texts: Why was the FDR of flight ET409 extracted from ocean transported dry instead of in water?

texts:
I was more than sure that FDR (as good as any other electronic device including magnetic strip, i.e. HDD), after sitting for a few days under the sea or ocean, must unconditionally be transported wet (i.e. inside some water container) to simply not let magnetic strips to get dry. The answers to this related question confirm this.

Yet, I have just saw a reconstruction and investigation of Ethiopian Airlines Flight 409 crash and noticed that:

FDR (found and extracted first) was transported dry, enclosed in an empty box,
CVR (found and extracted few days later) was transported in a box filled with water.

Is this just a "bug" in movie or can FDRs be transported dry after extracting them from sea / ocean?


texts: What type is this Syrian light attack aircraft?

texts:
I saw the following 2012 photo of a light ground attack jet used by the Syrian regime in an attack on Tel Rafat:

I do not recognize the type, however, and it does not appear to be any of the regular ex-Soviet types normally flown by the Syrian air force (MiG-29, MiG-25, MiG-23, MiG-21, Su-24, Su-22). Does anybody know what it is?


texts: What are the minimum requirements for a student to solo a second make and model aircraft?

texts:
Suppose I've done my Private Pilot training in aircraft Make/Model "A" and the one I have access to breaks two weeks before my checkride.  My instructor also teaches in model "B".  What do I need to do solo in model B, if all of my endorsements are for model "A"?

Is it necessary to complete a Pre-solo exam?
Is it necessary to demonstrate all the maneuvers in 61.87?
Is it necessary to demonstate all the maneuvers in 61.93 for solo cross country privileges?


texts: Are there any airports that do not have an IATA code but have a huge number of traffic?

texts:
I am collecting a list of all airports in the world for my project, at present I have 46000 airports in my database but only 7000 airports have IATA code. So my question is, if I only take 7000 airports with IATA code and delete the rest will I lose any major airports or airports with huge traffic.

Are there any airports that have no IATA code but do have a huge passenger traffic or provide connections to major airports?


texts: Do airliners have an "anti-pilot" warning system?

texts:
In February 2014 a co-pilot hijacked Ethopian Airlines flight 702 and took it to Switzerland.

Now in March there is some speculation that Malaysia Airlines flight 370 may have been hijacked and destroyed by the pilots - maybe they took a nose dive into the Andaman Sea?

So my question is this: is there an automatic or say anti-pilot warning system on commercial airliners?

In other words, a system that is non-maskable (can't be disabled by the pilot) and which will automatically warn ATC about unexpected conditions (like a sudden decrease in altitude)?


texts: During which phase of the mission profile, the airplane fastest?

texts: In a mission profile, there are various phases such as Climb, Cruise, and Descent (excluding other phases). My question is during which of these phases, the Mach number of the airplane is highest? Is that Mach number more or less than critical Mach Number?


texts: What is nominal n1 and fuel flow behavior during cruise climb?

texts:
For a commuter airliner (e.g. 737) performing a cruise climb (step climb) at a constant Mach, how should n1 and fuel flow behave?

I know that fuel flow should decrease with altitude (air fuel ratio).
Should fuel flow also decrease with weight (fuel burn off)?

Is n1 kept constant? Does it decrease with weight? Is it unaffected by altitude?

If it depends, then what systems (fadec?) or settings (rated/non-rated mode?) are responsible for setting the behavior.


texts: Does the FAA verify or authorize VFR flight plans?

texts:
It's possible (and, at least by AOPA, encouraged) to submit flight plans for VFR flights, but ATC still do not perform many of the services they provide for IFR.

Suppose I submit a flight plan for a Piper Cub under which I take off, climb to FL10,000, and dock with the International Space Station before landing on the White House front lawn? Or, slightly less egregiously, a plan under which I clip an ADIZ but I don't mark it as DVFR?

Will the flight plan be rejected when I try to submit it? Will Flight Services refuse to open it? Will they open it anyways and just let me do my thing?  Are they required to verify it in some way?


texts: Do propeller coefficients go to zero at the same value of advance ratio?

texts:
Graphs of power coefficient ($C_P$), thrust coefficient ($C_T$), and efficiency ($\eta=JC_T/C_P$) of the 5868-R6 propeller as functions of advance ratio ($J=V/(nD)$) and propeller pitch (blade angle at 0.75R?) are found in many textbooks (such as McCormic):

From these curves it seems that for a given propeller pitch $C_P$, $C_T$, and $\eta$ go to zero at the same value of $J$. At also seems that the slopes of the $C_T$ vs $J$ curves for higher value of $J$ (where $C_T$ approaches zero) are the same.

I have two questions:

Do $C_P$, $C_T$, and $\eta$ always go to zero simultaneously at the
same value of $J$ for all propellers?  Why?
Are the slopes of the $C_T$ vs $J$ curves where
$C_T\rightarrow 0$ the same for all values of propeller pitch?


texts: Is there a better solution than the U-shaped tailplane for this Airbus concept?

texts:
Image source: airbus.com
This U-Shaped tail is from a concept aircraft from Airbus, I was wondering if there is an alternative but just as good solution to the U-shaped tail. Using a canard in the front for pitch and winglets on the wingtips?


texts: Does the center of lift have to be in line with the center of mass?

texts: Imagine 2 theoretical planes, A and B, shown in the image below. The center of mass is yellow, and the center of lift is blue. Would plane A and plane B work as well as an airplane with the center of lift in line with the center of mass or no?


texts:
The 737 MAX 7 is the smallest of the four major variants in Boeing's 737 MAX product line; it is intended as the successor to the highly-successful 737-700, and features a higher fuel efficiency, considerably greater capacity, and increased range compared to the 737-700.  Yet it is selling very poorly, with only 58 orders so far - and 23 of those 58 orders, from MAX 7 launch customer Southwest Airlines, have been deferred until the mid-2020s, raising the possibility that Southwest might cancel those 23 orders entirely.

