texts: What would be a simple aerodynamics simulation software for a student?

texts:
I have a project due 2 weeks from now that demands we make a glider using Styrofoam. I'd like to simulate the results as I plan my glider before I build it.

Which simple software, which allows importing a 3D model to do the testing on, can give me data on

CG,
CL,
lift,
drag and
reach

based on initial velocity, etc.?


texts: How many flight control shutoff valves are there in Boeing 737?

texts: I came to know from a source that there are total 6 flight control SOV 3 of which associated with each of system A and B hydraulic system .but in 737 FCOM under stand by hydraulic section in schematic diagram they have shown only 2 in total, 1 associated to each hydraulic system .so I am little bit confused .


texts: Is there anything better than LiveATC to get accustomed with RT phraseology?

texts:
I would like to "train my ear" for RT communications and I tried to listen to approach of Dublin's Airport. I simply can't understand more than 50% words because of loud background whistle and poor (quiet) sound quality, although the mp3 player shows 320 kbps. Do they sound just like that in real life too?

Is there anything else with better quality than LiveATC? I would like to get accustomed with ICAO phraseology, so US airports will not suit my needs.

Thanks for taking time to reply!


texts: Why is Thunderbird 5's number upside down?

texts: Why is Thunderbird 5's number written upside down?


texts:
An F22 has a higher thrust to weight ratio. The F22 has around ~70,000lbf thrust from its F119 engines, where as the F15 has around ~48,000lbf thrust from its F100 engines.

But every metric I can find indicates that the top speed of the F15 is higher than the top speed of the F22 (though I have not found a concrete reliable source on either).

How is this the case?


texts: How does NOAA's P3 Orion safely navigate hurricanes?

texts:
I've been watching NOAA's P3 Orion fly though Hurricane Matthew a bit on Flight Radar 24.  Looks a bit like this for the curious:

source

It's the only plane actually in Hurricane Matthew.

What I'm curious about is how they get through there safely?  I know they have done it with prior hurricanes, and I assume they have some sort of weather radar on board (being a NOAA aircraft and all), but I also assume there is much more to why that P3 is able to make it through a Hurricane without breaking apart.

Anyone have some insights into what makes this possible?  I'm especially curious about what they do to avoid the worst pockets of the storm (assuming they do).

And for anyone curious about how it looks like when that plane hits the middle of the storm, here you go:

source

Clearly there's not that much weather to avoid in the eye of the hurricane, but getting through those walls has got be pretty difficult considering all the wind shear.


texts: What are the implications of a Memorandum of Understanding during an aircraft order process?

texts:
The term "Memorandum of Understanding" often pops up when airlines are about to order aircraft.

I'm a little confused as of the importance it carries:

Does it contain any details if the agreement is broken?
Does it state when and where aircraft will be ordered? Or is it just "we will order from you"?
Does it contain any details on any discounts/benefits or similar? I imagine these would in some form be put down on paper before starting negotiations with which company to order from.


texts: Has the design-flaw with the Boeing 737's cabin-pressure switch been fixed yet?

texts:
At 42.21 minutes of this video about the crash of Helios' Flight 522 (a Boeing 737) caused by cabin depressurization, it was established that a major cause of the crash was a design flaw -- the main wire and the backup of a wire running from the cockpit to the depressurization valve runs through the same channel. So, if one wire burns up and fails, they both do. This is evidently contrary to safe design practices. Also, it seems that the cockpit instruments in the cockpit do not give sufficient indication during the preflight and takeoff checks that this problem exists.

From this video, it appears that this problem has not been addressed by Boeing. Is this still the position on current date?


texts: Pressure Distribution Pattern around Wing

texts:
it is clear that the overall integrated pressure on the top of the wing is less than the overall pressure at the bottom of a wing in order to produce a net nonzero lift force. Based on the attached figure below (AoA going from small to large), it seems that, for low and medium angles of attack, the pressure both at the top and bottom surfaces of the wing is lower than the free stream atmospheric pressure. The arrows' directions, from what I understand, are pressure gradients pointing toward higher pressure area, correct?
When the angle of attack is sufficiently large, the pressure on the wing's bottom surface is higher than the free stream pressure (positive pressure coefficient)...Is that correct?
Whenever the local pressure is lower than atmospheric pressure, I think air would rush to that area so air would be moving from far above the wing towards the wing top surface (same for bottom wing surface when the pressure coefficient is negative). Is that what happens?
Thanks.


texts: What are the prerequisites to join a flight School ? Is it different for each country?

texts:
(I didn't finish Highschool, failed French and math fml)

I've finished my 3 year diploma in Architecture.
I'm 23. Nobody has ever supported me and my dream to be a pilot. Not even my parents, heck they even found it funny, that I could even dream that.

But I'm not gonna stop till I drop.
I just wanna know if flight schools need a student to be a highschool graduate. Cause I've only got GCSEs no A levels.
  I have 6 GCSEs with physics chemistry and math being 3 of them, and C grade on most. Does that help?


texts: What fundamental differences separate low-budget airlines from traditional airlines?

texts: Low-budget airlines have made it incredibly easy and cheap to travel far and often, and yet at first glance they seem nearly identical to traditional airlines. Sure, you have to pay for meals, but a few dollars/euros here and there shouldn't make THAT drastic a difference. So what is it that makes a budget airline a budget airline?


texts: Why we need 1 hour for cooling after 3 consecutive attempts for starting the APU?

texts:
As it's said here(APS-3200 training manual (pg 268)):

we need 1 hour for cooling after 3 consecutive attempts for starting the APU. But why?
why not after each attempt? and why 1 hour?
is it valid for all APUs?
What about the jet engines of aircrafts? is there something like that for them?


texts: Why did my phone's GPS receiver stop working when the plane was descending to land?

texts:
Recently, I flew on an Airbus A320. I turned my Lenovo A328 Android phone into airplane mode, and then used the default Maps app to watch my position using GPS. For most of the flight it worked normally. However, at the end of the flight, at about the time the plane started to descend so as to land, the GPS position marker suddenly jumped to an obviously wrong spot. After that, it ceased to update — at least until I got out of the plane.

Is it expected behavior of a phone GPS receiver during a flight? If so, what causes it?

It seems the plane does need GPS itself to be able to, e.g., send ADS-B data, so it doesn't seem likely that it jammed the signal. It also doesn't look like the clouds could be an obstacle for GPS signals, since after the landing the operation of my phone GPS receiver resumed (being under the clouds).

For reference, here's flightradar24 data about my flight.


texts:
Which aircraft type flies the most annual passenger-miles?

I understand there are over 4,000 737s in service. However, there are over 1,300 777s in service.

These each carry more passengers, and presumably spend more time in cruise, where miles are clocked up fastest. Is it possible the 777 flies the most annual passenger-miles?


texts: What would be a safe minimum vertical separation distance between passenger-carrying multicopter aircraft?

texts:
There is increasing talk about employing passenger-carrying multicopters ("taxi drones") to extend urban mobility into the third dimension. These aircraft will have MTOMs in the range of several hundred kgs.

In case this catches on on a larger scale, airspace use will increase considerably compared to the current occasional helicopter and sight-seeing flight.

For safety reasons, presumably a certain minimum vertical separation will be required due to the downwash from the rotors.

Is there any information available about the current thinking on required minimum vertical separation between manned/passenger-carrying multicopters? Also, will there be any difference for this requirement between hovering and cruise flight modes?


texts: What is the format of the airport codes used in an ACARS OOOI message?

texts:
How are the departure and arrival airport codes in the OUT, OFF, ON and IN (OOOI) fields identified by ACARS and transmitted to ground systems?

For example, if my aircraft is diverted unexpectedly to Bangkok because of some emergency, will ACARS send the arrival airport code as BKK in the IN message? If so, how will it be identified?


texts:
Currently I'm working on my master's thesis on the topological optimization method of aircraft structures. I'm gonna to explore this method of design on the example of the pylon. Make something like this:

But firstly I need to provide information about conventional methods. Moreover I'll evidently need to compare old and new methods.

That's weird, but I've managed to find much more information about new method, although it is not broadly implemented yet. But seems that it's too few info on the internet about conventional techniques.

To be more specific I'm interested in that red caisson or frame on the picture below. How exactly it (or similar) is designed? Could you suggest some information (books, manuals, tutorials, abstracts... everything) about that. Russian text is also OK.


texts:
It's been a while since I tried to read a little about flight mechanics and aerodynamics, but I remember one question I had back then:

Is the thrust of a common passenger aircraft (A320, B737) greater than its lift-off weight and thus could it take off vertically?

A320:

Max take-off weight   73.5 (78) tonnes
Thrust range  98 (120) kN

73,5 tonnes = 73500 kg * 9.81 m/s^2 = 721035 N = 721 kN

If my calculations are correct, it could clearly not (a result like what one would expect intuitively)!

But how can the dynamic lift be larger than the weight using comparatively little thrust?
Rephrased: How can the dynamic lift be larger than the thrust?

Is there an invisible equivalent to gears at work here?


texts: Is the physical MAX8 design bad because software is required for the aircraft to stay airborne?

texts:
I'm not an aviator by any means, but one thing that has come up in recent conversations with friends is that the MAX8 is inherently unsafe because alone, unpowered, the craft is not 'aerodynamically stable'.

As we understand it, the new engine configuration means that the plane has a tendency to point upwards, requiring software to constantly point the nose down (which also seems kinda sketchy, cuz.. software). I imagine that if there was nothing to run the software, the nose would raise higher and higher until the whole thing was trying to backflip. I understand it wouldn't go totally vertical, but I guess maybe enough to stall or something else just as bad.

Is this true and is this the only aircraft with this kind of 'software or bust' design?

Edit:

My apologies, this question is probably pretty terrible for the majority of the people on this particular stack, but the thought has come up and been validated enough in conversations that I thought to ask folks here to get a better idea and/or be proven wrong (as has happened). I had no idea about phugoid or any of that kind of thing. I only really have "heavier engines cause the craft to pitch upward requiring software to point downward" and "software requires power to run" to base any kind of premise on. I appreciate your patience.


texts: Can a private pilot obtain a recreational pilot certificate?

texts:
While I'm thankful that third class medical reform has passed, I currently have a special issuance medical that the FAA has been reviewing for several months. This go around, they requested additional documentation further delaying the process.

