the plane's overall health
???

How often and for what purpose is black box data used?


texts: What accuracy is required in todays ADS-B position reporting?

texts:
I would like to know what accuracy is required for ADS-B position reporting.

For example, mobile phones A-GPS capable have 10 meter position error with perfect conditions.

Is this similar with ADS-B GPS receivers?


texts: Why is the maximum speed of current fighter aircraft lower than those from the 1960's and 1970's?

texts:
While reading about the characteristics of the newest fighter aircraft, I observed that their maximum speed is lower than of the aircraft in the same roles half a century ago.

For example, the iconic F-14 and Mig-25 have a higher maximum speed than their modern equivalents.

After the Cold War ended, the major air forces are only engaged in ground support and bombing against low-tech opponents who use asymmetrical warfare, and no modern scenario would see the top fighter aircraft directly engaging each other any time soon. However, for any fighter aircraft in the interceptor role, I would expect speed should be an important characteristic. Also, military aircraft are designed and introduced over a long time period, and are expected to be used for many decades.

Why did maximum speed become less important? Wouldn't it be easier to design even faster fighters now than with the technology available 50 years ago?


texts: Could flaps be raised upward to serve as spoilers / lift dumpers?

texts:
I should preface that I'm by no means an aviation person. I'm just in a aircraft knowledge obsession phase and daydreaming about designing my own ultralight (will never happen).

The idea would be to simplify and lighten a small aircraft using the flaps as spoilers. As a practical example, the same handle could be used in one movement to get from flaps raised just before touchdown to spoiler raised just after it, making it fast and intuitive.

Basically you would have on a single axis :

high lift + high drag <-> normal lift + low drag <-> low lift + high drag

Is that possible? I guess not because I couldn't find anything like that, but why?

I name them flapoilers.

The Fairey-Youngman flaps seem to do that but all I could find as explanation is "so that the aircraft could be dived vertically without needing excessive trim changes" and I'm not sure how to understand that.


texts:
Probably the question will be a little bit confusing but I'll try my best to make it clear.
Due the position of the CP with respect of the AC, symmetrical airfoils don't produce pitching moments, but cambered airfoil having the CP behind the AC produce a nose down pitching moment.
If we consider now the CG effect, a CG forward the AC will cause a nose down pitching moment, an aft CG the opposite.
Most aircraft with variable incidence tailplane have the possibility to trim much more degrees for nose up than for nose down.

Is this mainly due to the position (and range) of the CG, delianeated during the design phase and normal flight operation?
Is the pitching moment of the wing (only), much less relevant?


texts: How to reasonably determine minimum safe altitudes over city? (fixed wing)

texts:
How does one make a determination about what a minimum safe altitude is when over a city. Let's reference FAR 91.119, the two sections that talk about this:

(a) Anywhere. An altitude allowing, if a power unit fails, an
emergency landing without undue hazard to persons or property on the
surface.
(b) Over congested areas. Over any congested area of a city, town, or
settlement, or over any open air assembly of persons, an altitude of
1,000 feet above the highest obstacle within a horizontal radius of
2,000 feet of the aircraft.

"(b)" is black and white, no questions there, however "(a)" is much more subjective.
Let's say I'm over a city. For the sake of being specific, I'm not talking about downtown areas with skyscrapers, I'm referring to residential / commercial mixed areas, typical "suburbia". If the city is 15 miles in diameter and densely populated, I would think (erring on the side of caution) I would consider my glide distance when determining a MSA.
If I was directly over the center of this city, that would easily make my MSA 4,000ft AGL (using a Piper Cherokee 140 in this example). Clearly this would not be the determination most others would come to as many GA aircraft fly much lower than this over cities.
What elements come into determining an MSA in a scenario like the one I have described?

What would be considered a reasonable landing spot over a congested area?
What would be considered "undue hazard?"
What other elements come into justifying an MSA?


texts: How do the actuator loads (e.g. for the ailerons) vary between different flight phases?

texts:
Assume the hinge moment is given as

$HM = 0.5\rho v^2*C_{h\delta} \delta*S*c$

$\rho$ = air density

$v$ = air speed

$C_{h\delta}$ = Hinge moment coefficient

$S$ = Control surface area

$c$ = average surface chord

the resulting moments / actuator loads are mainly influenced by the aircraft's altitude (air density $\rho$), speed $v$ and the control surface deflections $\delta$. (AoA is neglected to keep it simple)

Can there be anything said about the actuator loads regarding different mission types or flight phases? E.g. does cruise (high altitude and speeds, small surface defelctions) cause higher actuator loads than approach (low altitude, low speed, larger surface delections).

I was planning to use X-Plane to investigate this, but as far as I know it will only output the rudder's deflections, not the hinge moment itself.

Any ideas about this?


texts: Why does the boeing 747-8 have less wing flex than the 787?

texts: If you know the 787 wing flex is much greater than the 747-8's wing why can't the 747-8 have a greater wing flex


texts: What are the exact dimensions of a B-2 Spirit?

texts:
I want to make a 3D model of a B-2 Spirit bomber. However I'd like to know the excact dimensions of it so that I can make it at least somewhat accurate.
I'd like to know the lenghts of the following red lines(each straight line separately):


texts: How do cruise missiles fly? Where does the lift come from? On pictures you can see that they have wings what are tiny compared to the body / payload. Do they generate enough lift? Or is the propulsion, other than in most aircrafts, not just used to overcome drag but also to generate lift, i.e. the thrust force is angled down?


texts: Does ducted fan require more engine torque than unducted-fan,at same RPM?

texts:
Two identical fans, one is unducted and other is ducted,both operate at same RPM.
•Does ducted fan require more engine torque than  unducted-fan ,measured both at same fan RPM?
power=torque x RPM so in my case more torque mean same as more power("induced power")...
(Engine torque is direct indicator which fan has higher  drag at blades.We can make analogy with wall to wall airfoil(represent ducted fan) vs 3D wing (no side walls at wingtips )represent unducted fan.
Here is problem:
I think ducted fan requier more torque for same RPM(maybe I am wrong?),which means it has higher drag than unducted fan,but in theory wall to wall airfoil must has lower drag than 3D wing at same speed and same AoA.
•How explain this contradiction?


texts: Where can the latest maps marking all dangerous areas be found?

texts: I'd like to be aware of and include areas (in the requested maps) that might not be prohibited, but discriminated, mentioned, singularised, or warned in any way. An example: http://www.newrepublic.com/article/118764/map-faa-tells-airlines-avoid-flying-over-these-countries


texts: How dangerous can it be if something falls from a flying aircraft?


texts: What safety precautions are taken for an airline prototype test flight?

texts:
Regarding the software, the equipment and the personnel.
Can the crew jump out of the plane with parachutes or is it a bad idea?
Additionally, if you would compare the safety of today and the 1970/80s what would be the difference?
Thanks in advance.


texts: How do I use the "Inoperative Components or Visual Aids Table" when more than one component is inop?

texts:
I can't fully seem to understand this sentence:

  If more than one component is inoperative, each minimum is raised to the highest minimum required by any single component that is inoperative

Can someone please explain this for me? Perhaps using a scenario with an approach where some equipment is inoperative?


texts:
I use https://flightplanning.navcanada.ca to get METARs and TAFs for my local stations. While listening to CYPK tower at work I noticed something in the header of my VLC:

That's a METAR! But why doesn't it show up at NAV CANADA?

That got me wondering where those reports/forecasts actually come from. After the station observes weather, does it report it to a central service? Does the station itself predict the future conditions to create the TAF?


texts: Determining total engine life in relation to SMOH/SFOH

texts:
When evaluating the value of an aircraft, the total hours since major (or factory) overhaul (SFOH/SMOH) is an important indicator of price since it tells us how many hours the engine has operated since the last overhaul.