Why are the airlines which enthusiastically jumped at the -700 balking at its successor, despite its being the longest-ranged 737 ever (the MAX 7 can fly for 7,130 kilometres before it needs to refuel), thanks to its increased fuel efficiency, and having a capacity of 138-172 passengers, as compared to the -700's 138-140 passengers?


texts: Do turnbuckles twist the flight control wires?

texts: When adjusting a turnbuckle on any flight control, we usually use a wrench and turn the hex shaped section of the rod end inserted into the turnbuckle barrel. That flight cable from the turnbuckle is connected to a stationary non rotating component, but when we turn it aren't we just twisting it at that point, which causes stress loads on it.


texts: Is baggage always offloaded when a passenger does not travel?

texts:
For terrorism concerns I think many airlines offload checked in baggage if a passenger somehow does not end up travelling on a flight.

How strictly are these rules followed? e.g. If a connecting passenger with a tight connection cannot make it to the gate in time will the airline actually send in a ramp guy into the baggage hold to remove specific pieces of baggage? How feasible is it to do thing when the bags are in pods or the Unit Load Devices? Do they have to remove the load device from the hold before they can extract a specific bag?

How does the gate delay of just waiting for the errant, late passenger compare to the time & effort needed to find & offload his bags?

PS. Since bags do get misrouted I'm sure at least some bags fly without a passenger owning them on board.


texts: Is there any reason for why the cabin temperature would suddenly become very high?

texts:
I was flying a Fokker 100 a few months back over central Europe. We had probably just reached cruising altitude when the cabin temperature suddenly skyrocketed without reason, with the air coming out probably around 30 degrees (Celsius). After complaints by fellow travellers it became cooler. Is there any reason why it would do this?

I guess the pilots might have done it, but I see no reason for it, so could the aircraft have done it on its own accord?


texts: What is the difference between Cloud Ceiling and Cloud Base?

texts:
By definition, Cloud ceiling is The height above the ground or water of the base of the lowest layer of cloud below 6000 meters (20,000 feet) covering more than half the sky.
So does, Cloud Ceiling become Cloud base if it is covering less than half of the sky.
Thank you for your time.


texts: Why is tailwind during final approach and landing so dangerous?

texts:
I understand that tailwind is typically a good thing during your flight as it increases your ground speed and gets you to your destination faster.  Despite that I get a feeling that pilots typically get very uncomfortable when there is a significant tailwind present during landing.  Sadly, recent proof of this danger was in Aspen, Colorado accident

Questions:

Why are tailwinds bad during landing?
Given "extra long" runway for extended rollout, are there any dangers with landing at a higher ground speed?
How are tailwinds mitigated?  Would ATC just switch the landing direction?


texts: Need to add elevator downforce to total lift when sizing wing area?

texts:
Do I need to add elevator downforce to total lift when sizing wing area?

Say a small airplane weighs 1,000 lbs, and both the wing and elevator have a max Cl of 1.5, and my elevator is 20% of my wing area, so max elevator downforce is roughly 20% of 1,000 lbs or 200 lbs in a classic configuration.

Doesn't the main wing then have to carry 1,000lbs + 200 lbs negative elevator
lift, for a total lift of 1,200 lbs?

If the plane is in a tandem configuration, the main wing would only have to carry 800 lbs, as the elevator has 200 lbs of positive lift,for a total lift of 1,000 lbs.

1,200/800 lbs is 150%!!, so if I use the tandem configuration, my main wing can be 50% smaller!!! Is this correct?


texts: Why do some airfields not have manned ATC towers?

texts: I was wondering why some airfields, for example Tatenhill Airfield (EGBM), don't have anybody in their ATC towers?


texts:
Is it possible to have a minimum wing loading at climb segment of our design aircraft (air superiority)?
Which segment would have minimum wing loading i.e. climb, take off, cruise, instantaneous turn, sustained turn, etc?


texts: Disadvantages of using thrust vectoring only in an aircraft with variable rotation nacelles such as the X-19

texts:
Take a quad tilt rotor aircraft such as the curtiss-wright X-19 or even a bi-tilt aircraft such as the V-22.

What would be the advantages or disadvantages of using thrust vectoring only for control of roll, pitch and yaw assuming for a moment that there is no added mechanical complexity in individually tilting each nacelle a variable rotation and assuming each nacelle can tilt 180 degrees from full vertical producing downward thrust (lift) to reverse vertical, essentially sending the aircraft downwards.

In theory, the front two nacelles would control pitch by rotating up or down simultaneously while the back two nacelles would control roll by each nacelle tilting oppositely. Combined all nacelles would be capably of controlling yaw or by changing the thrust being generated on each side of the aircraft, a yaw moment could be generated.

of course there are clear issues in the form of Cost, mechanical complexity, control of the aircraft in an engine out scenario, gyroscopic moments and control generally but purely from a flight mechanics perspective, what are the advantages or disadvantages of removing ailerons and using thrust vectoring to control the flight of such an aircraft.

Currently, it is my belief is it would allow the use of highly complex airfoil geometries that would increase the efficiency of the aircraft in flight as airfoils would no longer be necessary and perhaps increase maneuverability of what i would imagine to be large aircraft but there is no drawbacks other than those previously mentioned however, would thrust vectoring produce less turning moments than ailerons?

I look forward to any and all replies, thank you.


texts: do you have to go to the air force to be a commercial pilot


texts: What are the layers of a pressurized fuselage (cross-section and construction)?

texts:
I've looked all over this site, and also Web searches - but I can't seem to find any discussion about, and the construction cross-section of, a commercial airliner's pressurized fuselage wall.  Not the cross-section of the whole cabin, but just the fuselage wall from inside the cabin to outside.

More specifically, I'm curious as to what layer (and where in the cross-section) contains the pressurized compartment.  Do the circular ribs (or whatever they're called) contain this layer, or is the outer skin the pressure vessel?

I've already seen the below questions (and their answers), but they deal primarily with cabin/cockpit window construction.

Why is there a hole in one of the layer of an airplane's windows?
Why do airplanes have curved windows?
What materials are plane windows made of?


texts: Meaning of XX below Slat FLap Trim on A350 with flap setting 1

texts:
What is the meaning of the 'XX' in amber below the 1 (in green) within the Slat Flap Trim section on the A350 PFD when the flaps are set to 1 with the correct speed (below 255kts)?