I'm currently a private pilot. However, the aircraft I fly meets the requirements to be able to be flown by a recreational pilot. Looking at FAR 61.96, it doesn't look like I can "downgrade" my certificate with an additional recreational pilot rating per:

  § 61.96 Applicability and eligibility requirements: General.

  (b) To be eligible for a recreational pilot certificate, a person who applies >for that certificate must:

  (1) Be at least 17 years of age;

  (2) Be able to read, speak, write, and understand the English language. If the >applicant is unable to meet one of these requirements due to medical reasons, >then the Administrator may place such operating limitations on that applicant's >pilot certificate as are necessary for the safe operation of the aircraft;>

  (3) Receive a logbook endorsement from an authorized instructor who -

  (i) Conducted the training or reviewed the applicant's home study on the >aeronautical knowledge areas listed in § 61.97(b) of this part that apply to >the aircraft category and class rating sought; and

  (ii) Certified that the applicant is prepared for the required knowledge test.

  (4) Pass the required knowledge test on the aeronautical knowledge areas listed >in § 61.97(b) of this part;

  (5) Receive flight training and a logbook endorsement from an authorized >instructor who -

  (i) Conducted the training on the areas of operation listed in § 61.98(b) of >this part that apply to the aircraft category and class rating sought; and

  (ii) Certified that the applicant is prepared for the required practical test.

  (6) Meet the aeronautical experience requirements of § 61.99 of this part that >apply to the aircraft category and class rating sought before applying for the >practical test;

  (7) Pass the practical test on the areas of operation listed in § 61.98(b) that >apply to the aircraft category and class rating;

  (8) Comply with the sections of this part that apply to the aircraft category >and class rating; and

  (9) Hold either a student pilot certificate or sport pilot certificate.

Specifically (9). Is there a way I can exercise the privileges of a recreational pilot? I'm willing to take another knowledge test / checkride. Thanks!


texts: Are Helicopters allowed near busy airports?

texts: Are Helicopters allowed near busy airports or any airports at all and if not why not


texts: What to be considered in designing airplane tail (vertical and horizontal stabilizer, elevators and rudder)?

texts:
I would like to make a small amateur triplane with it maximum weight approximately 400 kgs with maximum speed 100 knots (180 kph). I have read many discussions about how to calculate the wing requirement in relation to the weight, the speed, the wing shape, the airfoil shape, and so on. Unfortunately not so many discussion I found here about tail part.

What is the aspect to be considered in order to have the right design? Tail parts I meant here are: vertical and horizontal stabilizers, elevators and rudder, including the airfoil shape and the area. This question is about low speed airplane only, not sonic and moreover the supersonic one.


texts:
I just accidentally discovered a few pictures on the web, that seem to imply, that there were some sort of airport security checks on passengers all the way back in the 1960-s. It was always my general understanding that airport security screening was not a thing before the Hague and Montreal conventions in the early seventies and the various national regulations that followed, so I was really quite surprised about the photos, but I have a suspicion that they could be dated incorrectly or the descriptions might be wrong.

For example, here is a press article photo, of what apparently is an early metal detector.

The description on the back of it clearly says that this device is to replace searching of passengers at the airport. Does that mean that all the passengers boarding aircraft were searched in some other way before that?

Here is another picture that left me puzzled.

It seems to be taken at Zurich Kloten airport, with passengers queueing for some booths, where, they will be "inquired on weapons". What does that mean, what is happening inside those things? Was there some kind of security procedure, exclusive to Swissair flights, or to the Swiss airports? If such a thing existed, when did they drop that, in favor of the normal screening? Those "ladies" and "gentlemen" signs look really weird...

And one more picture.

The uploader claims they found it on the Atlanta airport website, which then claimed this was a test of some airport security machine as early as the year 1960! I mean that was before the first hijacking of a commercial flight in the US, if I am not mistaken!
I think this one could probably be fake or a joke, or just something irrelevant to airport security. I do not think I see any electronic equipment here except for the data logger in the front, yet judging by the way the people are dressed this seems to be taken in the sixties, even though I am no fashion expert. The picture circulates in the web with this description, but I could not find any more information on it. And that just makes me even more interested to know what is actually happening there.

If anyone knows what these things are all about, and how it used to work back then, I would absolutely love to hear that. So any explanations strongly appreciated!
Thank You!


texts: Why is laser illumation of a cockpit an emergency?

texts:
Another answer pointed out that laser illumination of a cockpit may be considered an emergency, and that pilots may take evasive action when under laser illumination.

Why is laser illumination considered an emergency?

Have any documented instances of laser illumination resulted in injury to or loss of crew, passengers, or plane?


texts: What is the yellow marking underneath Delta A220 doors?

texts:
I've recently noticed a yellow marking underneath the left door of Delta A220s. It's a yellow rectangle with a black T on it and it is exclusive to Delta and no other airlines on the A220. Any ideas what it's for exactly?

Thanks!


texts: What visibility and cloud clearances are required for airplanes conducting visual approaches?

texts: What visibility and cloud clearances are required for airplanes conducting visual approaches during IFR while flying under FAA regulations? Is the visual approach a purely VFR maneuver requiring the usual VFR weather minimums for the airspace being flown? Or does the visual approach maneuver flown under IFR supersede normal VFR weather minimums?


texts: How does ATC know if you have been assigned a squawk or not?

texts:
Departing VFR from class D airspace, either you can request flight following after you leave the airspace or you may ask the airport ground/tower and they assign you a squawk code and setup the flight following for you.

For example, on a short flight from KCNO to KSNA, I usually get my squawk code from tower and after departure I switch to SOCAL and let them know I departed KCNO and usually follows by "ident".

How does ATC know if you already have a squawk code assigned to you or not?

How does initial communication with SOCAL differ from when you've been assigned squawk on ground before take off from when you want to request one?


texts: How are Victor airways defined and numbered?

texts:
I am wondering how Victor airways get determined.

What determines how many 'segments' they are? For example some airways connect two VORs only, while other airways stretch across (or "connect the dots" of) many VORs as they snake across the map.

Also, is there a numbering scheme?

U.S. freeways have a numbering pattern. For example, odd numbered roads run North/South, with their names increasing in magnitude from West to East (I-5 runs from Seattle to San Diego; I-95 runs from Maine to Miami). Is there anything like that in Victor airway system?


texts: If a winglet disconnected from an airplane mid-flight, what would be the consequences?

texts: I've always knew that the winglets on an aircraft provide lift. But what would happen if a winglet disconnected from one wing while a winglet was on another wing?


texts: Is it possible that commercial airliners use an EMALS or other form of electric launch?

texts: I am doing a big project for school over the summer, and was wondering if anyone can help? I just want a professional opinion on the idea. Is it possible or no?


texts: What is prop RPM control logic on PC-12?

texts:
Pilatus PC-12 has a constant speed propeller, but it does not have a prop control lever in cockpit, just a power lever and small fuel on/off lever.
So how does it determine the prop RPM? Does it simply maintain constant RPM at all times, or is there some predefined schedule depending on power setting and airspeed, and if yes, what?


texts: What was the Airfoil of Handley Page P.115?

texts: This extreme sweptback delta was built to test the Concorde wing at low speeds, sources say it had a biconv 6% airfoil, but I failed in finding data about it.


texts: How does a (non-pilot) arrange a tour of an ATC facility?

texts:
Although the question has been asked for pilots, how does a civilian get access to a ATC facility? I regularly listen to Live ATC, and I'm incredibly curious as to what the inner-workings of a tower look like.

Even at that, is there a live video feed of ATCs?


texts: How does the VOR receiver pick up the signal and how are the needles controlled?

texts:
Knowing the basic principle of a VOR and how it works, I am interested to know how the receiver works.

What exactly makes the needle deflect? And how does this deflecting mechanism know how much to deflect the needle?

So here is what I am thinking so far: since the signals are sine waves (I guess) and there are two of them, if you lay them over each other there should be a unique voltage for every direction from the VOR. To keep on guessing, this voltage is probably amplified and put onto a electric magnet that will then control the needle's deflection.


texts: Who bears responsibility when an aircraft takes off from the wrong runway?

texts: On occasion, an aircraft is cleared for takeoff on one runway, but actually departs from another runway.  This has resulted in embarrassment as well as catastrophe.  When this occurs, are both the pilot and the air traffic controller at fault?  Or is it only the pilot who is at fault?


texts:
The free route airspace is spreading in Central Europe, consuming routes and decomissioning VORs. There are no routes left in the high airspace, and some of the FIRs keep a few low (up to FL95) RNAV routes while others don't have any at all. Some ground-based navaids were decommissioned too. That means any and all IFR flight requires GNSS-based RNAV capability.
Is the training syllabus for instrument license changed accordingly to assume the licensee will always fly an RNAV-capable aircraft as that's required everywhere in their home country, or is there some way to train VOR, DME and NDB-based non-RNAV procedures provided?


texts: What is the purpose of proximity sensors on hydraulic systems?

texts:
One of the planes I worked on had ground spoiler response checked with proximity sensors. The reason mentioned for that was - "The ground spoiler is hydraulic only - hence its response will be checked with proximity sensors"

Landing gear control unit reads the proximity sensors and flight control system receives the signals indicating deployment of ground spoilers by landing gear control unit.

What are proximity sensors?

Why are they used because the surface is hydraulic?


texts: Where did the "K" identifier prefix for US airports come from?

texts:
Airports in the United States are (mostly) three letters, prefixed with a K. Where did this standard originate? Why K?

This is similar to "where did the U.S. N registration letter come from", but different!


texts: What are these circles around the propeller?

texts:
(Source: www.airliners.net)

These circles I believe are the wing tip vortex formed by the propeller tips or is it just due to the rotation of the propeller. How does this occur?


texts: Why don't modern jet engines use forced exhaust mixing?

texts:
Jet engines are noisy[citation needed] - even a modern high-bypass turbofan is still deafeningly loud compared to pretty much anything except the even-louder low-bypass turbofans or a turbojet (much louder still than even a low-bypass turbofan).  Unsurprisingly, making jets quieter has been a major concern for the entire jet age; as the majority of a jet engine's noise comes from turbulence at the boundary between the hot core exhaust, on the one hand, and the ambient air (turbojets) / bypass airflow (turbofans), on the other (along with, for turbofans, a small contribution from turbulence at the boundary between the bypass airflow and the ambient air), the primary means of doing this without needing a turbine-incineratingly-high bypass ratio1 is by making it so that the two or three exhaust streams mix smoothly, and preferably do so before going out the tailpipe (so that any noise that is generated during the mixing process can be trapped within the nacelle).