I read in another answer that the typical time between overhaul (TBO) interval for a piston engine is 2000 hours.

However, what is the best way to determine the actual TBO interval for a given engine model? I'm hoping someone might know of a handy list somewhere rather than having to dredge through service manuals for each model I'm interested in.


texts: To what extent can I deviate from the endorsement guidance given in AC 61-65?

texts:
Specific case:  I have a student who is ready for his ride, but he has not yet scheduled it, and because I'm moving, I will be permanently unavailable to endorse it in a few days.  I want to add a stipulation to his endorsement that says the endorsement is valid only until a certain date, and it's only valid if he has had some number of hours of flight training within the preceding $x$ days.

Neither of these items are mentioned in AC 61-65.

General case:  How much can I legally deviate from the guidance for checkride endorsements given in AC 61-65?


texts: Where does the term 'greased landing' come from?

texts: I've heard this term used a few times to describe a really smooth landing (one where you hardly feel a bump).  But where does this term actually come from?  I'm not sure how grease (a lubricant) came to symbolize a low g-load on landing?


texts: Why would a VOR be decommissioned leaving the DME?

texts: As can be seen on this question and this question the OJC VOR has been decommissioned but the DME is still active. What would be the purpose in having DME without VOR?


texts: Why are many military fighter aircraft designed to fly supersonic?

texts: It is my understanding that these aircraft rarely fly at supersonic speeds anyway—the ordnance they carry, the increased fuel burn (even with supercruise), and the increased chance of detection make supersonic flight either hard to maintain or seem unnecessary. In addition, it would seem more beneficial to perform subsonic evasive maneuvers against an incoming missile than to try to outrun it (many air-to-air missiles fly at Mach 3 or higher). Finally, the subsonic Sea Harrier even downed a supersonic-capable Mirage III and many supersonic-capable IAI Daggers to no losses during the Falklands War. Though this can be attributed to the superior pilot training and offensive technology of the Harriers, how come many other aircraft were/are produced with a supersonic requirement?


texts: How hot would pressurized air get if the air conditioning failed?

texts:
I understand that aircraft are pressurized by pushing air into the cabin using the engines, and using a valve to let the air escape at a controllable rate thus achieving the desired pressure differential. However, when air is compressed, it heats up and if I understand correctly, all pressurized aircraft have air conditioning units to keep the temperatures at a reasonable level.

If all air conditioning units were to fail, how hot would the air being shoved into the cabin actually be? If this depends on aircraft and or engine type, any example as a ballpark figure would be appreciated.


texts: Why isn't there a single start button for all systems on aircraft?

texts:
Why is it that airliners and aircraft do not have a single start button for all systems?

On TV etc., I noticed that pilots pressing buttons above and below forward and sideways, mostly above though, switching on button after button, switch after Switch.

Why not:

have single start button for all systems where a computer does all the check lists?
is because they need to do checklists hence the switches?


texts: Could you help to identify this WW1 fighter?

texts: Please help me identify this world war 1 fighter.


texts: How accurate must fuel gauges be for VFR flight?

texts:
All Private Pilots should know the acronym TOMATO FLAMES for the Minimum Equipment List (MEL).

On that list, F means Fuel Gauges.But what exactly is required of fuel gauges?

Yesterday, my rental plane came with a note that the fuel gauges were swinging wildly, and bouncing to zero occasionally.   I planned a 90 minute flight, starting with full fuel, so there was no real risk of running out of gas.I decided the fuel gauges probably didn't meet the spirit of TOMATO FLAMES, but I admit that I don't know what the exact requirement is.

How accurately do the gauges have to work to be legal?


texts:
London has six international airports: Heathrow, City, Luton, Southend, Stansted, and Gatwick. It might even have eight international airports if you count Birmingham Airport and Southampton Airport.

Why does London need so many? I think two airports is enough. Plus, they are put in bad locations. So, is this for a practical, or some kind of other reason?


texts:
Are there polar plots and airfoil data points available for the RAF4?

I understand this is the airfoil used for the horizontal stabilizer of the Zenith 701, which should be similar to a NACA4412 airfoil.


texts: Why do military pilots report "gear down" during their traffic calls?

texts:
I've noticed that military pilots will often say something along the lines of:

  <airport> traffic, Basher 5-2 left base, full stop, gear down.

Why the additional "gear down" call?  Shouldn't it be implied that if you're landing full stop, you'd want the gear down?  And similarly, if the gear isn't down, wouldn't an emergency call be more appropriate?

To be clear, I'm not asking why it's a good idea to check to see if the gear is down, I'm asking why military pilots broadcast the fact that they've checked.


texts: How is the centre of lift estimated for airplane models before they are being mounted in a wind tunnel?

texts:
They mount the airplane models or parts of an airplane like just a wing, or a rudder in wind tunnels to test their drag and lift, stability, etc.

How do they know where to hang it from or mount it on. How do they estimate the lift center of a new design of a jetliner which has no predecessor to use as a reference.

I am guessing it is a process of trial and error. But there must be an algorithm or method to arrive from an estimate to actual lift center.


texts: How much do the wings weigh?  How much does the landing gear weigh? How much fuel does it take to fill the tanks? We, at Confederation College are trying to donate a DC-9 for training purposes and require information to facilitate this.


texts:
I was the safety officer at a glider operation earlier this year and we had a new tow pilot who forgot to drop the rope. By radio, I instructed him to drop the rope before landing. The downsides of this is that it would temporarily leave the rope in the middle of the grass field where an aircraft might run over it, and also someone would have to golf cart out to retrieve the rope.

Later, when he found out about it, the chief tow pilot got angry about this and said the tow plane should have landed with the rope attached and dragged it back to the launch location. I thought this was unwise because this could damage the rope, or if the rope were to catch on something as the plane landed, it could have dangerous consequences for the tow pilot. Also, I have seen loose tow ropes whip around. Considering that there is a metal buckle at the end of the rope, imagine that thing whipping around. If the plane landed with the rope attached, I was picturing that buckle whipping into a bystander or a parked plane.

Of course, the third possibility is that he could do a go around, fly all the back and do the rope drop correctly. The disadvantage of this is that it would delay the return of the tow plane for another 10 minutes while he did the go around, and we had multiple people waiting for tows.

What is the best procedure?


texts: I have been making the mistake of using words "propeller" and "rotor" interchangeably when they are not the same thing. What is the difference between a propeller and a rotor?


texts: Do you get separate certificates for CFI and CFII?

texts: I passed my CFII checkride the same month my CFI was to expire. So far I have only received a new CFI card in the mail. Shouldn’t I be receiving a card that says CFII on it as well, or should the card I received have read CFII? Are there two separate cards?


texts: What is the benefit of having baro-VNAV in addition to a WAAS GPS?

texts: On Cirrus' 2015 aircraft page, they advertise Baro-VNAV capability in the new model. Having never done an LNAV/VNAV GPS approach (only LNAV or LPV), I'm wondering: when would I actually use it, if I already have WAAS and can just use the LPV approach? Typically, I'm used to seeing an LPV minima alongside any LNAV/VNAV minima. Are there exceptions? Is this feature valuable in practice?


texts: Can a US pilot fly a German D-xxxx aircraft in Germany?

texts: Can a pilot with a US FAA certificate and a proper rating legally fly a D-xxx German-registered aircraft within Germany? How about the rest of the EU? Does it matter which type of aircraft? I'm most interested in gliders, but the question is more general.


texts: What's the greatest height at which a bird has collided with an aircraft?

texts: 70% of birds fly below 1,500ft, 25% of birds fly between 1,500ft and 15,000ft, and only 5% above 15,000ft. What is the greatest height at which a bird has hit an aircraft? What species was the bird?


texts: In order to become a pilot, should an individual have an above average mathematical ability?

texts: I would very much like to become an airline pilot however maths has never been my strongest subject. Are most pilots mathematically adept or can I get away with being average?


texts: When should an Obstacle Departure Procedure (ODP) be used?

texts:
Buried away in the front matter of the FAA charts is a section titled "IFR TAKEOFF MINIMUMS AND (OBSTACLE) DEPARTURE PROCEDURES".  Note that this is not a graphical departure procedure that is in with the rest of the approach plates.