See picture attached. If the flaps would have failed, it would indicate XX without the 1. So, what else could this XX indicate?


texts: Are military aircraft required to have black boxes?

texts:
In the United States, the FAA requires certain types of aircraft to have a Flight Data Recorder (FDR) and/or Cockpit Voice Recorder (CVR).  I understand these regulations to apply mostly to civil aviation.  Does it apply to military aircraft as well?

Another question researched whether fighters have them or not; my question is whether they are required to, and for military aircraft in general, not just fighters.


texts: Can a US airline add an employee passenger as crew?

texts:
Suppose an airliner flight is full with passengers and the airline staff realize afterwards that there are employees who the airline wants to send to their shifts using that flight.

The airline staff decides to ask for volunteers to surrender their seats in exchange for compensation, but they don't get enough volunteers to make room in passenger seats for their employees to take.

Would it be legal for the airline to instead have one or more of the employee-passengers take the flight as "extra crew" (assuming there is an extra seat to strap into in the crew areas)?


texts: What are these "patches" on an Airbus A321 wing?

texts:
While on a WizzAir flight I noticed on the wing the patching marked in this image:

I'm just curious, not implying lack of safety or whatever else. Why the wing is patched that way? I mean why the two small patches, the apparently missing a bit of the cover, and...why the leftmost patch is between other parts?


texts: How do I plan TOC/TOD in an IFR flight plan that includes SIDs and STARs?

texts:
For a checkride, I'm being asked to plan an IFR cross-country from Miami Executive (KTMB) to Tampa International (KTPA), using SIDs, STARs and approaches.

I'm going to use MIA5.MIA (Miami Five Departure) to depart KTMB, then get radar vectors to the WINCO transition, then fly via V97 to LBV (La-Belle VOR) and then use LBV.BRDGE8 STAR (LBV, ROGAN, BRDGE, JSTRM, PIE), and then get radar vectors to the Final Approach Course and perform the approach at KTPA.

My question is, when choosing the fixes for the flight log how should I include Top Of Climb (TOC) and Top of Descent (TOD)?

For the SID, which one of these options should I use:

1) Write KTMB, TOC, DHP, WINCO
2) Write KTMB, TOC1, DHP, TOC2, WINCO

Option #2 has two TOCs because the SID states that I should maintain 2,000 or assigned higher altitude, and then expect my filed altitude 10 minutes after departure.

And then on the STAR, where should I place the TOD: after the LBV VOR or after ROGAN? And what altitudes should I write after LBV if I don't get a descend via clearance?


texts: How can a two-engine B787 create three contrails?

texts:
Today I noticed overflying aircraft (over Sydney at FL400) which appeared to have three contrails. When I checked Flightradar24 app, I saw that this overflying aircraft is B787.
What would be the reason for three contrails with only two engines? Could the third be caused by APU, or just by a wake turbulence, or anything else?
I tried to take a photo using binoculars (sorry for the quality, I tried my best). And also a screenshot of the A/C from Flightradar24 app.


texts: Was the Airbus A300/A310 ever supplied with a yoke and not a sidestick?

texts:
In the Air Crash Investigation episode "Kid In The Cockpit," which details the crash of Aeroflot Flight 593, the video shows the plane had a yoke not a sidestick

I was under the impression all Airbus models, even the earlier ones, used a sidestick.

Can anybody clarify this for me?


texts: What is the diffference between landing lights, taxi lights and external lights?

texts:
A comment on this website along with an answer for the same question added confusion to my mind. Before reading this, I thought taxi lights and landing lights were the same, which seems to be true is some cases. I thought those lights were used for approach, taxiing, and take off and were strong lights designed to light the floor in front of the aircraft in the darkest night. Moreover, the answer linked above speaks of exterior lighting.

Now, I got a serie of questions to clarify the role of those "exterior lighting":

What are the difference between them (landing lights, taxi lights, other exterior lights I never heard of)?
What purpose do they serve and when are they used? (Perhaps it is the same question)
Are all aircrafts equipped with?


texts: Why Do General Aviation Aircraft Cost So Much?

texts:
Purchase price. Not total cost of ownership.

This Aviation Question inspired mine.

A quote From this article in Flying Magazine (Dated 2012):

  Cessna is holding the line on pricing, but the new models still aren’t cheap. The 180 hp 172S, referred to by Cessna as the 172-SP goes for \$307,500 the 160 hp 172R sells for \$274,900.

Many years ago I heard this generalization: "half the cost of an airplane is litigation." And sure, I understand you should not replace a control surface cable with one from Home Depot. But still, these prices are breathtaking.


texts: What is the reason why dihedrals are used when building a plane?

texts: How does dihedral affect flight characteristics of a plane? I know it increases stability, however is it the only reason why it is implemented? If so, aren’t there more effective methods to stabilize the plane?


texts: Closest RL Match for Fictional Helicopter Design?

texts:
Erm, not sure if this is the best place to post this but it seems like the best place to get a pretty straight answer thus far in my search.

So yeah, this helicopter is obviously from a cartoon – but I'm writing a story and I wanted to refer to it more specifically if possible, and also I'm just plain curious about what real rotorcraft(s) it was most likely based off of. And so far the entire rest of Google has not been much help. Plus, I've tried comparing some of the era models (i.e. 1960s, 1966-1968) I've found pics of on my own – but yeah, I am pretty clueless here. =(

Can anyone help? Thank you so very much for your time!

EDIT: I mentioned the year and I put the source in the pic description, but I'll reiterate both here. It's Michi/Trixie's helicopter from the Japanese anime Mach GoGoGo/Speed Racer 1966-1968.


texts: Is it possible to prevent plane accidents due to fuel explosion?

texts:
We know that most of the plane accidents and deaths result from the explosion of fuel tanks in the planes, like when two planes collide, or when the plane falls on the ground.

With the advent of technology, i wonder whether it is possible to prevent the fuel explosion.

Can this be done by evaporating the fuel in the planes just before the collision?
Or use a solid architecture encapsulating the fuel tanks in the planes, such that the fuel is not set to fire?