To this end, early jetliners used intricate forced-mixer tailpipes, which were extremely effective at mixing the exhaust and the ambient air, and, thereby, reducing noise; they could either be built into the engine at manufacture time, or retrofitted later on as a "hushkit".  These could be seen both on turbojets...2

...and on turbofans.3

With the switch to high-bypass turbofans in the 1970s and 1980s, the dramatically-increased bypass ratio of the new engines was enough all by itself to produce a large drop in noisiness, such that even a plain, unmixed tailpipe was acceptable, and the forced-mixer tailpipes of the earlier engines slowly disappeared from view as the numbers of aircraft using the older engines dwindled.

However, since then, the NIMBYs have gotten more exacting and noise standards have continued to grow stricter and stricter, forcing jets to again use exhaust mixing to make them quieter.  Two methods for doing this are in common use:

Chevrons

These sawtoothed tailpipe rims enhance the mixing of the core, bypass, and ambient air, reducing noise:4

Shared tailpipes

These engines simply send both the core and bypass airflow through a single, long tailpipe, where shearing forces at the boundary between the two airstreams create turbulence that causes them to mix to some extent before exiting the engine:5

Both of these methods, however, are fairly inefficient at mixing the different airstreams; a scaled-up forced mixer would be far more mixy (and, therefore, more noise-reducingy).  So why do modern high-bypass turbofans still use inefficient methods of exhaust mixing, instead of the more effective forced mixing?

1: A higher bypass ratio requires (for a given thrust rating) more power per unit turbine, which requires the turbine to run hotter.

2: Exhaust mixer of a General Electric CJ805-3 turbojet from a Convair 880 (image by Thomas R. Machnitzki, via DoxTxob at Wikimedia Commons).

3: Exhaust mixer of a Rolls-Royce Conway RCo.12 low-bypass turbofan from a Boeing 707-420 (image by Alf van Beem at Wikimedia Commons).

4: Exhaust mixer of a General Electric GEnx-2B high-bypass turbofan from a Boeing 747-8I (image by Olivier Cleynen at Wikimedia Commons); note the chevrons on both the fan cowling (here opened to appease the peanut gallery), for mixing the bypass airflow with the ambient air, and on the core tailpipe, for mixing the core exhaust with the bypass airflow.

5: Exhaust mixers of two General Electric/SNECMA CFM56-5C high-bypass turbofans from an Airbus A340-300 (image by Hansueli Krapf at Wikimedia Commons); two more A340s, along with their engines and said engines' exhaust mixers, are also visible in the background (one each at upper left and upper far right; please ignore the 747 at upper mid right).


texts: Helicopter Basics: How does lead-lag of blades actually help in compensating for increase/decrease in speed due to flapping?

texts:
I understand the following -

Due to dissymmetry of lift, flapping up and down occurs.
Since angular momentum has to be conserved, the speed of blade increases/decreases during flapping
up/down motion.
To compensate for this blade leads front by a certain
degree in the rotor plane, in advancing half and lags by a certain degree in retreating half.

My question is - what does the "compensation means"? Even after rotating the blade front by 1-2 degrees (leading), the speed of blade will remain the same after it is reached its maximum lead angle. So, what happens after that?

Is it the case that lead/lag helps in absorbing the load/vibrations by allowing some degree of freedom for blade to move by few angles?


texts: How do engineers log airplane maintenance?

texts:
Is there an encoding system that replaces the vagueness of natural language when it comes to logging aircraft problems or repairs that took place at a specific site on the airplane?

So, instead of someone having to enter a description like:
"Hydraulic fluid change at system ABC"
Which would be in their own native language and filtered by their own personal level of awareness, they could enter something like:
"GF65Z ABC"

Therefore, internationally, GF65Z could correspond to exactly that type of intervention with some hydraulic system and that would also make further investigation, in the case of some problem, easier.

Anywhere I can find more information about something like this?


texts: Could you start both A320 engines with APU BLEED on?

texts:
I've seen some procedures where one engine is started with APU bleed, then APU Bleed is turned off to avoid ingestion of non-desired gases and then the second engine is started with ENG 1 Bleed on.
However, my question would be: Would it be possible to start BOTH engines with the XBLEED Valve in the AUTO position, APU BLEED ON and assuming there are no critical issues (fire, ...)?
To sum up: XBLEED AUTO, APU BLEED ON. Could you start both A320 engines with that configuration?


texts: Could TCAS be used as a backup source for position, attitude or air data?

texts:
Given the number of incidents related to freezing pitot tubes, is there any current/planned implementation to infer aircraft position/speed/attitude/bearing based on TCAS data as a last resort data point? If not, is this at least doable?

Even if TCAS gives only relative data, one may correlate the data at the last moment before pitot data are lost to assist in dead reckoning.

Edit: I am not sure if my question has been misunderstood, or that I am misinterpreting the answers. The question is more like inferring current aircraft's data from transponders of surrounding aircrafts. Let's suppose at time $t_1$ I have planes A, B, and C within my TCAS range. I will possess information regarding their bearing, distance, speed, and altitude. At time $t_2$, even without my own altimeter, I can at least infer my own vertical speed using trigonometry. A, B, C are like ocean currents, a background moving together with me. If I know enough information about them, depending on what TCAS's underlying data stream provides, I can probably infer my own position, altitude, speed, and heading. From my limited understanding, TCAS bearing, distance, and speed are relative to me. However if I have not mistaken, despite what is shown on the screen, altitude is absolute measurement from the other planes' altimeter. One side fixed on a similar triangle, you'll get the rest.


texts: What is this scoop found on the core of a PW1127G engine near the CC/turbine section?

texts: The view is back to front, the scoop is at 10 o'clock on engine 1. What would be it's function? I need supportive literature as well if possible.


texts: Can helicopters land in a poor visibility scenario?

texts:
The Instrument Landing System and some others systems can provide to incoming aircraft guidance to the runway in poor visibility scenarios.

With that in mind, I have these questions:

Can helicopters fly in IMC?
Is there any system that can help the pilot land, just like ILS?


texts: What does the small fan do that is visible on Boeing 787 Dreamliners on landing?

texts:
When watching landing videos of 787's that are in service I've been noticing a fan that is located under the right rear section of the fuselage.  I've now seen it on 4 different 787's  from 4 different airlines.

Is this an emergency fan that's deploying, or is it just something that's designed to recharge some of the batteries on board?  Some auxiliary type of system, perhaps?


texts:
When should a transponder be turned turn on?

On the ground?
Always in flight?
Only when required: during radar service (flight following), above 10,000ft MSL, inside the Mode C Veil, or on IFR flight?

Should Altitude Mode be used whenever the transpoder is on?


texts: What is the status of a bravo airspace when the associated TRACON is evacuated?

texts:
On 18 March 2020, an earthquake struck just south of KSLC, causing an evacuation of the control tower and TRACON facilities.  The airport was closed.  Later in the day, I found myself unable to contact approach control.  The control tower at KPVU informed me that the TRACON was still closed, making radar services unavailable.

What I want to know is, does the bravo airspace stop existing when this occurs?  There was nobody to give me a clearance into the airspace.  Could I enter anyway, or should the airspace essentially be sterile?


texts: Is there a taxi turning radius requirement for normal category aircraft?

texts:
Does anyone know if there is any requirement regarding turning radius during taxi for a normal category aircraft?

I searched both the Part 23 and Part 91 from cover to cover and couldn't find any. If there is no legal requirement but a recommendation from some Advisory Circular or any other document I also would like to know.


texts: Can microbursts occur at high altitudes?

texts: I was wondering whether a microburst can occur at high altitudes?


texts: Descend via STAR, after getting crossing restriction previously

texts:
The ATC issues "Cross BHAWK at FL240" initially. After few minutes, the ATC instructs "Descend Via FYTTE5 arrival". Should we comply with the crossing restriction at BHAWK, or the restriction can be omitted?
The JO 7110.65Y says

Clearance to “descent via” authorizes pilots:

To descend at pilot discretion to meet published restrictions on a STAR.

and

“Climb via SID except after Baret, maintain flight level one niner
zero.”
NOTE1. Considering the principle that the last ATC clearance issued
has precedence over the previous, the phraseology “maintain
(altitude)” alone cancels previously issued altitude restrictions,
including SID/STAR altitude restrictions unless they are restated or
modified, and authorizes an unrestricted climb or descent. Speed
restrictions remain in effect unless the controller explicitly cancels
the speed restrictions.

However, the example given in "descend via" does not say anything about "previous assigned crossing altitude." And the note given in "climb via" example only explains the phraseology "maintain" would cancel previously issued altitude.
Is there any FAA document stating the altitude restrictions assigned previously can be omitted or still valid, after getting "descend via" clearance?


texts: What kind of materials is being used for Fighter jets glass shields?

texts: What kind of materials is being used for Fighter jets glass shields and is that different from what they use for commercial jets?


texts: What is the difference between en route and airway?

texts:
I am studying about airway now. But there are multiple terms that mean airway like enroute or air route. I don't know exactly what the difference is between them.

Airway, en route, air route, air path

I want to know the difference of meanings or definitions between above terms. Please tell me in detail.


texts: Why is Emirates not considering buying or leasing used A380s?

texts:
Airlines such as Korean Air are retiring their A380s. They are struggling to find buyers/lessors. In such a scenario, Emirates could easily obtain used A380s at cheap prices.

Is Emirates not leasing used A380s because of the costs involved in re-configuring of the aircraft? Since the A380 is an expensive aircraft, I feel that even with added costs in changing seating layout and maintenance of aged aircraft, it might be economical to consider used planes.

We have to also consider that since its the same aircraft, customers won't notice any difference in service or comfort.


texts: Why does a mid-wing aircraft have lower drag?

texts:
Why does an airplane having a mid-wing have lower drag than high- or low-wing configuration even if they have  wing of same shape and size?
This article (PDF) claims it's true.


texts: Do parking brakes lock the wheels and airframe together?

texts:
(YouTube) Wildcat undercarriage.

For planes with non-truck undercarriages, can they be rotated around the lateral axis of the main landing gear with the brakes applied without causing translation?

My answer is no, they must be locked and there must be translation (image below).

I had the following comment on a recent answer, and frankly I'm not quite sure, hence the question.