Knoxville, TN (KTYS) contains the following departure procedure in that section:

  DEPARTURE PROCEDURE: Rwy 5L, climb heading 048°  to 3400 before
  proceeding on course. Rwy 5R, climb  heading 048° to 3500 before
  proceeding on course. Rwy  23L, climb heading 228° to 3500 before
  proceeding on  course. Rwy 23R, climb heading 228° to 3500 before
  proceeding on course.

Question: If I receive an IFR clearance along the lines of "*N1234, cleared to XXX as filed, climb and maintain...." and I didn't file any kind of departure, am I expected to fly the above ODP, and will ATC know what I'm doing if I do?  Does it matter if it is VMC or IMC?


texts: When outbound from an IAF on an approach to a procedure turn, may the pilot choose whether to use time or distance?

texts:
I was trained that if a fix to be flown over and then outbound for an approach is off-airport, then fly out for 1 minute prior to making a procedure turn.  If it is over the airport, then fly outbound for 2 minutes instead of 1.

Would it also be proper to simply decide on a minimum distance to be flown such as 5NM outbound from the fix as long as it is within the published maneuvering area for the procedure such as 10NM from the IAF?

I know the times are only guidelines, but basically, what I am asking is would not using time at all and simply using DME as the guide be considered improper procedure?

Here is an exemplary approach to add something tangible to this question. It has an off-airport procedure turn with a requirement to remain within 10NM.


texts: How safe is the Certified Rotax 912 versus the Continental O-200?

texts: I'm thinking of buying a taildragger LSA, many of which have a Rotax engine. Continental and Lycoming are the major suppliers of certified piston aircraft engines, and they are considered to be safe engines (for pistons!). I'm wondering if I should consider the safety and reliability of the certified Rotax engine to be substantially worse than that of the Conti O-200 (the only other certified LSA engine), and if there is any evidence one way or the other.


texts: Which precautions should I take when flying in very cold / hot weather?

texts: What are the important precautionary measures to take when a flight (either GA or airliners) is operating in extremely cold (e.g. -10°C or below) or extremely hot (e.g. 40°C or above) weather conditions?


texts: How does engine noise change during descent / approach?

texts: When on the ground beneath a STAR transition I hear commercial jets making a dramatic change in sound. I assumed it was the sound of high-bypass engines being pulled back at stepdown fixes, but when a friend recently asked me what the sound was, I wanted to make sure I was providing the correct answer. I am familiar with the sound made by the Fuel Over Pressure Protector (FOPP) cavity on A380s but this is a different, much lower pitched and shorter duration sound. Any help?


texts: Why are test crashes not made harder on the airframe?

texts: This is one of the videos of the crash: 727 Test Crash. It seems it was more of a hard landing without gears. Why wouldn't the experimenters have made it more of a really hard crash if they needed to study the effects of a crash on a plane? Would slamming down the plane really hard (maybe even nose down) given a more realistic scenario and more valuable data rather than making it soft?


texts: What are the weights of vertical and horizontal stabilisers of a Boeing 747-400?

texts: For my math exploration (IB) I am doing something related to aircraft. So I was wondering what the weights of the horizontal and vertical stabilisers were. If you do know the weights please state the source of the information too.


texts: Is 1 propeller always more efficient than 2?

texts:
Based on other answers I've read here (1) (2) (3), a single large blade propeller is the most efficient type of thrust you can get.

There are 2 reasons for this (as I understand it). Firstly, because each blade on the propeller causes wing-tip vortices when low pressure air meets high pressure air.

Secondly, each blade on the propeller adds surface area to the aircraft increasing parasitic drag.

So my question is what if both propellers are surrounded by a duct? Assuming it's a perfect fit, the duct will neutralize wing-tip vortices, so now all that's left is parasitic drag.

Now couldn't you just use 2 propellers that equal the surface area of a single large propeller and get the same efficiency with no added parasitic drag?

On a similar note, could you use just 1 small propeller surrounded by a duct and reach similar efficiency (if not better) than a large propeller surrounded by the same duct?

I say "if not better" because the smaller propeller would have less surface area, thus less parasitic drag.


texts: It could be a Learjet, but I can't find a match.


texts: How have deep-seated cultural human factors (particularly in east Asia) in the cockpit been successfully managed in the past 20 years?

texts:
This question is based on https://aviation.stackexchange.com/questions/27814/ and related to:

How does cultural difference impinge upon human factors in aviation industry safety?
To what extent have political (race, gender, social class) attitudes been implicated as human factors in the cockpit?

Successful management of cultural human factors

East Asian airlines used to have poor safety records, notably KAL and Chinese airlines, in part because of cultural human factors in the cockpit (hence the disquiet in Korea over the notorious nut rage incident in 2014).

The last two decades have seen considerable improvements in these safety records.

To the extent that the improvements have been related to better management of human factors (rather than say better technical resources and practices) what approaches have been successful in managing these cultural factors to improve safety (and to what extent)?


texts: How can I politely remind ATC that I'm waiting for instructions or clearance?

texts:
(background: low-hour, low-experience, private pilot.)

I've got an issue regarding talking to air traffic controllers, especially when I think they may have messed up, yet still giving them the respect they deserve as hard working professionals.

One common scenario is when I'm ready to go, along with multiple other planes, all coming from various taxiways.   I know the tower tries hard to clear us each more-or-less in the order we've called up.   But when one plane feels they've been badly skipped, or possibly forgotten, it can get awkward.

I've heard a pilot say (very politely, and with good cause):

  "Tower; Arrow-23: Did you forget about me?"

only to have the tower come back with a snappy and frustrated:

  "I'm doing the best I can.  I'll get you all out of here as fast as I can.  Just wait your turn!"

Obviously, that didn't go very well.

On the other hand, I've tried to be patient for awhile, only to learn that the Tower really did overlook me, and sequenced several planes out in front of me.

On the ground, its wasted fuel, HOBBS, and time.
But in the air, it can be more significant.

Sometimes I've had tower miss actually clearing me to land.If they're trying to sequence me in, I stay on an extended the downwind leg for a long time, waiting to be cleared before turning base.  But if they really did get busy and overlook me, I can end up well out of position.

If I call and ask, sometimes they'll get a little testy with me if they are just busy.
If I stay silent, I might've been skipped/forgotten, and end up flying downwind for a long time.

Whats the most appropriate, friendly, and polite way to check in and make sure nothing got missed, without sounding accusatory?


texts: What makes it safe for the DC-8 to use reverse thrust in flight?

texts:
For most jets, the use of reverse thrust to slow down in flight, where even possible, is extremely dangerous, and strictly prohibited.

Not so on the DC-8, which is certified for the safe in-flight use of reverse thrust on the two inboard engines throughout its entire flight envelope, and which, in fact, uses in-flight reversing as a standard part of a normal descent - this despite the severe disruption in-flight reversing causes to the airflow over the wing.