What research has been done in this field and if so what were the findings?


texts: What is the difference between microburst and windshear?

texts:
When I read about these weather phenomena, I find that both of them depict the same thing, and have the same actions to avoid. So why are they differentiated?

http://www.myairlineflight.com/windshear.html
https://en.wikipedia.org/wiki/Microburst


texts:
How much power do I need  for 3x3m wind tunnel,with airspeed up to 200km/h?
Some formula for calculation?


texts: Do military bases still employ wheel watchers?

texts: When I was in the air wing in the '70s, I had the unpleasant opportunity of pulling wheel watch. The unfortunate individual sat in a small shack (maybe 3 x 6 ft.) with a pair of high-powered binoculars ensuring that each and every aircraft on final had their gears down. If not, there were two flare guns pointed at opposite right angles to the runway that had to be fired to warn the pilot off. I know I had to use them on more than one occasion. I think it was a thirty-day hitch. It seems like such a primitive way to ensure the gears were down, and I wonder if it's still being used today?


texts:
From the FAA AIM:

  All 14 CFR Part 139 airports report declared distances for each runway. Other airports may also report declared distances for a runway if necessary to meet runway design standards or to indicate the presence of a clearway or stopway. Where reported, declared distances for each runway end are published in the Chart Supplement U.S. For runways without published declared distances, the declared distances may be assumed to be equal to the physical length of the runway unless there is a displaced landing threshold, in which case the Landing Distance Available (LDA) is shortened by the amount of the threshold displacement.

Can the clearway be located on a lake?


texts: Why is powering on the APU so low on the A320 emergency checklist?

texts:
In the movie Sully we have this section of dialogue

  He wasn't following proper procedure at all.
  And I know because I had the QRH in my hands.
  He switched on the APU immediately after
  engine blowback.
  According to the Airbus that's the 15th thing on the list to do. 15th!
  If he had followed the damn rules, we'd all be dead.

Now, another question discusses the importance of the APU to the crash, but my question is, why is it so far down the list? I suspect the above is dramatized somewhat, but it does seem odd that it's so low. What does Airbus consider more important in their handbook?


texts: In this picture, could anyone describe what type of aircraft and which airline it is?


texts: What type of aileron is the AIrbus A380 equipped with?

texts: The ailerons of the A380 seem to be in 2 pieces. What is its purpose?


texts: How is the center ILS used on the 747-400?

texts: The aircraft has 3 ILS receivers, but only ILS L and R in the CDUs. How does the ILS C is put into action?


texts: What kind of delay does the A320's fly-by-wire system add?

texts:
More precisely, I am wondering if there is any kind of data on how long it takes between moving the sidestick and observing a reaction on the ailerons or elevator. I know that the physical control surfaces take time to move and, thus, I am only wondering about the actual latency added by the fly-by-wire (FBW) system.

My naive assumption is that the A320 runs a fixed control loop with precise timings. So, every $n$ milliseconds it samples the sidestick, calculates the necessary control surface deflections and then sends that via some bus which runs at $m$ Hertz. So, on average there is an expected delay of $x$ milliseconds between input and the control surfaces starting to respond to the input.

Also, is the delay noticeable by pilots?


texts: Do contra-rotating props have worse tip vortices than single props?

texts:
As I understand it, blades from a propeller have their own tip vortices, because the blades produce lift via the same aerodynamic principles as wings. So they must have tip vortexes too.

So with contra-rotating props, e.g. the NK-12, do the tip vortices interfere with each other in a good or in a bad way? Is their nature somehow better than those from single props?


texts: Why is this 777 with doors and windows covered?

texts:
It's in the desert somewhere and it has its windows and landing gear and doors covered. Why is it that? Of course, it's not in service anymore...
Source


texts: When approaching a stall, is the first priority to apply power or lower nose?

texts:
I’ve always wondered. And I’d assume it’s the same regardless of aircraft? But when approaching a stall would the main priority be adding more power?

I ask because what if a crew was on final for landing and approached a stall, the rear end is dropping and the nose is rising. I feel like the flaps at their current position during landing, would only make matters worse? And applying power could make more lift with a poor angle of attack?

Would a crew lower the flaps in that situation, after applying more power and pushing the control columns forward?


texts: How do elevons work to roll a flying wing?

texts:
I have an RC Flying Wing that uses elevons for control.  To go up both elevons move upwards and the wing pitches up. Both go down and the wing pitches down. I’m OK with this.

However, if I want to roll right, looking from the rear of the wing, the left hand elevon goes down and the right hand one goes up.  I can see this when I fly it that it rolls right but don’t understand why?

If an upward pitch angle produces lift to go up, (like when the elevons act as elevators) then why doesn’t the right wing produce more lift and thus the wing roll left? Either a flap produces lift or doesn’t?


texts: Why do some aircraft have 4 nosewheel doors?

texts:
The A380 has 4 nose-wheel doors. Look:

Source: Airliners.net

Why does it have 4 nose-wheel doors?


texts: What are the airworthiness requirements for transport category hybrid airships?

texts:
According to section 1.2 of the Airship Design Criteria (FAA P-8110-2), the FAA limits the applicability of airship airworthiness requirements to aircraft "capable of achieving zero static heaviness during normal flight operations."

If that's the case, then under which FAR part are hybrid airships with buoyancy ratios less than 1 certified? Assuming transport category, would the FAA just use Part 25?


texts: Will a Secondary Surveillance Radar be affected by a 300m high wind turbine?

texts:
60 wind turbines are located at a distance of about 30 km away from a Secondary Surveillance Radar installation; what will be the impact of this?

My less than stellar knowledge of radar systems tells me that there shouldn't be an issue, since its a secondary radar and not a primary radar (the blades are big enough to be mistaken for an aircraft) which relies on reflection.

But the 30 km distances makes me doubt if this will actually be the case, might a 300m high obstacle in a radar's direct line of sight might cause problems?


texts: F-16: MAIN PWR ticking sound, what is it?

texts:
What is that sound that starts when MAIN PWR switch is turned on in the F-16? Its sorta like a fast ticking sound.
Why is it there, what makes it, when does it stop? And is it also there when only putting switch to BATT?