  [They] are wheels. The whole structure is free to rotate around this 'locked' axle...

I don't agree, imagine chocks are placed forward of the main landing gear:

A) Frame is locked, blue man can't lift as he can't cause translation.
B) Frame is not locked, plane rotates around wheels (from the wheels' perspective, they're free moving).

(Original) Above shows what I mean by translation, the plane moves forward (blue distance) with the wheel—plane frame (red lines) being locked. (Brakes are applied.)

Note: This question has nothing to do with deceleration or a running engine.


texts: Does in-flight Wi-Fi require regulatory approval?

texts: Does any country have regulations that require a certificate or approval of the aircraft that use portable Wi-Fi in flight? Is there an FAA or EASA regulation or advisory, or an ICAO document or advisory?


texts: What happens if Marine One's rotor blades fail?

texts:
While I was reading news, I came across this image of Marine One:

This is Sikorsky UH-60 Black Hawk

Citation of Image 1

Citation of Image 2

On a closer look, I see there are two big exhausts just under the blades at the top of Marine One. And there is also a big wing at the end of Marine One.

I know I would be wrong, but I am not sure about it: I thought these two things are inter-related to each other in case of rotor failure, i.e if the rotor fails then the exhaust would pump out air backwards like a blast giving it forward thrust, and the wing at the end would help it in direction or upward/downward thrust balance (just like in F1 racing cars). Essentially making it work like a plane for some time until it lands safely.

I tried searching about it, but could not get information about it. I did come across an older Marine One image whose exhaust is too small and is at the side rather than at the back and this does not have a wing at the back:

This is Sikorsky SH-3 Sea King

Citation of Image 3

Citation of Image 4

I have 3 questions:

Why is the exhaust at the back of new Marine One so big now?
Why is there a wing at the back of the new Marine One ?
What would happen if rotor blades of Marine One fail ?

Citations


texts: Would a sharper leading edge increase lift and reduce drag at lower speeds?

texts:
A recent scratch built glider kept turning to the right even after painstaking efforts to match the wings perfectly.  Extensive addition of fin area to the tail failed to correct it.  Closer examination showed the left leading edge had been carved to a sharper point, angled more sharply than the curvature of the wing.

After carving the right LE to a point the glider flew perfectly straight.

This was not expected at the 5-7 mph the glider flies at, and the effect seemed to be stronger at lower speeds.

Could sharper leading edges help even at very low speeds?


texts: What, exactly, happens when I call 1-800-WXBRIEF?

texts:
In the USA, calling the above phone number gets a pilot in contact with a flight service station (FSS). After reading the AIM and the Leidos Flight Service website, I still have some questions:

Where exactly are flight service stations, and which one does the phone number connect me to?
Is the person on the phone a meteorologist?

If not, how do they provide weather briefings?

Will someone answer 24/7 or do different stations have different hours?

Does this also apply to the FSS frequencies listed on VFR charts?


texts: How does the outflow valve work on a cabin pressurization system?

texts:
When you fill up a cabin with warm air the pressure of the cabin will rise.  An outflow valve controls the desired pressure. But with pressure rising doesn't the temperature rise because you're compressing air into a space? Is this why the outflow valve is there, to regulate the pressure and temperature? Does the outflow value open and close depending on the pressure during phases like climb, cruise, and descent. Or does the outflow valve shut completely once the cabin altitude reaches 8,000ft? But then wouldn't the air get too hot because it keeps getting shoved into the cabin?
Does it use the isothermal rule, if so then what is the work done?


texts: What is the A320's procedure for dual engine failure at very low altitude?

texts: What is the procedure for a dual engine failure in an Airbus A320 (perhaps a large bird strike, since these engines only tolerate medium birds) at a very low altitude, shortly after takeoff (approx 1,000 ft)? Additionally, will any procedure realistically save an aircraft in such a scenario?


texts: Does the direction of rotation of the propeller affect the direction of the thrust generated?

texts: Does changing the direction of rotation of the propeller from clockwise to anti-clockwise change the direction of thrust it generates?


texts: What happens when the logbook of an aircraft is lost?

texts: If the logbook for an aircraft is lost, how does one replace it? Is the airplane still airworthy?


texts: How to escape from an aircraft if the door is not armed?

texts: Following the question about arming the door, the link states that doors are usually armed before engine start. What if something goes wrong when passengers are already boading with doors un-armed how to escape from the airplane?


texts:
Why did the Avro Vulcan use a delta wing?

The B52, from the same era, used a swept wing, and had a higher maximum speed.

In the answer to What are the advantages and disadvantages of a delta wing compared to a swept wing?, Peter Kämpf explains that a swept wing is ideal for subsonic airliners.

No one else has built a subsonic delta-wing aircraft since, military or civilian. Why did the designers of the Vulcan make this unusual choice for a subsonic aircraft?

By Ministry of Defence [OGL 3], via Wikimedia Commons


texts: How does downwash bend airflow down? How can wing-tip vortices reach the airflow in front of the wing?

texts:
Wing-tip vortices only start occurring when the pressure difference on the two sides of the wing starts. Wouldn't this mean that by the time the downwash from the vortices is acting on the airflow it would already have bent on to the surface of the wing and could not be pushed down any more?

In this picture you can see that the flow is already on the wing and it can not bend down any further because the wing is there.

How do the vortices change the direction of the relative airflow before it reaches the wing? The vortices only occur on the wing so they should not be able to do this.

EDIT:
When I say downwash I am talking about wing-tip vortices pushing the airflow down therefore reducing angle of attack.


texts: Can the 737 Max autopilot be engaged when some sensors have failed?

texts: If some instruments on the 737 MAX 8 fail on the Captain's side and autopilot stops, can the First Officer engage autopilot (as the instruments on his side are fine)?  In the ET 302 crash the Captain tried to engage the auto pilot but it kept disengaging because of bad AoA readings (which in turn also affected other readings).  Could the First Officer have engaged the autopilot as instruments on his side were working fine?


texts: What is the threshold between high Aspect Ratios and low Aspect Ratios?

texts:
Oftentimes when describing flying organisms and vehicles, their wings are said to have a "high aspect ratio" or a "low aspect ratio". Sometimes the papers (that I read) gave the numbers, but more often, they would just leave the explanation at that.

So I was wondering, in general, what is the minimum ratio that would make it a "high AR" and what is the minimum ratio that would make it a "low AR"? Is there a threshold to be met, or is this analysis of AR rather relative and or subjective?


texts: How are fuel tanks tested and certified?

texts: What ground tests are carried out for testing and certifying wing fuel tanks for use in passenger aircraft? Is there any chamber to simulate flight conditions? If so, how is the chamber constructed?


texts: Can the signature of stealth fighters be uncovered, and then used for future detections?

texts:
A recent theaviationist.com article speculates that the reason behind the 'Combat Sent' and other SIGINT aircraft escorting the F-35's over Estonia two days ago was to deter Russia from using its radars—as their locations would be exposed.

Thinking about what harm could the radars have done, I have the following hypothetical questions not related to a particular aircraft / current world events.

Can an air defense system uncover the radar signature of a stealth fighter and use the findings to easily spot that stealth fighter in the future?
Can this information be passed on to the fighters so they can easily engage in beyond-visual-range (BVR) combat with that stealth fighter?


texts: How strongly is airband affected by severe thunderstorms in practice?

texts:
In light of this question I was very surprised to learn that despite operating on a higher frequency (108 MHz upwards) than the standard FM broadcasting, airband uses amplitude modulation (AM) instead of the much more robust frequency modulation (FM).

While amplitude modulation allows several senders/receivers to use the same channel and prevents jamming by the capture effect of FM, amplitude modulation should allow lightning strikes to disturb reception.

In Review of Measurements of the RF Spectrum of Radiation from Lightning by David M. Le Vine, NASA Technical Memorandum 87788 we see this chart in Figure 5:

I know that the AM broadcast band around $10^3$ kHz is severely disturbed in thunderstorms; airband is near $10^5$ kHz, so the noise should be being damped by a factor of -25dB (~ factor 1:300).

How is radio reception affected in practice?


texts: What's the benefit of cranked wing for commercial airplanes

texts:
Many commercial airplanes have a kink in the wing geometry.

A discontinuous change in the wing trailing edge sweep is present in the wing of the A320. What's the benefit of this? Is there any aerodynamic advantage?


texts: No alternate destination when flying from Oakland to Honolulu: is that correct?

texts:
When you file a flight plan from Oakland to Honolulu
  you put "Glory" as your alternate destination.[1]

Is that the correct way to file the flightplan?

Scanning back a few paragraphs, the airplane in question was a Cessna 402.

[1] B. May, Under His Wing: Adventures in Trusting God, p. 40 (Multnomah Publications, 1991. ISBN 0-930014-94-4.)

Please note while the publication is 1991, the actual copyright is 1979, so we are looking before that date.


texts: How does a pilot follow a holding pattern? Do pilots have to manually change heading and altitude (through the autopilot) each time they are making a turn? Or is it something the Flight Management Computer (FMC) can handle?


texts: Is it legal to rent out an experimental aircraft?

texts:
Is it legal to rent out an E-AB aircraft (not a light sport aircraft)?

The aircraft will not be used for hire or compensation but to rent out to a pilot who wants to fly from point A to point B.

After reading the FAR 91.319 I know the answer but seems like a lot of folks in this industry are confused on this topic.


texts: Is it normal to take off with limited flaps on a B737?

texts: Is it safe/normal to take off (fully loaded from Cyprus to Kenya - 6 hours) with very small flaps extended? Model of aircraft: Boeing 737-800. He used whole length of the airfield to take off, the next acceleration took a long time at low level, and the next climb happened very slowly.


texts: What will be the performance penalties of increasing the wing area of a delta winged aircraft to obtain a lower approach speed?

texts:
Delta winged aircraft such as the Dassault Mirage III have an approach speed of 170 knots as specified by the manufacturer.

The Mirage F1 was designed to have a lower take off and landing speed than the Mirage III, what would it have taken to reduce the Mirage III landing speed to 135 knots by increasing wing area and reducing wing loading, and installing the F1 engine, and adding leading edge extensions (without adding canards)?

Could this be done by reducing maximum speed to say Mach 1.4 instead of Mach 2 without sacrificing climb performance?