What is it about the DC-8 that makes it capable of safely using reverse thrust in flight, unlike other jets?


texts: Are there any aircraft used in part 121 (aka scheduled airline) operations that do not require a type rating to fly?

texts: Inspired by KeithS's question about ATPLs and category/class ratings, I figured I'd throw another type-rating/airline-operations puzzler at you: are there any aircraft currently in scheduled airline service (i.e. operated under part 121) which would not require a type rating to fly?  (I know part 135 operators often fly small aircraft due to the nature of their operation, with more intermittent or even on-demand service and the smaller locales they fly into.)


texts: Are there any publically available recordings of conversations between ATC and pilots?

texts:
It can be either audio or transcription.
It would be perfect if it also contains aircraft tracks.


texts: Do small business jets have HEPA filters?

texts: Do small business jets (Phenom 300 for example) have HEPA filters for recirculated air? Or don't they recirculate air at all?


texts: Is a horizontal stabilizer necessary on an aircraft with a tandem wing?

texts: Let's say that there is an aircraft with more than one main wing and each of these wings have elevators. Would it be necessary to have a horizontal stabilizer? The figure below shows an example of what I'm thinking.


texts: Why is TO/GA button disabled in 777 with weight on wheels or below 2 ft RA?

texts:
Recently a final report for accident of an Emirates B777-300 at Dubai on 3rd August 2016 was published. An important factor there was that when the pilot tried to recover from long landing by going around, the TO/GA buttons were inhibited because the wheels were on the ground and the pilots did not realize this.

Now at first sight, this seems like an unnecessary complication of the auto-thrust system that just adds a point the pilots need to learn. But I suppose the engineers did have some reason to add this bit of logic.

So what dangerous condition is inhibiting the TO/GA button when weight on wheels or radio altitude below 2 feet for 3 seconds supposed to prevent?

I would understand after reversers deployed, but before that going around is considered appropriate solution for long landings and bounces, both of which might trigger the inhibition.


texts: In an Airbus, if the AOA sensor fails and the computer pitches the plane down, can the computer still only pitch down 10 degrees maximum?

texts:
For example, something similar to Qantas Flight 72.

Assuming the Angle of Attack sensors are faulty and give bogus data - for example, that the Angle of Attack is 20 degrees, or the maximum Angle of Attack when the plane is flying normally and in no danger of stalling.

The flight protection systems are going to kick in and try and pitch the plane down because the computers will think the plane is stalling or about to stall because of the (bogus) Angle of Attack readings.

Would the computer still be restricted in how far it can pitch the nose down? For example would it suddenly angle down but stop at 10 degrees nose down, or would it go into a ballistic, unrestricted and dangerously steep dive?

I read a pilot in an Airbus cannot make the plane pitch down more than 10 or so degrees in ''Normal Law'', would this apply if the plane's computers are trying to pitch the plane down due to faulty AOA sensor data?


texts:
I was reading an article about TAM Airlines Flight 3054 crash and I saw the following:

METAR

  SBSP 172200z 35008kt 7000 -ra Bkn008 Ovc070 15/14 Q1018
  SBSP 172200z 35008kt 7000 -ra Bkn008 Ovc070 15/14 Q1018
  SBSP 172100z 34008kt 6000 -ra Bkn009 Ovc070 16/14 Q1018
  SBSP 172030z 32009kt 7000 -ra Bkn013 Ovc080 16/14 Q1018
  SBSP 172000z 31012kt 8000 -ra Bkn016 Ovc080 17/14 Q1018
  SBSP 171900z 34009kt 9999 -ra Bkn016 Bkn080 18/15 Q1017

Questions:

What is METAR?
How is it read?
What is the difference between the International METAR codes and the
North American METAR codes?


texts: The FARs "require" the wearing of parachutes for certain types of maneuvers. Is parachute training required?

texts:
FAR 91.307 (c)  requires that each occupant of an aircraft must wear an approved parachute during the execution of certain types of maneuvers (e.g., more than 60 degrees of bank or
or 30 degrees pitch, etc.).  Is there a legal requirement that those occupants have any specific training in parachute operations or jumping?


texts: What the preparations and procedures to consider for circumnavigation?

texts: If one wants to circumnavigate the planet in a general aviation airplane, how can one do it and what are the important issues to consider?


texts:
I'm wondering about the type of jet in this lego kit:
https://shop.lego.com/en-US/Airport-Air-Show-60103

One of the jets appears to be an F-18 (the one with twin tails, of course) but I can't place the other one. It looks vaguely like a Eurofighter, except this model only has a single engine.
I realize that these are stylized models, but I was hoping someone could at least identify what they are "based" on.
Thanks!


texts: How can pilots obtain runway length information for airports that do not appear in the chart supplement?

texts: How can pilots obtain official runway length information for airports that do not appear in the chart supplement such as private airports?


texts: How well can an airplane which is tied down be protected from a blizzard?

texts:
I've been in the very early stages of shopping for my first single engine plane. That has made me more thoughtful about the environment in which a given plane is stored. So the recent blizzard in the Northeast has had me asking some "what-ifs" from a perspective buyer's point of view.

In the Boston area, there are forecasts for 15-25 inches of snow. If a typical GA plane (e.g. a C172) is tied down in those conditions, is the weight of that much snow on the wings sufficient to cause any permanent deformation or other issues? Are there things you would instruct your pre-buy inspector to pay extra close attention to knowing the plane had been through such an extreme event?


texts: Detection of solar balloons by ATC primary surveillance radar

texts:
I am curious whether a 30 cubic meter solar balloon made of black nylon and filled with ambient air would be detectable by the primary radar used by ATC in Continental Europe. Due to its size and light weight, a balloon of this kind is not required to carry a transponder to fly in European airspace. I wonder, given contemporary target-detection filters in primary radar relative to background 'clutter' or noise, whether an aerostat of this kind would be detectable.
Thank in advance,
Sasha


texts: Why does the zeppelin NT tail use 3 fins?

texts:
I don't if I use the correct vocabulary. By "fin", I mean the control surface at the tail of the airship. As a control surface, it contains a moving part.

As airship used to have at least 4 fins at the tail: an elevator (1 fin on the right side, another one the left side) and a rudder (one fin on the bottom and one on the top, I highly suspect both are useful to be sure at least one is in undisturbed airflow while cruising at any positive or negative angle of attack). This seems reasonable to ensure both redundancy and simplicity (not mixing pitch and yaw controls). Yet, aircraft with V-tail prove that we can reduce the number of mobile control surfaces located on the tail, but it does not seems to be reasonnable in all cases.

For the Zeppelin NT, only 3 fins are used. I clearly imagine the vertical one is used for yaw control only. The 2 others are shaped as an inverted V, thus I imagine they mix both yaw and pitch control as V-tail does.

What is the rational behind the choice of number of control surfaces? Why do the Zeppelin NT uses 3 of them?

Wikipedia provides few reasons I fail to understand:

it states less fins allow weight gains. for me, less fins implies bigger fins to provide the same authority, thus mitigating this point
it states the loss of one fin can be compensated by the 2 other. For me, the loss of one fin would provide a rolling moment when trying to compensate, and there is no other surfaces to mitigate it (on an aircraft, coupling is possible because it has wings)


texts: When an aircraft is descending, does any lift act on it? If yes, how?

texts: When descending , an aircraft never goes in free fall, even if negative angle of attack is large. Does that mean the net downward force is not gravity, but less than gravity, due to certain lift acting at all negative angle of attacks?


texts:
During the Concorde's takeoff run, this piece of debris still lying on the runway, was run over, cutting a tyre and rupturing it.  A runway inspection, scheduled for 15h, had not been carried out.

How is a runway inspection carried out? How often is a runway inspection done? And, what all is checked in a runway inspection?


texts: What prevents fighters from being fitted with jetliner-style bleed-air wing anti-ice?

texts:
In a comment, John K points out that:

In any case, military fighter aircraft have to avoid icing, which is kind of odd for those that are considered "all-weather" interceptors..