You can hear it here:


texts: Is commercial domestic service using foreign registry aircraft allowed in the USA?

texts: I recently saw a domestic tour operator using aircraft with foreign registry. The pilots had U.S. CPLs. Can foreign-registered aircraft operate commercially within the U.S.A, in an operation where flights begin and end within the U.S.A.?


texts: How does the UK declaration for FAA pilots work?

texts:
I came across http://publicapps.caa.co.uk/docs/33/SRG2140_Issue02_Enabled.pdf

This seems to suggest that an FAA PPL doesn't have to go through any exams / checkride / etc (other than the rudimentary "confirmation knowledge of Part FCL Air Law and ATC procedures") in order to be allowed to fly up to 28 calendar days per year in UK airspace.

Can anyone share additional details on how this process works, such as how long does it typically take to have the declaration verified, what costs (if any) are involved, whether this process has to be repeated every so often or is permanent, etc. ?


texts: Why was NWS shifted from green hydraulic to yellow hydraulic system in the A320?

texts: In older Airbus A320s, the NWS (nose wheel steering) was on the green hydraulic system and now it's on yellow. What's the reason for the change?


texts: Does North Korea's aircraft registration prefix allow for only 500 aircraft?

texts:
In the Wikipedia page about aircraft registration prefixes, we can see that North Korea has P-500 to P-999. Does that mean that it’s only allowed 500 planes? What happens when the registry is all used?
(Oddly enough, I visited that Wikipedia page after reading an article about Star Trek’s starship Enterprise, also on Wikipedia.)


texts: How do pilots maintain awareness of other airplanes during taxi?

texts:
If I compare taxiing of airplanes with, for example, driving cars, drivers in the latter case regularly check the positions of their cars relative to others by using the different available mirrors. However, that is not an option in airplanes.

Just thinking about all potential possibilities, I imagine that airplanes probably rely on the airport control tower for making decisions that require the knowledge of the relative positions of other airplanes. Also, collision–prevention devices provide part of that information.

My question is:

How are airplane pilots aware of other nearby planes during taxi? Do they need that information, or is not useful for them as instructions are sent by the control tower?


texts: How long does it take for an airline to establish a new international destination/route?

texts:
This post discusses the process of opening a new route. I wonder how long does it take for an airline to get permission to fly a new route. I am interested on this because, say an airline goes bust during the current covid-19 crisis. If another airline wants to fly a route that was previously flown by the busted company, it will take some time for that to happen. Naturally, conditions might be particularly different in the current situation but it would be interesting to know the length of the process in normal times.

This article says it might take "years to develop". Anyone with a more specific estimate?


texts: I know that there are bolts to connect the centre wing boxes of the fuselage and wings in large aircraft, but what are the methods of connecting the wings and fuselage of small aeroplanes? I’m mostly curious about spars that go from wingtip to wingtip.


texts: How does the Pratt & Whitney Canada PT6 differ from other turboprop engines?

texts: As far as I know, all turboprop engines have mechanical continuity between the engine and the propeller except for the Pratt & Whitney Canada PT6 family of engines. What is the correct term for the setup the PT6 uses to power the propellor and how does the PT6's design differ from other turboprop engines?


texts:
This is a follow up to my previous question What do numbers signify in airport codes?

In that case, I was asking why my local airport (Markham Airport) had a number in its code (CNU8). I later learned that the code was not really a code, but a Transport Canada Identifier.

This leads me to my question, Why do some airports not have ICAO codes? At my local airport, there is plenty of glider activity, and a flight school is also located there.

My main thoughts for the airport not having a code comes from the lack of an Air Traffic Control Tower. When declaring a landing, pilots have to do declare it on Traffic, which doesn't have a controller. It looks something like this (based on memory, I'm not a pilot but I hope to be one):

  Markham Traffic, Aircraft Papa Lima landing on the grass strip beside whatever runway

Am I correct in assuming that airports without ICAO codes don't have codes because of the lack of a control tower? Or is there other reasons for this?


texts: "Gross" and "net" planned runway length for the Haifa airport

texts:
My city's mayor was just boasting on how she'd gotten an approval for an airport runway of length "2100 m gross, 1900 m net length", and that this would be enough to connect the city - Haifa - to hubs all across Europe.

I'm not sure what she meant exactly, but I looked up some aircraft runway requirements, and found this, with no distinction between "gross" and "net" length. Now, some of the Boeing 737 models can fit the "net" length she mentioned, and so can Airbus A319's - but A320s or A321s fall right between the "net" and "gross" lengths.

So, my question is:

Is there such a thing as "gross" vs "net" runway length? If so, what counts into the gross but not the net? Clear space between the tarmac and the perimeter fence maybe?
Was the mayor making an empty boast or can the information about that runway be interpreted so that what she said is correct?


texts: How to decide the diameter of a propeller and number of propellers needed in a UAV I am designing?

texts: I want to design a turboprop aircraft. I know all the design parameters such as lift, thrust, weight etc at a given flight stage. I want to know what the size of the propeller should be.


texts: Does ATC use True Course or Ground Track?

texts:
Reading the practice questions for PAR, I came accross this

  ATC advises, "traffic 12 o`clock." This advisory is relative to your
  A) true course
  B) ground track
  C) magnetic heading

I was inclined to got for A) but isn't that the same as B)?
Neither are defined in PHAK glossary.


texts: Where is pure outside static air pressure indication on A320?

texts:
I'm looking for the indication of the outside static air pressure in the cockpit.
Where is it located? One of the ECAM pages?

Thanks!


texts: Calculating the maximum altitude of a drone

texts: Is there an equation to find the maximum altitude that a drone or quadcopter can fly to ?


texts: Is the ATC of the lower and upper areas of the Netherlands combined or segregated?

texts:
I am simulating the capacity of the Netherlands airspace by using the sector capacity. But I am wondering for different height, the capacity works for both or a single level.