Some figures:
Mirage III
Thrust: 60.8 kN
Rate of climb: 83 m/s (16,300 ft/min)
Wing Loading:274 kg / sq m

Mirage F1
Thrust: 70.6 kN
Rate of climb: 243 m/s (47,835 ft/min) at high altitude

There is a formula relating change in stall speed to weight of aircraft, not sure if it is applicable here.


texts: Where can I find approved entry/exit points for Free Route Airspace (FRA)?

texts: How can I find approved entry/exit points for Free Route Airspace (FRA) in different countries?


texts: Are slats only used when there is a short runway or on all occasions?


texts: Why does exhaust flow inwards through a radial turbocharger?

texts: In a radial compressor, the air enters centrally and passes outwards, aided by centrifugal force. But, as the diagram shows, in piston-engine superchargers the driving exhaust gas flows inwards through a radial turbine. This has to fight against centrifugal force instead of leveraging it. So why is it done?


texts: What would be a suitable aircraft for a short haul freight forwarding business?

texts: I just graduated with an Aeronautical Science degree and I am planning on starting a freight forwarding company.  It would need to be high payload capable and relatively fuel efficient, the route that would be flown everyday is only 300 miles one way.


texts: What exactly was the American WW2 smokebomb used in naval warfare?

texts:
In WW2 the Americans used a kind of smoke/gas-bomb that they mounted under the SBD planes in naval warfare.

What was the purpose of that device and what is it called?


texts: How do VTOL aircraft like the V-22 Osprey not tilt?

texts:
How do aircraft like the V-22 not tilt under an unbalanced load? if they are only supported by 2 forces on either side a large weight in the back should cause it to lean backward when stationary, should it not? its hard to put this into an image but here goes nothing:

A large weight in the back would surely cause it to lean; original image source


texts: What are the requirements for a PPL to upgrade from SEL to MEL?

texts: Reading the requirements for MEL it is confusing which things must be done in a multi-engine, and which things carry over from SEL. If I already have SEL do I need to do a cross country in a multi-engine? Assuming I can meet the PTS for MEL, what other requirements are there?


texts: What are the regulations involved in aerial advertising?

texts:
I often see small aircraft flying at a low altitude around beaches and the like with banner advertisements trailing behind them on a rope sort of structure. I have a few questions about them:

What sort of permissions does it require (FAA) ?
Is this hazardous in any way (I believe there would be some
restrictions on this type of flight but is there an inherent danger
involved in such flights) ?
Are there any limits as to what altitude they are allowed to reach and
any restricted air space that they are only allowed to fly in ?


texts: How many versions of the P-51 dorsal fin fillet are documented?

texts: How many different versions of the P-51 Mustang DFF are there?


texts: Are military and passenger jets insured?

texts: Are aircrafts insured? Basically, I want to ask who bears the financial liability in case of some mishap? The airline company/government or some other company.


texts: What is the rationale for single engine military aircraft?

texts:
In aeronautics, redundancy is of primary concern. Having at least two engines is common for civilian aircraft. I expect the military to have at least the same level of redundancy. Moreover military aircrafts are prone to other failure modes such as bullet in the airframe over a territory in which they cannot easily land (e.g. mountains or desert in which pilots can be captured).

I will restrict this question to jet fighters but I think it can be extended to any military aircraft.

I expect modern fighters to have at least two jet engines for redundancy. This is the case for many of them (such as the F-22 Raptor, the Dassault Rafale, the Eurofighter Typhoon, the Su-27 family, the F/A-18 Hornet, and others).

Yet, some modern fighters have only one jet engine (for instance the F-16 Fighting Falcon, the Saab JAS 39 Gripen, the F-35 Lightning II, and the Dassault Mirage 2000). Thus I imagine there are good reasons to abandon engine redundancy, but I fail to see what reasons can outweigh such a feature, especially for military aircraft.

What are the reasons behind the design of a modern jet fighter with only one jet engine?


texts: headwind, tailwind, weight, density exponents for DR400/180

texts:
I am trying to build a ground roll chart for Robin DR400/180 following the procedure described
http://www.eaa1000.av.org/technicl/takeoff/topaper.htm#References. Does anyone know the tailwind, headwind, weight and density exponent to use for Robin DR400/180. Nothing is published in the flight manual.


texts: How much thrust is applied in a 737 to achieve taxi speeds?

texts: I'd imagine not much, but maybe none? I wouldn't be surprised if the plane moves forward without brakes alone.


texts: How are jet engines certified against birdstrikes?

texts:
I recall that during US1549's birdstrike incident that resulted in it landing on the Hudson, a large amount of migrating geese weighing upto 20lbs each were sucked into the A320's engines — far bigger and heavier than previously certified.

I believe that at the time the engines were tested & certified by throwing small chickens or similar, one at a time, into the engines. Has this certification process been improved at all since this incident?


texts: What are those sensors on the forward A321neo fuselage?

texts: What are those sensors on the forward (Airbus) A321neo fuselage? If it helps, this is WOW air's TF-DTR.


texts: As far as I understand, two of the reasons how an airfoil generates lift are Coandă effect and downwash. However, if there is upwash near the leading edge, why isn't an airfoil rotated by the two forces (upwash at the front and downwash at the back of an airfoil)?


texts: How does the power distribution change for a turbofan engine from being stationary to going at full speed?

texts:
I have found out that a turbofan engine of say an F-16 is producing zero power when stationary since $Power = Thrust × Velocity$. But assuming that the engine is producing the same thrust, it appears that regardless of whether the F-16 is stationary or moving, the engine is still consuming the same amount of fuel and therefore there is power output that is constant in both cases. I also found that the power I tried to calculate from the equation above is the propulsive power, so there must be something else that is consuming the rest of the power.

To make this simple, I will use some numbers. Let's assume a turbofan engine is capable of producing 100 kN of maximum thrust with no afterburner while consuming  4 kg of fuel per second. For the sake of simplicity I'm gonna use a figure of 30% thermal to mechanical efficiency for the engine that is constant through all of the following cases and which means that  there is 30% $×$ 4 kg $×$ 42  MJ/kg = $50 MW$ of mechanical power available at all times. With 43 MJ/kg being the heat value of the jet fuel.

Case 1: The engine is stationary and producing max thrust and therefore the propulsive power is zero so I assume that the 50 MW available is completely used in heating and accelerating the exhaust.

Case 2: The aircraft is accelerating and is now at half its max speed at sea level which is say 200 $m/s$. The propulsive power is now = 100,000 kN × 200 = $20$ $MW$ and so I'm also assuming that the other 30 MW remaining of the 50 MW available are still being consumed in accelerating and heating the exhaust.

Case 3: The aircraft reached its max speed at 400 $m/s$ at sea level. The propulsive power is now = 100,000 kN × 400 = $40$ $MW$ and as before, 10 MW are consumed by the exhaust.

So, if I understand this correctly, the power distribution goes from 0% propulsive power and 100% exhaust power when the engine is stionary to 40% propulsive power and 60% exhaust power when the aircraft is at half full speed and continues to shift the power available to propulsive power at higher speed until it is 80% propulsive power and 20% exhaust power. My question now is: In simple terms and with acceptable approximations, does this shift that redistributes the power from exhaust to the propulsive power as the speed increases really happen?


texts: How does washout affect the wing incidence required?

texts:
In theory: if I wanted to build an model aircraft with (zero zero) wing/tail incidence, how would washout affect the root incidence required?

E.g. if a wing has 2 degrees washout at the tip, would the root have 1 degree + incidence so that the 'average' angle of the wing is zero ?


texts: Must quadcopters have the same propeller sizes?

texts: I was flying quads today and it just suddenly popped up into my mind — do the propellers all have to be the same size in quadcopters? Mine are, but What if two propellers were larger and the other two smaller? The drone would still be symmetrical, but would it have any effect on the performance of the drone? Could you explain the physics behind your answer?


texts: How does a mechanic determine if a repair or alteration requires a Supplemental Type Certificate?

texts: How does a mechanic know when they have exceeded what 14 CFR Part 43 allows for a repair or alteration to an aircraft? They have thus entered an area where the repair/alteration is so significant that the Type Design has been changed, requiring a Supplemental Type Certificate (STC). Do aircraft maintenance manuals give the mechanic some limits to what he can do, or is AC 21.101 all they have to go on?


texts: Could a plane be constructed to be fly in fixed-stick roll-stable circles?

texts:
According to https://aviation.stackexchange.com/a/12511/973 it is not possible for a plane to aerodynamically recover from a roll disturbance.  Is that an inherent limitation of how planes could be constructed, or is that merely a design trait that is accepted in exchange for other considerations like fuel economy and ease of control?  Would it be possible to construct a plane such that if the controls were eased into a certain setting, the plane would settle into a stable spiral climb until it reached an equilibrium altitude set by the thinning air, and such that mild disturbances in the roll axis would settle out [possibly changing the plane's heading]?

I would expect that maintenance of roll stability during straight and level flight would be complicated by the fact that roll won't immediately affect the flow of air over a plane in the same way as would a change in pitch or yaw.  If a plane was flying in deliberate circles, however, I would think that a change in roll would rather quickly change the rate at which the plane would want to rotate about the yaw axis, and that aerodynamic surfaces cause such change to produce torque about the roll axis, thus counteracting the disturbance.

My intuition would suggest that even if roll stability could be achieved, a plane designed for such stability would probably be annoying to fly in normal usage.  If, however, it was possible to activate a control which would induce such stability, it would seem such a thing might be helpful in some situations where a pilot might otherwise be in trouble [e.g. unexpected sudden IMC or other conditions causing loss of visual horizon reference].  Would such a thing be aerodynamically impossible, theoretically possible but practically unworkable, or workable but not insufficiently useful to be worthwhile?


texts: Was the Horten Ho 229 flying wing a three-point-landing aircraft?

texts: The Ho 229's front wheel is visibly bigger than the main landing gear; during landing, did it touch down on all wheels simultaneously, on the front wheel first, or in the normal manner?


texts: What pilot safety features and equipment are on an A380?

texts:
What safety features and equipment protect the pilots (not, protect the plane) in the cockpit on a Airbus A380?
For example I know they have life jackets: but I wonder what else?


texts: How does a delta wing deal with supersonic boundary separation?

texts:
The question Why most of the supersonic or fighter aircraft use all-moving control surfaces? emphasis the importance of all moving stabilator for supersonic aircraft.

Many supersonic aircrafts fitted with delta wings (Concorde, mirage III, mirage IV, saab draken, sr-71,...) rely on elevons only for pitch control and thus cannot use a all moving stabilator.