This, to me, raises the question of "why would you omit wing anti-ice from a supposedly 'all-weather' aircraft?"  Especially on a larger fighter like a F-15 or Su-27, it seems to me that the weight penalty for a couple of piccolo tubes, two butterfly valves, and a bit of extra bleed ductwork would be fairly minimal relative to the weight of the aircraft and payload, or am I wrong on that?  Or are there aerodynamic or engine-performance reasons that prohibit fighter jets from using bleed-air anti-icing, or some other anti-ice system for that matter?  I've also heard the saw that "fighters don't need anti-ice because they can simply fly fast enough to use ram rise to deal with icing", but could there be other reasons they couldn't fly in icing, such as not having heated pitot/static systems or inlet anti-ice functions?


texts: How long should a boarding pass be preserved, after the trip? Is there any FAA mandate on the same to make any claims later?

texts:
Ok, i'm not sure if this is relevant to AviationSE, but my query is as a passenger.

How long should a passenger preserve their boarding pass after their trip? This is with view for making any kind of claim on the Airline, be it for lost luggage, or injury during the trip, or any thing else. Is there any relevant FAA guideline or rule on the same?


texts: How can pilot remember when or where to do tasks such as changing radio frequency and change fuel tank?

texts:
As a student pilot, I sometime forget tasks such as changing radio frequency after reaching a location or switching fuel tank in long navigation.

  These tasks happen in specific time or location and may not be in checklists

Is it something experience will help or
Are there method that can help pilot remember these tasks?


texts: What is the ceiling to prohibited space P-47 (or any other P-zone)?

texts:
On the Dallas-Fort Worth sectional, notice one of the few permanently Prohibited airspace zones west of the Mississippi; P-47, around the PanTex nuclear plant in Amarillo, just northwest of Husband Intl (AMA) and within the outer cylinder of its Class C space.

Now, that zone is directly in the path of AMA's longer runway, 4/22, and Victor routes including V12-280 extend directly away from the PNH VORTAC at AMA right over the top of it.

That leads me to think that either P-47 has a ceiling above which airliners are allowed to operate, or else AMA Approach and Fort Worth Center via Amarillo RCO have a dickens of a time routing incoming traffic when the winds indicate use of runway 4/22. The outer Charlie cylinder begins at 4800 feet, but the chart also clearly states that P-47 is excluded from AMA's class C space where they overlap. That leads me to think that this P-space extends to Jupiter, and all flight traffic including AMA arrivals/departures (it's not a big town, but it's not exactly BFE either in part because of Pantex) have to maneuver specifically to avoid P-47.

So, to confirm, is there any altitude at which you can overfly P-47, or in more general terms any P-zone?

It seems kind of silly for many P-zones, including this one, to extend all the way to space, as beyond a certain altitude if nothing else it becomes impractical to dive straight down into the facility under protection. But, if that's the law...


texts: How does fuel efficiency depend on wing configuration?

texts: Which of the following wing configurations is the most fuel-efficient?


texts: How does a constant-speed propeller work?

texts: My explanation of how a constant speed propeller works has always been a little shaky. I know about the "speeder spring," "counter-weights," and how it utilizes the engine oil pressure, but I'd love to know of a simple and easy-to-understand diagram and explanation that I can use to really understand it, and then teach it to others?


texts: Is it a mistake or standard procedure to lit the landing lights only on very short final?

texts:
Yesterday I was spotting at Barcelona International (LEBL). I noticed that at least two airliners were approaching with their landing lights OFF, just to light them on very short final (about 0.4NM from runway threshold).

I thought landing lights were required to be ON at all times below 10000 feet. Am I wrong? Is there any situation when landing lights are not required below 10000 feet?

Visibility was excellent, I'm going to see if I can find the actual METARs but I would say CAVOK conditions. see the METARs:

LEBL 161630Z 17007KT 140V210 CAVOK 19/11 Q1019 NOSIG
LEBL 161700Z 20007KT 150V230 CAVOK 19/11 Q1019 NOSIG
LEBL 161730Z 22007KT 170V240 CAVOK 19/12 Q1019 NOSIG
LEBL 161800Z 21007KT CAVOK 18/12 Q1019 NOSIG
LEBL 161830Z 20005KT 170V230 CAVOK 18/12 Q1020 NOSIG
LEBL 161900Z 21005KT CAVOK 17/12 Q1020 NOSIG


texts: Why do the Comet's engines point outwards?

texts:
As it's visible from the images below,
when looking at the plane from the top, the engines point outwards and they are banana-shaped, why is that?

(unfortunately I couldn't find a real photo straight from the back of the airplane, from that angle it is way more noticeable),

https://upload.wikimedia.org/wikipedia/commons/9/93/De_Havilland_Comet.svg


texts: What's the pattern of airflow over the airfoil at high angle of attack?

texts:
When at high angle of attack the boundary layer tends to:
A. stagnate and stop
B. loop around the upper camber line
C. decrease air pressure along the chord

The answer is A, but as I see it, B seems like a better answer. What's your opinions?
For your information, the material explains that B is the wrong answer because "As the boundary layer becomes stagnate and stops, the airflow will separate and loop around the upper surface and a stall occurs," which I don't find satisfying.


texts: How do airlines train their pilots to deal with the stress of delays?

texts:
There are some good answers here dealing with boredom during long flights and with the physical stress of piloting, and with what pilots to do during a delay. I'm interested in how pilots cope with the mental stress of delays.

Consider - you're flying home, you've been sitting on the tarmac for three hours with no idea of when you're going to be cleared to take off, and your child has a birthday party you really want to make. Another five minutes and you're going to have head back to the terminal because of the mandatory rest period; the tower starts to give clearance to the planes in front of you but they seem to be taking an interminable time to complete their checklists.

These are the sort of things you face as a passenger; luckily for most of us they're pretty infrequent.

For a pilot, however, they must be quite regular, especially on certain routes. And the added complication is that the temptation to rush or cut corners could lead to disaster.

Do airlines have specific training on how to cope with the stress caused by  situations where they will find themselves under time-sensitive / delay pressures?

Robert Hays under pressure in Airplane!


texts:
Flight AWE685 goes from Seattle to Philadelphia.

What exactly is that AWE685 identifier called?  Every flight seems to have a unique name.  I'm trying to learn more about flight data but it's tough when you don't know what terms to Google for more in-depth results.

Apologies if this question doesn't have a simple answer.  I'm trying to learn about HTTP requests, so I'm teaching myself by pulling flight data from websites.  Also, aviation data is new to me, so I don't realize how easy/difficult of a question this is.


texts: How can an airline flight crew handle an in-flight oxygen system fire?

texts:
The first step in the "Smoke, Fire, or Fumes" checklist for any pressurized aircraft is for the crew to put on their oxygen masks and set them to EMERGENCY, so that the crew can breathe, and thus function well enough to execute the rest of the checklist.

However, it's possible on at least some aircraft for a fire to develop that intimately involves the flight crew supplemental oxygen system, as the hull loss of SU-GBP aka EgyptAir flight 667 at its gate in Cairo Int'l demonstrated dramatically.  Fortunately for the EgyptAir crew, their experience happened with the aircraft squarely on terra firma, allowing a swift evacuation with only a few serious injuries.  However, if a similar event happened while cruising over the ocean at 35,000', what could the flight crew do to avoid being incapacitated, considering that such a fire would render at least part of the crew oxygen system inoperable?


texts: What was the value proposition of the 767-400ER over the 777?

texts:
Aside from visible differences, what are some differences in the usage and design of the 767-400ER as compared to the 777-200/200ER (or 300/ER if you feel makes more sense)?

What was the value proposition of the 767-400ER when compared to the 777, as both came into service within a decade of each other?


texts: What's the advantage of the F4U Corsair's gull wing design?

texts:
What is the advantage of the F4U Corsair's gull wing design?

Is there also a disadvantage to this? The wing design just seems odd, and as far as I know it is one of the only planes to use this design.