Therefore, I want to know if the controller control lower and the controller control upper area are from same system or not. The question can be paraphrase as, would there be a controller control both flights for two areas simultaneously?

And if possible, are there any documents explain it?

The map below comes from AIS-Netherlands.


texts: Has the F-35 Lightning II overheating problem been resolved?

texts:
This is one of the sources explaining the F-35 overheating problem. Has this been resolved?

Are the constant problems, that are being reported about this type normal for an aircraft like this?


texts: Does empennage height above the main wing matter

texts: Am still in my preliminary design, am already wondering as to how high above the wing should the empennage (tip of vertical stab) be?


texts:
How much oxygen do commercial airliners carry? Is is enough for every seat to have a 20-30 minute supply, is it a percentage of total flight time (ie 10% of total flight time), or is there a compressor on board?

I would assume the goal of the pilots during depressurization would be to repressurize whether that be by simply lowering altitude or other means. Thus, I would assume (hope) there would be sufficient reserves of O2 to do one or the other.


texts: Why are my friends flying over Norway, Sweden and Denmark from Manchester to Vancouver?

texts:
I'll start off by letting you all know that I am 100% blind, so I won't be able to read a map.

My friend Hudson came over to Canada with her friends last year, September 1 or August 31, 2016.

She likes to check where she's at once in a while when flying. She said it was an Air Transat Airbus 330-200. She doesn't remember the flight number, but it was probably TSC-285 or TSC-255.

Anyway, when she flew from Manchester (EGCC) to Vancouver (CYVR), she said "(laughs), Ann was out like a light when we flew over the Scandinavian countries." How on earth does this work?  I may be blind, but I do know that Vancouver is southwest of Manchester, and the Scandinavian countries are northeast of Manchester.

My question is, why would they fly over Norway, Sweden and Denmark when that is the opposite way to Vancouver? I'd love for an explanation please.

Note:

If you explain the route i.e. "she went north over x, then headed west and flew over by y" that would help, though it's not a requirement.  It is guessing after all considering she may have taken off northeast or southeast from EGCC.


texts: Is air in the toilet isolated, to prevent seeping into the cabin?

texts:
This made the news few days ago:

  British Airways flight to Dubai forced to return to Heathrow due to 'smelly poo in toilet'

As can be seen at The Telegraph and The Independent.

Made me wonder: isn't it possible to recycle the air from the cabin and perhaps isolate the toilet? This could lead to a whole new series of chemical attacks on long flights.


texts: Why did some aircraft use hand-crank instead of gravity for alternate gear extension?

texts:
I wondered whether the final scene in The Memphis Belle where they hurry to extend the gear by hand crank (because their electric system failed) is realistic, but according to this answer the B-17 indeed used a hand crank for manual gear extension.

But why did it (and other aircraft of the era that used similar system) need to manually crank the gear all the way down rather than just pull a latch out and let gravity do the rest, like modern systems generally work?


texts: Why is the de-icing fluid sprayed on jets coloured orange?

texts:
On a cold night or if it's been snowing, jets are sprayed with orange de-icing fluid:

But why is it orange?

If it's to see where's been sprayed and where you've missed a bit, black would be the most contrasting colour on white; while yellowy-green is the strongest/most visible colour to the human eye; and blue is the least affected colour for colour-blind people.

Just curious as to why orange.


texts: Can I do a dual VOR check on the ground?

texts:
I know that the regs are ambiguous on the subject, but does anyone have a good argument as to why or why not you can do a dual VOR check on the ground if the VOR signal is good?

For my particular situation, I'm at KRDM which is about six miles from the DSD vortac. There is a clear line of sight to the station, but the airport is a couple hundred feet lower than the VOR.
Seems to me that a dual ground check would be fine since no flags are visible and the station can be identified, but I'm not sure.


texts: Why most military transport aircrafts use turboprop engines?

texts: What is the reason behind that most (or many) military transport aircraft use turboprop engines?


texts: Is the destination of a commercial flight important for the pilot?

texts:
As has been recently advertised (in here, here, here also), a recent British Airways flight from London City Airport destined for Düsseldorf mistakenly flew its passengers to Edinburgh instead.

I'm a layman in terms of aviation, but I (and I'm sure many more do) do see aviation as a strictly regulated area full of double-checks, double instruments (even 2 pilots!) to make sure an airplane is doing exactly what it's supposed to be doing.

Perhaps mine is a rather car-centric view, but I can't imagine starting the engine of the car without knowing clearly where I'm heading, which landmarks, roads (and so on) I'm supposed to pass by during the route.

TL;DR:

Must (or should) both pilots know where he airplane they are flying is going to? Or do they simply follow an approved flight path?


texts: What appears on EGT Gauge if the mixture is rich or lean?

texts:
I have some questions on interpreting Exhaust Gas Temperature (EGT) readings.  Can you give me some input on:

What appears on EGT Gauge if the mixture is lean or rich?
what is the normal range, high range, and low range for EGT?
What is the relationship between the EGT and rich or lean
mixture?


texts: How does the throttle position affect the speed of airflow to the engine?

texts: It is said that the less we open the throttle the slower is the speed in Venturi tube, thus less reduction in pressure and less fuel is being sucked from float chamber, however, actually if we reduce the area of the tube by closing throttle ,according to Bernoulli theorem, the speed of air in the same tube should increase, shouldn't it?


texts:
update: In order to make it easier to answer this question, use of "synthetic materials as a replacement for rubber circa 1969" in any aircraft might be good enough.

Michael Crichton's 1969 science fiction thriller The Andromeda Strain and the 1971 film of the same name ficticiously describe/depict a Phantom F-4 where a biological agent recovered from a satellite and subsequently mutated degrades and destroys rubber-like materials in the aircraft including the pilot's oxygen mask, and eventually the pilot as well.
In this clip from the film an expert at the site of the crash says:

There is no actual rubber on the phantom F-4 general. It’s all a synthetic plastic compound called “polychron”. It has some of the characteristics of human skin.