How do they overcome the reduced controllability due to the boundary separation of the airflow at the trailing edge of the wing?

My question is focused on aerodynamic solutions (I know some aircraft can shift there CG thanks to trim tank, and some fighter are not aerodynamically stable in pitch but I want to focus on the boundary separation issue).


texts: Why pull up on the rollout after landing, after the nose wheel is down?

texts:
I'm a student pilot learning on a Piper Cherokee 180.  When I land and the nose wheel touches down my instructor wants me to keep pulling back on the stick through the landing roll.

For soft field landings this makes sense as you don't want the nose wheel to dig into the ground and tumble over.  However we are landing at an airport with hard surface runways which routinely experiences gusty wind conditions.  It seems to me that if I keep pulling up and a gust of headwind hit us shortly after the nose wheel touches down that the gust would lift the nose wheel back off the ground.  This of course would not be a good thing.  So in my mind I think it would be better to ease off the back pressure once the nose wheel touches down.  What are your thoughts?

Note:  My instructor was a crop duster so I think he just carried over the soft field landing technique and is just teaching this because this is what he learned.


texts: What is the resistance range for the Bendix King KN-64 DME Photoresistor?

texts: Does anyone know the resistance range for the Bendix King KN-64 DME photoresistor?


texts: What were the typical dimensions of a WW2 US bomber formation?

texts:
The idea behind daylight raids was that bombers were more accurate when they could actually see targets so the damage inflicted would be concentrated more so that a night time carpet bombing.*

All of the footage I see, including CGI in movies, depicts large formations of US bombers giving the impression that the "precision" raids were anything but precision.

What was the "footprint" of an average American daylight raid?  If you had to draw a 2D box on a map, what values would you assign to length and width?

*Not saying that it was done to protect civilians, clearly the objective was to destroy strategic targets.


texts:
How is an aircraft painted?

I've always wondered how an air plane was painted and what steps it required to accomplish this task.


texts: What instructions should I give to an untrained passenger for Hand propping Cessna 172N as a pilot?

texts:
Does anybody know what is the most effective way of hand propping a Cessna 172N, with a passenger who is not mechanically inclined.

So you need to give them the most easy to follow and simple instructions. Like after pulling the hand brake, and priming and opening the throttle 1/4 inch what do you tell them to do?

I would push the throttle gently in after I'd hear the engine coughing to power when hand propped, while keeping my feet on the brakes, till  engine's smooth revving and maintaining power.

But to a person that has no familiarity with the noise of the engine and does not know what to expect, what should I say.

Edit
I thought I should elaborate a bit to shed some light on what happened.

We had come back from a half a day of  hiking around the hills of Santa Ynez in the afternoon with my hiker friend. After trying to crank the ignition a couple of times, it just moaned jerking half way through a hesitant arc.

We looked around for something to use as chocks, found two rocks like 8-10inched and kind of heavy and pushed them to a locking position in front of the tires.

I set the throttle; told him not to touch it before I jump back after cranking and wave him all clear. Then he pushes the throttle by half an inch while pushing the breaks. We brought the engine back to life after a few tries.

After I felt we have a enough of prop rotation inertia I got on to the right seat and brought the RPM down. He got out and removed the rocks. Got back in and we flew back to Van Nuys.


texts: Are cargo and passenger flights flown differently?

texts:
Are aircraft flown differently because boxes don't complain about more abrupt changes in direction, speed, altitude, etc where passengers might. i.e. if the cargo is incapable of loading itself, is it subjected to a more aggressive flight regimen than if the cargo is self-loading and potentially complaint-filing.

I understand that Boeing, Airbus and other manufacturers produce essentially identical airframes in both passenger and cargo configurations, so they would have essentially identical flight envelopes, I just wonder if cargo flights are taken closer to the extremes.


texts: I heard someone talking about a position in the U.S. Air Force called an Air Battle Manager or ABM. What does a person in this position do?


texts: How does the Tactical Air Navigation (TACAN) system work? How is it different from the VHF Omnidirectional Range (VOR) system? Please explain in the simplest possible way.


texts: Can RNP AR APCH be defined as NPA or APV or PA?

texts:
How to define RNP AR APCH as a

  Non-Precision Approach / Approach with Vertical Guidance / Precision
  Approach?

or it varies when complying with different standards just like RNP APCH?

or it's only a special navigation method?

A document published by Airbus Safety First says:

  RNP and RNP AR procedures allow crews to fly approaches using internal
  and very accurate navigation tools, instead of traditionally using
  external guidance aids. They also allow the replacement of visual and
  circling approaches by instrument approaches, thereby enhancing the
  safety of airline operations. They are non-precision approaches
  although they provide the crews with cues and procedures similar to
  those used on precision approaches.

Click here, the
 2nd paragraph in  Introduction Part https://safetyfirst.airbus.com/app/themes/mh_newsdesk/documents/archives/performance-based-navigation-rnp-and-rnp-ar-approaches.pdf

How can it define RNP as only a NPA?


texts: Are crosswind landings performed using autoland or under manual control?

texts:
I believe many people here have seen at least one of Cargospotter's videos of crosswind landings at Düsseldorf (DUS/EDDL).
There are several of them. I picked this one:

I think the pilots land their aircraft manually in case of such heavy crosswinds.
But is that true? Or do they lean back and watch the scene as the autolanding system does its job?

This somehow related question suggests the plane is operated manually.

Are there any regulations as to when using autolanding and when to do it manually? I know this might be
opinion-based, but could autoland even handle these crosswind situations?


texts: How are aircraft separated in a non-radar environment?

texts:
In remote areas that have no radar (oceanic airspace, etc.) how is aircraft separation maintained so that airplanes don't get too close?

What do areas that normally have radar do when there is a sudden radar outage?  There are airplanes going everywhere, not necessarily on standard airways, and a lot of them are being given radar vectors.  What happens when the screens go dark?


texts: Have objective and verified tests been done of the effects of personal electronic devices on a commercial airliner's operation?

texts:
Have any governmental agencies done comprehensive tests on the effects of personal electronic devices used in the cabins (and cockpits) of commercial airliners?

With the ubiquitousness of cell phones, laptops, kindles, ipads, etc, it strikes me that everyone seems to just know that using a cell phone in the cabin of an airliner has no appreciable/measurable affect on the electronics of the aircraft.


texts: Can I continue school for the PPL in another country in another flight school, if it is still inside EU?

texts:
I am attending flight school for PPL at the moment at a flight school in Italy.

Next year I will study in Germany. It is possible that I will not have finished the PPL until then. Now theoretically the university is still very near at my home place (3 hours with the car), so I could somehow manage to finish my license.

However, would it theoretically be possible to continue my license in Germany at another flight school? I can speak Italian, German and English fluently, so language wouldn't be a problem.


texts:
I recently got into paragliding, but I am quite confused on how their controls work.

I am quite aware of how the control surfaces work on fixed-wing aircraft. Let's use for example an aileron. Lowering the aileron, increases the angle of attack of this wing, increasing lift, making the aircraft to roll.

On paragliders, things seem very confusing for me.

The theory

The control acts as a "brake". By pulling one brake there is an asymmetry in drag, causing the wing to yaw. Due to the yawing motion a difference in airspeed in the two sections of the wing causes a difference in lift, having as a side-effect the aircraft to roll too.

Thus pulling the right brake, makes the aircraft yaw to the right, and then roll to the right.

My thoughts

While one of the controls is pulled, the trailing edge gets lowered. This also lowers the aft-portion of the wing cord, increasing the angle of attack. I would expect that this would also increase the lift of this portion of the wing causing the to raise.

Thus pulling the right brake, makes the aircraft roll to the left.

For me, there seems to be nothing special with brakes. For example, in case of emergency (brake line failure), I can use the C-risers to alter the angle of attack of one part of the wing to turn. But then again the same paradox happens. I pull the right C-riser, the right wing has increased angle of attack, but still it dives!

How exactly do paraglider "brakes" work? What makes them behave as a brake, and not as an aileron?


texts: What is that extended nacelle feature on the Honda HA-420 HondaJet?

texts:
Here is a picture of the Honda HA-420 HondaJet with strange extended engine housings. Why are they required? What are they for?

I am not asking about the red covers, but the white engine housing features that I put a red circle around.


texts: Would it make sense to test the performance and handling of a prototype aircraft by mounting a free moving mock up on a track (like a rocket sled)?

texts:
https://en.wikipedia.org/wiki/Rocket_sled

When an aircraft is designed there is no way to find out if the maximum cruise speed is achievable with the chosen engine + wing + fuselage combination, and at what fuel flow.

Would it make sense to secure a section of high speed rail ( upto 320 kmh at least) to test full scale non flying models of light aircraft to get a better idea of what speeds could be achieved?

The fuselage could be sculpted and  changed repeatedly in a short time to test various drag reducing measures and forces could be measured accurately in real time. Acceleration times to take off speed could also be measured.

Edit: It does not have to be a rocket sled, just a tracked vehicle with the full size aircraft mounted on it as it is in this case with the NASA full size wind tunnel:

https://www.nasa.gov/centers/ames/images/content/109858main_AC91-0255-76.jpg

For designers of kit planes and LSAs, full size tunnel time does not seem to be an option, I don't know. The design team do well to mount their plywood or GRP prototype with its engine attached and run in on the track, controlled remotely and with some capability for movement up and down and limited movement in roll and pitch. An on-board pilot may be an option.

To test a new propeller or a cowling, or fuselage shape, or retractable gear,  wing design even, cycle times would be shorter, I think. The time to build a load bearing aerostructure, wait for good weather, time for take-off, climb and landing, not to mention test pilot time, all these would be reduced to zero - and postponed to a later stage once the design is finalized. All that is needed is to built a mock up capable of standing up to the forces on the track (2km should be OK) and the control system as well as the engine.

A typical test cycle would be as follows:

Build mock up
Test run on track and obtain data
Perform modification (replace cowl, wings, propeller etc)
Repeat the above

Considerable time and cost would be saved on the aerostructure, pilot time, fuel cost and safety would be very much better. Handling and stall behavior also could be safely tested out.


texts: Do financiers request IDERA's for small aircraft?

texts: Do financiers request IDERA's for small aircraft, or just large ones registered under the CTC?


texts: What throttle setting does an airliner use while cruising?

texts:
As a passenger, I have always felt like the engine are not kept at take-off thrust/full throttle a few (tens of) seconds after take-off, and so for obvious reasons as fuel efficiency, engine wear prevention, noise control for population in airport area, and so on.