Is this because the technology advanced so fast, or because the wing design was flawed?


texts: What effect does downwash have on the horizontal stabilizer

texts: Fighter aircrafts usually have their horizontal stabilizers in lined with the main wing which would subject it to downwash. How does this effect the stability of the aircrafts and the effectiveness of the elevator?


texts: What is the purpose of using 8.33 kHz instead of 25 kHz frequency spacing?


texts: Why does the autopilot disengage even when it does not receive pilot input?

texts:
After having read the disturbing

https://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash

I'm left with the question as to why the computer allows for the autopilot to be disengaged when there is no pilot input.

Why doesn't it engage the stick shaker and alarm as normal, but maintain control until pilot input is received, or require the pilot to manually disengage the autopilot?

I'm not a pilot, so I'm sure there is good reasoning behind this. However, from my own naive perspective this is why it seems foolish to automatically disengage the autopilot:

This is what happened after the autopilot was disengaged:

"The target is descending and he is doing multiple aileron rolls, looks like he's out of control...in a severe descent, request an emergency descent to follow target."

Imagine that the crew did regain consciousness, they would find themselves in a disorienting situation, with an aircraft possibly damaged from aerodynamic stress when approaching mach 1 in an uncontrolled nose dive. This, compared to the autopilot simply maintaining attitude as best it can.

Until finally, this: "the aircraft hitting the ground at a nearly supersonic speed and an extreme angle."

The alternative being, with no pilot input that the aircraft would have maintained a somewhat stable attitude, deploys its landing gear, flaps, and prayed for the best -- that there just happens to be a fairly smooth piece of land, with no major obstacles in the way?

Now, I'm aware that all six on board were dead before the plane crashed. That doesn't mean there are no situations where a controlled crash landing is not preferable to an uncontrolled crash.

I'm not an avionics software engineer, so forgive me if I don't appreciate the complexity of the task -- but as a software engineer and someone with an IT education it seems to me almost trivial to extend the functionality for the aircraft to accommodate for this scenario with a mostly hard-coded procedure---yes, blindly landing at whatever is there and hoping (and with the system being extended with visual processing, perhaps, in the future). While I'm not even going to sketch a full proposal for such an extension here, it is part of my motivation for asking this question in the first place, so I'm simply mentioning it as that.

I can also mention, although I'm sure anyone qualified to answer this question will know about this case (and know it far better than I do), the Cornfield Bomber https://en.wikipedia.org/wiki/Cornfield_Bomber so if this is possible without any help from the computer, surely it would be possible with help, even from a computer that only has basic instruments (altitude, attitude, etc.) and no vision, yet simply attempts it "blindly" as far as visual processing is concerned.

Please keep in mind that I'm under no illusion that the plane will land without a scratch. This is a game of statistics, such as all safety procedures, and it seems (naively, I'm sure) that this might increase the chances of survival by some (probably slim) margin.

My own attempt at an answer:

I can only imagine that the reason such functionality doesn't exist, is because it is so rarely useful and considered too much of a curiosity. However, other crashes that also appear to be highly unlikely in general, have seen changes enforced in the aviation industry. So this isn't really a good answer.

The only other thing I can think of, is the omnipresent fear of AI. The idea to implement some AI, that could potentially, when given full authority of the plane, glide it into a building unintentionally, is just unthinkable for obvious reasons. While I sympathize with this view, I don't see why this is more likely than it happening with a plane flying without such a simple AI---both the AI and the completely uncontrolled plane would be flying just as blindly, both at risk of hurting innocent bystanders. The only difference is that the AI assisted plane flying autonomously (despite mostly blindfolded) does have a marginally higher chance of allowing for some survivors.


texts: How reliable are aircraft cutaway drawings from Flightglobal?

texts:
I am working on a new system that would be retrofitted on jets (can't talk much about it yet), and I was looking for detailed drawings to start creating its detailed engineering design.

I stumbled upon this website, does any of you know how reliable Flightglobal and those drawings are / where they get their information? Your opinion would help a lot.

Thanks!


texts:
Were any biplane flying wings built and flown after the 1912-1914 variants of the Dunne D.8? If not, why?

Wikipedia mentions merely that this type was too stable and insufficiently controllable, but that's not inherent to this layout.  And the biplane's stiff truss structure remained useful for the next half decade.


texts: How are type ratings created for new aircraft types?

texts: When a new aircraft is developed that requires a new kind of type rating to fly, considering that FAR 61.195(b)(2) and (e) require the instructor giving a type rating (or any sort of instruction) in an aircraft that requires a type rating to hold a type rating in that aircraft, how is the first type rating for that new aircraft type issued?  Is it implicitly acquired by the flight test pilots, who then can give type rating exams and checkrides to other instructor pilots?  Or is there some procedure tucked into a dark corner of FSIMS that is used when "we need a brand new type rating, now what?"


texts: 777 small wing panel moving all the time during landing

texts:
What is the small wing panel called that moves up and down all the time during landing?

See the following video:

What purpose does it serve?


texts: What airline academies are available to US citizens?

texts: It seems that EU/Asian/Middle Eastern citizens have the opportunity to apply for several self-funded programs which (upon acceptance and completion) guarantee a job as a first officer on small twin engine aircraft flown by the sponsoring airline. Is there any such program available to US citizens? And if so, what makes an applicant competitive?


texts: Can you please identify this aircraft from a BBC show?

texts: The image is from:  BBC Skies Above Britain Series 1 "Flying into Danger" - Episode 1


texts: What is the appropriate fuel tank selection to land a 172?

texts:
On a recent checkout on a C172 I was told to select "fullest tank" as opposed to "both" that I have been doing for years. Given the aircraft is high wing (gravity feed) with no auxiliary fuel pump there should be no chance of sucking air.

Anyone know the correct selection?


texts:
This question is about the fuel pump controlled by the hydro-mechanical fuel control unit.

This is part of a fuel system for a turboprop engine, described on this page which actually comes from a Rolls-Royce book. Full picture for convenience.

I've been staring in vain at this picture for some time, with the hope that something will suddenly become clear:

Source

The pump is supposed to receive low pressure fuel and deliver high pressure fuel at a rate modulated by the FCU using fuel in the purple pipe. The engine speed governor also modulates the pump output.

It seems to be a piston pump, pistons being moved in translation by the rotating plate on the left side, but I'm not even sure, and I don't understand how this increases pressure.
It seems the governor is not rotating... and I don't get the role of the green governor pressure fuel.

Can you help me understanding how it works?
(I've posted all the details I could gather as an "answer").


texts: What are these suffixes used after the call sign?

texts:
I often play a flight simulator game Infinite Flight (http://www.infinite-flight.com) on my iPhone. The game lets you choose the following suffixes with your call sign.

Heavy
Super
Flight of 2
Flight of 4
Flight of 5
Flight of 6
Flight of 7
Flight of 8
Flight of 9
Flight of 10

I am aware what "Heavy" means but now aware about the rest. Can someone let me know?

Thanks


texts: Why did the Boeing Max operated by Lion Air disintegrate upon crashing in the sea from a low altitude?

texts:
The Lion Air Max crashed in the Java sea from a low altitude. What is the structural integrity strength of the fuselage?