The spelling is in the computer-generated closed captions. I can find an insecticide Profenofos which is also called polycron, but nothing else.
Crichton is famous for meticulous technical research (generally) for his books, though they are still of course fiction.
Because of that, I'm wondering if the plot device of "polychron" replacing rubber in the F-4 has some basis in fact.
Question: Did the Phantom F-4 contain "polychron" or other synthetic materials as a replacement for rubber circa 1969?


texts: What is the correct procedure to deal with a TCAS RA during intercept?

texts: What is the correct procedure to follow if someone is intercepting you (or you are the F-16 driver intercepting someone else, for that matter) and you (or they, if you're the interceptor) get a TCAS RA in the middle of it all?  I'm thinking to cases like this situation where an interceptor may interpret the interceptee's TCAS-triggered maneuvers as signs of noncompliance with the intercept...yet the interceptor may not know just what prompted TCAS to issue the interceptee the RA, and the interceptee must comply lest it is an interloping third party on a collision course!


texts: What does it mean to "firewall" an aircraft engine?

texts: I (think) I understand what a firewall is (at least, in a single engine aircraft where the engine is at the front of the fuselage), but what does it mean "to firewall" an aircraft's engines, as described in this incident report: is it just applying full thrust? What is the connection with the physical firewall?


texts: Is there an STC for converting the Continental O-470-R to a fuel injected engine?

texts: Is there an STC for converting the Continental O-470-R to a fuel injected engine without making any other changes?


texts: Is an aborted landing considered an incident for the FAA?

texts:
I was a passenger on a commercial aircraft on final approach into Salt Lake City. As we desended to approximately 1000' the pilot suddenly gunned the engine, climbed and aborted the landing. He then explained that the landing was aborted as there was another aircraft on our runway.

Is this a reportable incident to the FAA?


texts: Why do the F/A-18 and the F-22 Raptor have horizontal stabilizer as well as canted rudders for pitch control?

texts: F/A-18, F-22 Raptor have a horizontal tailplane as well as canted rudders? Why can't the horizontal tailplane done away with (as in the F-117) and have only the ruddervators for pitch control?


texts: How do redundancies work in aircraft systems?

texts:
I've read about many aircraft systems having redundancies. For example, both Boeing's 787, and Airbus's A380 have a triple-redundant FCS. In this case, it makes sense to act upon the majority's decision. If all three components disagree, how is it decided which one wins? Is there any record of disagreement amongst redundant systems in airplanes?

The primary differences I have compared to the question about Airbus's control systems (How does the Airbus flight computer's voting system work?), is verification for non-deterministic systems, as well as optics for visibility. Given that the entire systems run in parallel up until the verification component (from sensor input, onwards), there will be some, obvious delta in their "decisions." -- Although, most of the time, this isn't perceivable, is there any visibility into what's going on with the FCS?


texts: Did B-17 gunners beat on the wings of other planes in their formation?

texts: I am certain my father, a B-17 pilot, told stories about his gunner having to beat on the wing of another plane in the formation with the tip of his gun to get the pilot to pull away and avoid a mid-air collision. Anyone have a similar story? Do you know which gunner?


texts: Why is the nose of the Mig-21 shaped so differently compared to other fighter aircraft?

texts:
If you look at this picture below, you will notice that the nose portion of the Mig-21 has a unique conical shape which is completely different from the nose of the F-16.

(Source)

(Source)

So what explains the conical design of the nose of the Mig-21?


texts: I'm reading all these reasons why consumer electronics can't be on during takeoffs and landings and one specific reference that is made over and over again is the sensitivity of the ILS equipment. I understand that isn't a Die Hard 2 scenario, but what about simply throwing random interference on those frequencies hoping to disrupt navigation? I know very little about RF or the power levels involved, but a generator inside a hotel room in or around the airport property sounds like a feasible scenario.


texts: Do helicopter rotor blades speed up and down during the rotation?

texts: Does the inertia force change the angular velocity due to increase-decrease in the radius when the blade travels up? Does this cause an excessive bending moment?


texts: Why are we still putting lead in our fuel?

texts:
Lead in gasoline for automobiles has been banned from nearly every corner of the world, with most bans dating from the nineties. Why are we still poisoning ourselves with lead in Avgas? I understand that Tetraethyllead (as it's apparently technically called) is an octane booster, but the Wikipedia article also mentions that advances in the production of high octane unleaded fuel have pretty much nullified that argument. There are more reasons of course, but none the automotive industry wasn't unable to overcome many decades ago. I know it's 'low-lead' with very little lead compared to 'traditional' gasoline, but the phase-out of leaded fuels in cars started back in the 1970s, so don't tell me that most aircraft are simply too old. Are aircraft engines so special compared to car engines, that they must get their fix of lead before they go flying?

It is also a fact that there are aircraft piston engines which do run perfectly fine on unleaded fuel, why is it that hardly any airport offers it? Even in cost-conscious and eco-friendly Europe, most airports offer only 100LL and Jet fuel.


texts: What's the reasoning for full-stop landings at night but touch-and-gos during the day for passenger currency?

texts:
FAR 61.57 says that you need to have completed three takeoffs and landings to a full stop in order to carry passengers at night. However, you only need three touch-and-gos in order to carry passengers during the day.

Why the difference?

Is there some rationale for this?  Are full-stop landings considered safer during the night?


texts: Can an aircraft get certified for different runway lengths through the FAA based on the amount of payload it is carrying during said takeoff?

texts: When certifying a new aircraft through the FAA, will they certify the AC for just one takeoff distance based on the max payload capacity, or can you get the AC certified for multiple runway lengths based on the amount of weight it is carrying at the time of takeoff?


texts: Why are the first sounds of an approaching enroute airliner low frequency, booming ones?

texts: Often I will hear an intermittent, low frequency, powerful, booming sound that resolves into that of an airliner flying enroute high (FL 300+) overhead. So the first sounds that an airliner flying overhead to be heard are those. Why? I assume it has to do with the atmospheric conditions and how sound waves of different frequencies propagate forward..


texts: What is turbulence, and how does it happen?

texts: I'm not a pilot, so I always wonder when I'm flying why does it happen... Is it because of bad weather, or something else?