I have also read on this site or on excellent Twitter account of the A380 captain Dave Wallsworth lots of explanation about how to reduce the take-off thrust (eg. flex temp).

But I cannot find any information about the throttle level (N1 percentage may be more accurate) during cruise. My guess is it is not constant because of weight decreasing during flight due to fuel comsumption, but this is only a guess.

I know Airbus airliners have a "CLIMB" position on throttle which allow the autopilot to set N1 automatically to reach cruise speed, but I would like to know how N1 value evolves during cruise.

A320 throttle quadrant with lever at CLIMB position, with auto-throttle range:


texts: Are you mandated to use a Fault isolation manual when clearing a defect on an aircraft?

texts: I operate a Bombardier Dash 8 Q400. I want to know if aircraft engineers are mandated to close or rectify a defect by only following the fault isolation manual (FIM). Can an engineer instead use his knowledge and experience of the systems to isolate the problem and resolve the defect?


texts: What is breaking away/peeling off in military lingo?

texts:
About breaking away or peeling off:

Is this synonymous of a wing over?
Is this a signal to your wing mates that you are leaving formation deliberately to engage the enemy?
Does that mean you would subsequently roll on your back to scan for possible enemy aircraft below, complete the roll, and proceed toward the enemy?


texts: Do flight regulations prohibit sleeping on the floor of an airliner?

texts:
During a recent trip in a Finnair A350, a couple traveling together was occupying 1 row of three Economy Comfort seats. During the 12 hour flight, one of the couple stretched out on the seats, the other one on the floor in between the seat rows, leg room being sufficient to allow this.

A flight attendant was overheard stating that sleeping on the floor was not allowed due to safety regulations. What safety regulation would prohibit this?

update

During cruise condition, no Fasten Seatbelt sign. EASA regulations. Yes you're out of your seat but we're allowed to walk around aren't we. Where is the hard, written, safety regulation?


texts: What if a aerobatic fighter pilot sneezes in middle of a maneuver?

texts:
No offense to any pilots, I am a student, curious.

I just watched Spy (2015) and I was just wondering what happens if one of the pilot accidentally sneezes during a difficult maneuver.

Jude Law misfires during a critical stand-off.

I mean what are the preventive measures taken to avoid this - the jet is obviously primed to be in best of its agility & stick-sensitiveness so can the pilots selectively decrease sensitivity of stick when needed?


texts: What is the best VFR route to CYKZ (ButtonVille) when approaching from the southeast?

texts:
I'm planning my first real life cross country trip from KFRG to CYKZ. But I'm very confused by the Toronto airspace. My main question is around how to approach ButtonVille airport from the south (say from Buffalo).

Option 1: Buffalo - Hamilton - hug the coast and drop from 3500ft to below 1700ft - ask CYTZ tower to transition thru to CYKZ airspace.
Option 2: Buffalo - Hamilton - Burlington Exec ( CZBA ) - Brampton Caledon ( CNC3 ) - ButtonVille ( CYKZ )
Option 3: I have flown from KFRG (Long Island) to N51 ( Solberg, New Jersey). This was done with my CFI who contacted New York Approach, told them where we were going and then the controllers ( we got handed off to several different controllers ) guided us over JFK and on to Solberg. Is this even an option? I don't see an option to contact Toronto Approach on the sectional.
Option 4: Just for the sake of completeness, there is the option to fly over the water, direct. But this is not recommended in single engine planes for safety reasons.

Can someone who has flown VFR to this airport before advise on this?


texts: What is ''reference turbulence intensity'' in 25.341?

texts:
14 CFR 25.341(b)(3)(i) says:

Uσref is the reference turbulence intensity that varies linearly with
altitude from 90 fps (TAS) at sea level to 79 fps (TAS) at 24,000 feet
and is then constant at 79 fps (TAS) up to the altitude of 60,000
feet.

Does this mean 90 fps (feet per second) is also the limit load? Or is the limit load higher than that?


texts: Do pilots have a generally preferred "traffic" resolution?

texts: For aircraft cruising along at altitude, it is common for the controller to assign an aircraft a new course or altitude or speed for some reason such as "for traffic". My question is, would most turbojet/turboprop pilots rather have a vector, say 20 degrees off course for 10 minutes, or have a different altitude, or have a speed assignment? What is most efficient for the airplane? Do companies have a preference? Are certain actions easier for the pilot? I suppose there is a fuel-use vs. time-en-route trade off in some cases, and many other factors as well, and personal preferences might vary widely, or maybe people don't really care?


texts: List of aircraft which are not certified to be flown by one pilot

texts:
Is there a list somewhere, where it says which aircraft are not single pilot certified?

My question is motivated by this question:

Fine for operating not single-pilot certified jet with one pilot


texts: What is the process for a TFR based on law enforcement activity?

texts:
Regarding the recently announced TFR for the Ferguson, MO area, what is the process by which such a TFR is granted?

The official reason given is "TO PROVIDE A SAFE ENVIRONMENT FOR LAW ENFORCEMENT ACTIVITIES", however, there has been significant commentary on social media arguing that this may be a politically-motivated act to prevent the media from scrutinizing the actions of law enforcement (for instance here).

As far as I know, there is no (public) information regarding threats to airborne vehicles, and despite some initial reports most of the protests in the area have been peaceful.  I'd like to assume that this TFR was created for legitimate, non-political reasons.

Is it common for the FAA to grant a TFR like this to local police?  What is the process by which this is done?  What criteria are considered by the FAA in determining whether such a TFR is warranted?

For the sake of posterity, the full text of the TFR NOTAM is:

!FDC 4/0271 ZKC MO..
AIRSPACE FERGUSON, MO..
TEMPORARY FLIGHT RESTRICTIONS. WITHIN AN AREA DEFINED AS 3 NM RADIUS OF
384428N0901812W (ST LOUIS VORTAC STL129011.0) SFC-3000FT TO PROVIDE A SAFE
ENVIRONMENT FOR LAW ENFORCEMENT ACTIVITIES. PURSUANT TO 14 CFR SECTION
91.137(A)(1) TEMPORARY FLIGHT RESTRICTIONS (TFR) ARE IN EFFECT. ONLY AIRCRAFT
PERMITTED UNDER THE PROVISIONS OF 14 CFR 91.137(B) ARE ALLOWED TO OPERATE IN
THIS 91.137(A)(1) TFR. THESE AIRCRAFT MUST BE OPERATING UNDER THE DIRECTION OF
THE UNIFIED COMMAND AT THE ST. LOUIS EMERGENCY OPERATIONS CENTER AND MUST
CONTACT THE MID-AMERICA AIR OPERATIONS BRANCH AT TELEPHONE 636-825-9341 OR
636-825-9342 FOR PERMISSION TO ENTER THE TFR PRIOR TO DEPARTURE. ST.LOUIS
GATEWAY TRACON, TELEPHONE 314-890-1017, IS THE FAA COORDINATION FACILITY.
MEDIA CONCERNS REGARDING THIS TFR SHOULD BE DIRECTED TO FAA PUBLIC AFFAIRS
THROUGH THE WASHINGTON OPERATIONS CENTER AT 202-267-3333. 1411250415-1411251015


texts: When does a 'flaps/slats misconfiguration' warning sound during takeoff roll?

texts: If a flight crew begins their takeoff roll and don't have slats and flaps configured properly, when does the system know when to sound the alarm? If it actually sounds during the roll itself, that seems a bit too late, as there then isn't enough time to deploy those surfaces. And it doesn't seem likely that the crew would have the time to look up a new V2 to figure out at what speed they can take off without flaps and slats.


texts: Why does the APU Master Switch flash during a normal APU shutdown?

texts:
Hi all and Happy New Year!!!

I have a question relating to APU shutdown procedures on Airbus A320. During normal APU shutdown sequences, I noticed that after around 1m20s, the FAULT legend on APU master switch will flash.

I wonder if the FAULT legend comes on to indicate APU intake flap is closed or any other reasons.


texts:
So far I have never come across any testing being done on having the ailerons and/or elevators on the leading edge of a wing, rather than on the trailing edge.
Does anyone know of such tests existing?
It somehow makes sense to me to have the controlling surface in the strongest part of the wing, which is not the trailing edge. Having all the 'heavy stuff' in front of the main carrying component, allows for a fairly light trailing part. Moreover the force applied on controlling the leading edge is less, because it changes the airflow without causing extra drag.


texts: Why don't modern aircraft have landing gear that can swivel to compensate for crosswinds?

texts:
When landing, crosswinds can be very expensive. They cause go-arounds, diversions to other airfields and even crashes.

Currently pilots crab in the air to counteract crosswinds and, at the last moment, throw the aircraft around to face directly along the runway. This is a challenging and risky manoeuvre - it can cause asymmetrical stalls and worse.

The nose wheel can already be rotated. If the main gear could also rotate, the plane could land in a crabbed attitude and continue that way along the runway until speed had dropped to taxiing speed.

How come aircraft don't have this feature?

EDIT

It has been flagged that this question is similar to a previous one, Is the main landing gear of a large airplane designed for sideways (crabbed) touchdowns?

My question is different. In those cases the landing gear does not actively turn to face in the direction of travel relative to the ground, it is merely designed to cope with the extra stress of hitting the runway obliquely. The allowed angle may be quite small. A swivelling undercarriage would allow for a large angle of crab with no attendant stress to the gear because the wheels would be aligned with the runway.

As pointed out on that other question, this design feature was adopted for the B-52. I am asking what factors persuaded designers to abandon this idea.

Videos (2) of B-52 landing in this manner
http://www.skilledpilots.com/video-this-is-how-a-b-52h-lands-in-a-crosswind-and-stays-completely-sideways-while-deploying-a-parachute-and-slowing-down-on-the-runway/


texts: I was recently having a conversation where the term "clearance delivery" popped up, and was talking about his time flying into PHX, but in all of my time flying, I've never heard of the term before! Could someone explain to me what exactly is this for, and where would you find this?


texts: Is there a relation between material choice and produced lift at rotation?

texts:
I'm currently learning about Rotary Winged Aircraft, and I have a question regarding lift and fluid flow.