I am curious to know the structural strength and integrity of commercial airliners like Boeing. The Lion Air doomed flight did not achieve cruising altitude of the standard 35,000 ft. I don’t know the exact altitude achieved but due to the MCAS triggering, I believe the jet didn’t reach cruising altitude. Why did the jet disintegrate upon impact from a mid-level altitude? I know it plummeted at 400 MPH but is there no structural strength to absorb the impact? Are jetliners not constructed to withstand high volume impact?


texts: Does an active pilot based outside the US require a flight review to maintain FAA currency?

texts: If a pilot is a holder of both Canadian and FAA commercial pilot certificates and is flying regularly in Canada, does this pilot still require a Flight Review to maintain currency of their FAA certificate?


texts: How are horsepower and standard displacement for a rigid airship calculated according to this book?

texts:
This is a follow-up based on a question posted here. I updated my initial question but came to the conclusion that a new post might be more manageable. For bibliographic reference(s) and/or getting a copy please refer to the linked question. Be that as it may, this is my current issue:
Having had some time at hand, I went back to the book. The solution of the problem set above continues like this:

Assuming the weight of the power plant and its cars to  be 8.lbs/Hp. and the weight
of the fuel and the fuel system to be .6 lb. per horsepower hour, the total weight
of power plant, fuel system and fuel is

[8 + ( .6 x 60 ) ] Hp. = 44 (Hp.)

combining this with the military load,

15,000 + 44 (Hp.) = .357

No issue so far, I was also able to compute this formula:

However, I cannot make heads or tails of the next part

Combining equations (1) and (2)

My question is how did the author arrive at equation (3)? Where does the value 48D(2/3) come from and how were these formulae combined.
When using the previously computed value of .0357 for D, I am not getting the result of 42,000.
Apart from the "actual" math involved, I fail to see the meaning of the components involved in equation (3):
Could someone help me out here and maybe translate that formula into English sentences?


texts: Is there a reason to be worried about go-arounds as a passenger?

texts:
The last night I had an "interesting" experience with an aborted landing, which was a bit dramatic for my liking. Heavy fog and darkness didn't help either. Pilot told us that the reason for aborted landing is a problem with navigation instruments.

Today I checked the flightradar24 data, which I've attached for your pleasure, but it didn't ease my worries since according to site's data the first attempt missed the runway completely.

How accurate are these flightradar's data?
How common is for pilot to miss runway in heavy fog?
Is there a reason to be worried while flying 50 feet above meadows in heavy fog? Possibly with malfunctioning navigation equipment?


texts: How to find trim condition of a sectional airfoil without knowing the angle of attack?

texts:
I am using a reflexed airfoil designed for positive pitching moments to achieve a pitching angle matched to the changing of free-stream velocity (Aerodynamically tailored).
I ended up with a pitching moment equation
$$
dM = c*Cm_{a.c} - (C_{l_0}+C_{l_α}*α)*Χ_{a.c}
$$
where $c$ the chord length, $Cm_{a.c}$ the pitching moment coefficient about the aerodynamic center of the airfoil $Cl_0$ the zero lift pitching coefficient, $Cl_a$ the lift coefficient at a certain angle of attack and and $Xa.c$ an offset distance about aerodynamic center.

I want to design a propeller and the data i have is free stream velocity, RPM, and geometry of the blade.
I assume a thin airfoil so the lift coefficient ($(C_{l_0}+C_{l_α}*α)$) is roughly $2π*α$ and $α$ varies with free stream velocity and rotational speed: $α = Δβ - tan^{-1}(V_{inf}/V_r)$ and $Δβ$ the pitch angle.

The idea is to find the ideal angle of attack $α$ that satisfies the pitching moment equilibrium condition $dM = 0$. However, pitching moment coefficient $Cm_{a.c}$ is also unknown.

*Let's say $X_{ac}$ value is given.

So, my question is how this equation can be solved? Can i get any other data from the airfoil's profile that help to find the solution?
Are reflexed airfoils have any characteristics that i should consider in such situation?


texts: What is the purpose of anti-skid surge accumulator in a 777-300?

texts:
What is the purpose of the anti-skid surge accumulator in a Boeing 777-300?

What would happen if it were not present and why is it only meant for the left landing gear wheel assembly?


texts: What factors should be considered to select jet-pipe or flapper-nozzle technology for a primary control surface?

texts: How is the servovalve mechanism chosen between these two mechanisms? what are their advantages and drawbacks?


texts:
Sometimes, when I am driving, I knock the car 'out of gear' or set the stick to the neutral position, to save fuel. This is most easily done when cruising down a hill or when you have some good speed and are approaching a stopping point, i.e an intersection.

Is there a flying equivalent for pilots? I'm wondering if during descent, or even a landing, fuel could (safely) be saved by reducing thrust to zero and gliding.


texts: Does a Navigation Specification characterize all legs of a terminal procedure?

texts:
I am studying the different parts of Instrument Flight Procedures, as they are described by FAA's manuals, such as the Aeronautical Information Manual, TERPS and Performance Based Navigation. For example, during the transition from the feeder phase of an Instrument Approach Procedure to the initial phase, I noticed that under certain conditions the procedure's navigation specification can be changed. For example, in RNAV GPS IAPs, feeder routes can be RNAV 1, while the subsequent initial and intermediate phases switch to an RNP APPROACH specification. Another example is during a SID or STAR procedure, where the navigation specification changes when the route crosses the circle defined by the associated airport and a 30 nautical miles radius.

  TERPS 1-8 2.b STAR/feeder and approach legs designed to cross within 30 NM of the ARP more than once do not change to RNAV 1/RNP 1/A-RNP (terminal mode) until the 30 NM limit is crossed for the last time. 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.

Having said all that, could someone help me to understand under which circumstances it is possible for the navigation specification of a procedure to change and, particularly, if it is more accurate to associate a navigation specification with each leg of a procedure, rather than having one navigation specification that characterizes the whole route.


texts: Do aircraft carriers always face into the wind?

texts:
When landing at a normal ground airport, the runway facing the compass point nearest to the heading of the wind is always operated, so that aircraft landing and taking off alway have to use the least distance of runway as necessary.

On an aircraft carrier the whole ship can rotate; so do they typically always face into the wind? How often do they rotate the ship if this is the case?


texts: Is there any obvious warning when auto-pilot is disengaged or when the mode changes?

texts:
Under the investigation section of the First Air Flight 6560 incident, it describes the catalyst for the accident:

  The approach was entirely flown on autopilot, which was correctly set to capture the localizer signal and track along the runway centreline (VOR/LOC capture mode). However, an inadvertent movement of the control column by the captain during the turn onto the final approach track caused the autopilot to disengage from VOR/LOC mode and revert to maintaining the current heading, resulting in the aircraft rolling out to the right (east) of the runway centreline.

My question: Is there any obvious warning (on common commercial aircraft, i.e. 737, A320) when auto-pilot is disengaged or when the mode changes?

I would have expected there to be an audible notification, some flashing light or something to make it as apparent as possible that something has changed, if it's as easy to change as 'nudging the stick'.


texts: How do I reinforce a tubular spar that has been drilled vertically for an attachment bolt?

texts:
Previously posted a question about lift strut attachment to tubular wing spar with a  bolt vertically through the spars.  See drawing below.

I tried using Bruhn's analysis book to formulate a a reinforcement to the tension and compression areas of the spar. I'm not an engineer, and need guidance.

I don't know enough or what formula to calculate the loss of strength due to the 3/8" bolt hole in the tension and compression surfaces of the spar.

I can provide the following data for calcualtions if that's helpful, the site does say to provide as much inofrmation as possible.

The eyebolt the strut attaches to is 101 in from the root, and the moment of lift at the strut attachment point from the outboard portion of the wing was calculated to be 10015.  WIth an OD of 2.00 and and ID of 1.75, the moment of inertia at the strut attach was .303.  This gave a stress developed at this point as 33,052.  Increasing the OD to 2.125  as in solution B increases the moment of inertia to 0.533, and reduces stress to 29940.   and OD to 2.25 in solution A to increases moment of inertia to 0.742 and reduces stress to 26994.  These were calculated with a safety factor of 1.5.

Does solution A create stress risers at the ends of the 2.25in external sleeve?   Does the solution B lack sufficient compensation for the loss of material?

@robert DiGiovanni... in this added drawing, the middle presentation shows the original design, the single bolt horizontal through two straps which connect to the lift strut.


texts: Will the pilot in a plane be able to tell if people are jumping up and down?

texts: If someone is jumping up and down in the bedroom of a private jet will the pilot be able to tell without listening? In other words, will the plane noticeably move?


texts: What is the history of "Joker" and "Bingo" fuel terms?

texts: Why do we use, in military aircraft, the words "Joker" and "Bingo" to indicate the fuel status of the aircraft? What is the history of these two terms?


texts: What would be the drawbacks of using a rotating engine as thrust reverser on airliners?

texts: What are the drawbacks for having engines mounted on an aircraft such that their direction can be hydraulically controlled for best performance and efficiency? The idea would be to turn the engine 180 degrees at landing so it can operate as a thrust reverser, even on jumbos like the Airbus A380 and the Boeing 747.  That would be some serious thrust reversing power.


texts: Is Engine up thrustline actually desirable for "speed stable" designs?

texts:
The much maligned Max 8 and the Buckeye Navy trainer.  What could they have in common?

Both would want static stability (trimmable speed stable approach) for landings.  Both would want maximum fuel efficiency for maximum range.

Engine up thrust would require less tail down trim for balancing forward CG.  Ideally, this could be optimized for cruise, so, at cruise airspeed and power, no tail down force is required, just like a plane with the CG back.  Much less drag.

The advantage is, once you drop out of cruise (less power), you now have a more staticly stable (read can be trimmed for one speed), making approaches to landing much easier.
Helpful for carriers and busy airports alike.

Is this such a bad design after all?


texts: What kind of airspeed does a (3D) GPS measure?

texts:
Assuming a GPS receiver is advanced enough to compute 3D position/velocity with reasonable accuracy, it can indicate not only the aircraft's ground speed (which ignores altitude changes), but something akin to airspeed as well. If there was no wind, this would be equivalent to true airspeed. In reality there would be wind so it is "TAS minus wind". Since this completely ignores the actual air (the value would have been the same if there were no atmosphere), however, calling it anything related to "airspeed" seems like a misnomer to me.
Is there a standard terminology for this kind of velocity measurement?
EDIT:
It seems my question was quite vague and providing more detail about what I'm trying to do would help. I'm writing the documentation for a GPS-based tracking device, which would be used in fixed-wing aircraft. The GPS is exceptionally good, with very high precision and quick sampling rate. It even provides very accurate speed, which is Doppler-shift based AFAIK. This data will be sent through telemetry. I'm trying to label the data channels in a way that would be useful for aviators down on the surface, so I'm trying to familiarize myself with the proper terminology. Therefore if I label this ("3D") velocity as "airspeed" (indicated/true airspeed), it will be misleading. If I label it "ground speed" (which is 2D), it will be misleading as well. My question is only whether a standardized name for this type of velocity exists; if there's nothing widely used, I'll just coin a name of my own (e.g. "3D velocity") and explain it well enough in a tooltip.


texts: How are "preferred routes" assigned if there is more demand than capacity on a route?

texts:
There might be multiple routes, belonging to the “Preferred Routes” class, connecting the same pair of airports.

However some of them might be more appealing for non-urgent circumstances such as less turbulence, more favorable winds, etc. Therefore there will be a route (as long as I understand) that is the desired one by many airlines at the same time.

Let’s suppose we have airlines A, B, and C requesting a flight on route x, but the capacity is one per route, or stated another way, only one of the three airlines can take the route and the other two must choose another route.

Which is the protocol followed to decide if the route x is assigned to A, B, or C?


texts: What is the purpose of the extending wingtip panels on the Su-25?

texts:
Is it to increase the air resistance of the aircraft?

Source: reddit.com


texts: Why does increasing thrust on one engine make the plane roll and not yaw?

texts:
If you increase the thrust on the right engine, the plane rolls to the left. But why? And why does the plane roll to the right and not yaw to the right?

Note: I am not a pilot, nor have I followed any aerodynamic studies whatsoever.


texts: How is lift transferred from rotor to chassis (or weight, the other way around)?

texts:
I am trying to find out how a helicopter rotor's lift is transferred to the chassis. Equivalently, how is the weight of the helicopter transferred to the rotor blades?

While looking for this online, I find a whole array of pictures of the drivetrain. The force enters the main gearbox (MGB), but leaves the MGB with a spinning axle going to the rotor. First I thought that something happens in the swashplate, but that is not well designed for bearing large amounts of force. So my thought is that somewhere in the MGB there is a nice piece of a bearing.

There is a question like this one for airplane propellers: How does the load transfer from a prop to the airframe? The bearings shown there cannot be found in the MGB of a helicopter (or, at least, I could not find them). It seems to me that a helicopter is hanging from its MGB. Can someone help me out? Pictures would be really appreciated.


texts: Why can't flight management systems receive instructions directly from the controller?

texts:
If an aircraft's flight management system has auto pilot and auto thrust coupling, and it can make changes to the aircraft speed and direction along the entire route without pilot intervention, then why can't controllers just be allowed to make these changes directly without the need to ask the pilot to do it?

Pilots and controllers would still be monitoring the aircraft should things go wrong, but gone would be the days of endless voice instructions like "Flight xyz turn heading 123 climb and maintain...join the localizer for runway xx" "Contact xxxx on 123.xyz"

So many accidents happen due to misheard or unheard voice communication between pilot and controller, along with the pilot's misunderstanding of how flight director modes work.

The FAA should make this a goal, much like adoption of ADS-B.


texts: How do cross-wind correction controls help while on the ground with wings level?

texts:
When taxiing, taking off and rolling out we are told to use cross-wind correction inputs. Assuming a headwind, you bank into the wind by raising the aileron on the windward side and lowering the other aileron.

However, it appears that just before you take off, even with the wings level, holding the ailerons as above helps the plane avoid skidding sideways on its wheels. I understand the physics once you are airborne and the wings are no longer level (you will slip into the wind). But what I don’t understand is why holding up aileron on the windward side helps prevent skidding sideways, even with the wings level.

How do the physics work to prevent sideways force on the gear? Or am I imagining that the wings are level and in fact the windward wing is lowered?

I’ve felt this more strongly in a Citabria 7ECA or similar light tailwheel, high-wing aircraft, but I think it also applies to a tricycle-gear C172 or similar.


texts:
Many aircraft manufacturers give names to the aircraft models. Piper had the Cub, Super Cub, and all the Comanche/Cherokee/Navajo/etc. names used in branding. Cessna has the Skyhawk, Skylane, etc.

Did Waco aircraft use anything other than the three-letter names for branding?

Edit: I am wondering about the original WACO aircraft, not the company that produces reproductions today.


texts:
I was wondering if there are regulations for when a flight requires both a pilot and copilot.
I always assumed a copilot is required once civilian passengers are aboard, but when I recently was a passenger in South-African and South-American sight seeing flights, the pilot was always flying alone. Flights in europe however always had a pilot and copilot.

Is this regulated by laws or can the pilot / airline company decide it on their own?


texts: What could cause uneven fuel levels in a Cessna 172?

texts:
I went for a 1.5 hour flight in a 1977 Cessna 172N, with several takeoffs and landings. I was alone. When I left, I had 18 gallons in each tank. When I arrived back, I had 15 gallons in the left tank, and 10 in the right tank.

Why was there such a disparity? Is this at all dangerous? Why did the right tank have less?


texts: What is this hatch above the cockpit of a 747?

texts:
There is a little door on the upper deck above the cockpit:

Source: Airliners.net, (modified to indicate location of hatch).

What is that door? What is its purpose?


texts: Will you be able to hear a supersonic aircraft flying away from you?

texts:
I'm wondering if you could be able to hear the sound emitted by an aircraft say traveling at Mach 2 away from you.

I wondered if it might shift the emitted frequencies beyond the audible range. Would you be able to hear it?