Given two wings of different material but same shape, will there be a difference in the amount of lift, and the amount of air that is pushed down? Is the lift created related to the material choice in any way?


texts: Is there truly no way to get information about medical application status?

texts:
I had an event in 2005 that has not happened in the 10 years since.  When I went for a 3rd class medical the AME I went to seemed very skittish and wanted to send my records to Oklahoma City for review.  They received them the first week in March.

As we near the two month mark I have called and asked for a status once each week and have been struck by how little information they provide.  My application, for example, has been in the "handed over to the Doctors" status for almost a month with no new notations on the file.  This means I can't tell if it is sitting in the queue waiting to be processed, or is actually being processed by a Doctor who just isn't putting any notations in.  If I'm in the queue I have no way of knowing whether there are two or two hundred apps in front of mine.  In short, calling and checking the status is a worthless exercise.

In every organization I've ever dealt with there was always some way of going up the chain and getting some kind of information.  I'm told by the call center reps that is not possible.  I wanted to verify that information with the community here, though... is this just the way things are?  Is there no way whatsoever to get some useful information?  If anyone has been down this road and has tips they would be greatly appreciated.


texts: Why isn't a human required to confirm visually that flight controls are moving?

texts:
On this A380 flight  after pushback and engine start and before taxi, Capt Juergen Raps and   and Sr FO Harald Tschira  rely solely on their FID to check flight controls. On a regular flight without the Pilotseye.tv camera crew, they obviously can't see if flight controls respond.

Why isn't a human third-party (ground crew) required to confirm the flight controls' movements? This is obviously shrewder, and adds another safety measure to forestall the possibility that the FID shows a  flight control to move when it doesn't.


texts: In the United States, are ultralights legally considered aircraft?

texts:
I sometimes hear it stated that in the United States, ultralight vehicles are not legally considered to be aircraft. For example, Wikipedia used to state:

  In the United States ultralights are classified as vehicles and not aircraft, and are thus not required to be registered, nor is the pilot required to have a pilot certificate.

Under FAA regulations and US law, are ultralights considered to be aircraft?


texts:
Why isn't the Transition Altitude depicted on SID charts?

I would assume it would be a relevant information to be presented on this type of chart.


texts: What is the performance of a flat plate wing?

texts:
By flat plate I mean this:

Source: Physics.SE

Low performance indeed, but how much low? How would:

The angle of attack,
The speed range,
The turn capability,
The fuel consumption,
Or other significant characteristic

compare to the ones of some reference foil, e.g. a NACA 00xx?

Link to related benchmarks appreciated.


texts: What is the difference between an aviation training device (ATD) and a flight training device (FTD)?

texts:
According to FAR 61.57, the regulation requires different experience requirements when a pilot uses FTD or ATD for their experience minimums. So I have tried to look up the difference between those two but I don't really understand.

According to Advisory Circular 61-136A, the definition of ATD is a training device, other than a FFS or FTD, that includes

  a replica of aircraft instruments, equipment, panels, and controls in an open flight deck area or an enclosed aircraft cockpit.

The definition of FTD, according to FAR Part 1, is also

  a replica of aircraft instruments, equipment, panels, and controls in an open flight deck area or an enclosed aircraft cockpit

They look pretty much same to me.

Could you give me the examples of those two?


texts: What happens if you put too much oil into a reciprocating engine wet sump?

texts: Apparently putting too much oil into your airplane engine is really bad and can be expensive but why? Will the excess oil go out via the oil breather,... ? Thank you


texts: Does the extension of trailing edge flaps increase or decrease the critical angle of attack?

texts: Which graph is the correct representation of the trailing edge flaps' effect on the critical angle of attack? Does their extension increase (as depicted on the first graph) or decrease (as depicted on the second graph) the critical AoA?


texts: Could you use radial blowers to propel a model aircraft?

texts:
I was inspired by stealth planes like the Boeing Phantom Ray:

I'd like to make a model aircraft that's as thin as possible, and has integral engines that are not visible from the outside. I have been wondering how this might be possible.

One way might be to place a radial blower in the centre of the fuselage. Radial blowers suck in air through their rotary axis, and blow it out the sides.

Usually, they are housed so that air is constrained to come out in one direction. However, you can always give the air two exit ports.

I wonder if something like this might make a good engine for a plane? The air intake would be at the top of the plane, and the exhausts would be at the back.

Questions:

Would a single large engine have a power:weight benefit over two smaller engines?
Would the intake actually provide additional lift by reducing the pressure above the plane?
Might be intake be starved of air if the plane is acting as a lifting body?


texts: Why on weather surface charts high pressure is blue and low pressure is red?

texts: Is there any relation with the temperature of the air or is it just a standard procedure?


texts: Where does upward momentum come from in leading edge vortex?

texts:
I believe I am beginning to understand how a leading edge vortex creates lift. Faster air creates a lower pressure above the wing making lift.

But I am hoping to get another view of this in terms of momentum.

Does this vortex draw in air from above, pulling it downward and as a result lifting the plane up? Or is the vortex shed downward off the tail of the wing? How does this work?


texts: Will a diagnosis of psychosis ban me from getting my recreational pilots license or my private pilots license?

texts:
I want to get my category 3 or 4 medical so I can either get my private pilots license or my recreational pilots license. I have been diagnosed with psychosis and am currently on Invega Sustenna (anti psychotic) to combat the condition.

My question is: will I ever be able to get my cat 3 or 4 ? I live in Canada.


texts: Who designed and built Rans S-7 airplane?

texts:
I read in the Washington Times, that a man named Swingle, who has no knowledge and experience in aircraft design, built one which he called a bush airplane. But I read in Wikipedia, that the RANS S-7 series seems different as it was built by a company, Rans Inc, seems after the founder name, Randy Schlitter.

Does anyone know the complete story about the aircraft, the engine specification, the size, the weight, the dimension, etc, of that Rans S-7 as mentioned in the Washington Post article? It is interesting as it can land in a savanna.


texts: What's the best way to see accident rates for a particular make/model of aircraft?

texts:
I'm looking for a simple way to get NTSB safety statistics for different makes/models of aircraft so I can answer questions like:

How does the Diamond Aircraft safety record compare to general aviation over the last 5 years? All time?
How does does the Diamond Aircraft DA42 safety record compare to general aviation?
What were the (statistically significant) safest aircrafts in general aviation over the prior 5 years? What were the safest jets?

These are examples of questions. I'm mostly wondering if there is a tool or website out there that can help you answer these sorts of questions, or help visualize the NTSB data.

Thanks!


texts: Why do wingtip vortices affect the upwash ahead of the aerofoil?

texts:
I understand that wingtip vortices increase the downwash aft of the aerofoil and the theory that they will alter the effective airflow angle, reducing effective angle-of-attack, with the total reaction of lift acting at 90 degrees to Effective airflow, not the relative airflow which now has an extra component of induced drag.

But why does this happen? How do the vortices increase the upwash ahead of the airfoil when they occur rearwards of the wing?


texts: What factors determine where an aircraft can dump fuel?

texts:
An aircraft flying over a densely populated area–far away from the sea and mountains–declares an emergency, request fuel dump, and a landing as soon as possible. How does an air traffic controller know where it is safe/possible to dump fuel?

If this is regulated, then by whom or what is it regulated?
If it's not regulated, by what criteria does an ATC use to determine an area for dumping?


texts: How to read the propeller range chart for DHC-6 Twin Otter?

texts:
I understand constant speed propellers and beta range. However, I'm not completely sure I'm extracting everything from this chart that appears in a manual for a flight sim model of the Twin Otter.

Is this format common for describing propeller range in aviation?
Can someone describe the information exposed by the chart in words?

Source - Aerosoft manual


texts: Why do some IAPs lack an Intermediate Fix and/or include other fixes between Final Approach Fix (FAF) and Intermediate Fix (IF)?

texts:
I have noticed that some Initial Approach Procedures (IAP) do not mention an Intermediate Fix, but they do include at least one fix before the Final Approach Fix. Take, for example, this IAP of the JFK airport. It includes a Final Approach Fix (MATTR) but the one that precedes this (CORVT) is not labeled as Intermediate Fix. Is it always implied that the fix before the FAF is the Intermediate Fix? Another example is this IAP, also of JFK, where JAMCA appears to be the Intermediate Fix but, nevertheless, is not labeled as such.

In addition, there are some IAPs like this which neither include an Intermediate Fix, nor have the last fix (in this case, CEMUG) labeled as FAF. In this particular example, RUSHY, instead of CEMUG, is labeled as FAF.

Is there any rule which I am not aware of and that will help me clarify the above cases?


texts: Can the load factor during glider winch launch be measured with the G-meter?

texts:
I am looking at the flight envelope of a glider, the velocity - load factor diagram. I read that generally the air-frame, the G-meter and the pilot 'experience' the load factor as a G force (an acceleration).
My question is whether that is always correct. I think of a winch launch and believe that in this phase, because of the cable, the the G-meter and the pilot do not 'experience' the load that the air-frame has to deal with. Or in other words, there is load on the air-frame which is not due to acceleration. But I do not clearly understand the physics of the launch phase.
The question is important to me because if my believe is correct then during launch the pilot cannot judge the stress on the air-frame by the G-force he/she feels.


texts: When do I need to worry about a course deviation indicator reverse sensing?

texts:
I understand that if I am tracking a radial inbound I will set that radial as the reciprocal so I don't have to worry about reverse sensing. On an approach however, do I need to set the CDI to the reciprocal? If I go missed and track the same course outbound do I then leave the CDI on the same heading?

On this approach plate, which was talked about here, why is the back course on two different sides (one is shaded on the left, one is shaded on the right)?

How does a front course and a back course affect your CDI settings?

Are there any difference between these two CDIs?

(And also, why is it labeled a VOR receiver? I thought both of these instruments were called Course Deviation Indicators.


texts: Can you change airways when they cross without a named fix?

texts:
There are a few victor airways that cross without a named fix, just two solid lines drawn over each other on the IFR low charts. Can these be used as intersections for changing airways in IFR route planning? Assuming you are above MEA for both, prior to the crossing. They aren't very common but I happen to have one very near my usual airport that along with a poor DP makes planning for certain directions rather tedious.
Examples

the crossing of V55 and V170 just north of JMS VOR on chart enroute L-14 North Dakota;
V495 and V23 with V187 over Tacoma(this one may be due to SEA class B) ;
V183 NE of RZS near Santa Barbra, could you plan to turn north from V183 onto V485 or V107?