texts: Rate of climb equations for jet + propeller aircraft

texts: For an aircraft with both jet and propeller, how do we calculate the maximum rate of climb? I know the equation of maximum rate of climb, velocity, and angle for propeller and jet, respectively. But I don't know how to mix the two set of equations together.


texts: Who can sign off the aircraft after completion of 100-Hour Inspection?

texts: Can the mechanic who performed 100-hour inspection sign off the aircraft?


texts: What are the equations of motions for parafoils?

texts:
I want to use the following equations so as to describe the motion of parafoil
$$\left[ {\begin{array}{*{20}{c}}{\dot x}\\{\dot y}\\{\dot z}\end{array}} \right] = {V_a}\left[ {\begin{array}{*{20}{c}}{\cos ({\gamma _a})cos({\chi _a})}\\{\cos ({\gamma _a})sin({\chi _a})}\\{ - sin({\gamma _a})}\end{array}} \right] + \left[ {\begin{array}{*{20}{c}}{{w_x}}\\{{w_y}}\\{{w_z}}\end{array}} \right],
$$
where ${\gamma _a}$ is a flight path angle, and ${\chi _a}$ is heading angle in horizontal plane.

$${\gamma _a} =  - arcsin \frac{{{V_{az}}}}{{{V_a}}}$$
and also

$${\gamma _a} =   arctan \frac{{{-1}}}{{{L/D}}}$$
The equations for lift force and drag force lool like these

$${\displaystyle L\,=\,{\tfrac {1}{2}}\,\rho \,V_{a}^{2}\,C_{L}\,A}$$
$${\displaystyle D\,=\,{\tfrac {1}{2}}\,\rho \,V_{a}^{2}\,C_{D}\,A}$$

according to paper https://lib.dr.iastate.edu/cgi/viewcontent.cgi?referer=https://www.google.ru/&httpsredir=1&article=1629&context=etd

But why the reference area $A$ and speed is similar for both cases? I think its projection should be rather smaller for drag force than for lift one.

But then on can make assumption that
$${\gamma _a} =   arctan \frac{{{-1}}}{{{C_{L}/C_{D}}}}$$
I don't understand why this is valid for parafoil

Anyway, I don't want to sink in rigid body physics and it will be comfortable for me to stay on next level of abstraction.

For my case the maximun lift-to-drag ration
$L/D = 4$ and the only information i know is the area of parafoil.
It's enough to characterize the simple model but i can't describe the change of speed caused by the change of lift-to-drag ratio due-to symmetric motion of control handles (breakes, srtopes? I'm not sure what defenition is correct). What is the equation that is responsible for the dependence of lift-to-drad ratio on symmetric motion of handles? Or is there other way to write down variation of velocty due-to handles lengths that allows not to consider forces? It would be appropriate if you know how it was done in X-38 parafoil.

In my opinion the shoud be the law like this
$${\gamma _a} = {\mathop{\rm artan}\nolimits} \left( {\frac{{ - 1}}{{L/D}}} \right) = f(\delta )$$ where $\delta$ is symmetric lenghth of each of two  control handles. But as I said I have only area of parafoil that is 400 ${m^2}$ and mass a few ton.


texts:
There are several Zero-G airplanes to experiment briefly microgravity without going into orbit. One is the A310 from Novespace (F-WNOV):

Novespace A310 F-WNOV (source: Jonas Wirz at Airplane-Pictures.net)

When a Zero-G flight is executed, fuel should take the form of a sphere in the tanks, like demonstrated in the cabin for a beverage.

Advertisement in microgravity (source)

Thoughts:

This effect won't appear in negative G, subject to the design, fuel lines may still be immersed in tanks, this cannot be the case in micro-gravity.
The 0G segment is likely flown with power. First this is not a continuously descending flight as seen below. Second, friction will slow down the free fall anyway and must be compensated by some acceleration from the engines.

0G segment is not limited to the descent (based on source)

How does Airbus ensure the fuel is still delivered to the engines at the required pressure, without air?

Related: Are engines fed differently in reduced gravity aircraft?

Basically it says no modification is required because the lines are pressurized, and this is supported by a 1966 Nasa study (Use of aircraft for zero-gravity environment) which is not more detailed. The line being pressurized downstream of the pumps seems only one element of an adequate design. Upstream fuel will experiment the effect of micro-gravity and lines are no more immersed in the fuel. Air can enter and create a problem when reaching a pump or an engine. Pumps could be drained. Maybe the problem won't appear during the 0G segment, but it should appear later.

I'd like to have the details about how pumps, pressure, flow, or anything else contribute to maintain a good fuel supply to the engines.

This is the fuel system for the A310:

(Source)


texts:
Why are engines with carburetors hard to start in cold weather?

And why is there a different procedure for hot start scenarios, after you've just shut down the engine and want to power up again?


texts: Can a US PPL holder log ASES time in Canada while flying with a local FI?

texts: I am an FAA PPL, and I'll be visiting Canada. I'd like to log some seaplane time while I'm there. Can I log ASES dual-received time with any Canadian instructor, or do they need to hold an FAA CFI certificate?


texts: How does an aircraft tailplane keep the aircraft stable, and prevent it from tipping over? Also, how does the lift generated by a tailplane compare to that generated by the wing?


texts: Is right rudder always needed during go-around/touch and go with a Diamond DA-40?

texts: Is application of right pedal always necessary in parallel with advancing power lever in diamond aircraft (DA-40) during go-around/touch and go?


texts: Why do high altitude air-launch plane designers choose to use two fuselages?

texts: We see double fuselages in both the huge Stratolaunch vehicle and in Virgin Galactics high altitude launch vehicle. What about this design makes it desirable?


texts: Why does a stall decrease lift, rather than increasing it?

texts:
A stall occurs when the angle of attack of a wing or other airfoil becomes so high that the airflow over the upper surface of the wing separates from the wing, rather than remaining attached to it; this causes the wing to produce less lift and more drag, making it harder to maintain level flight and more sluggish to respond to control inputs.

However, shouldn't the airflow separating from the wing's upper surface result in a large area of low pressure above the wing, and, thus, greatly increase lift?  What am I missing?


texts: For slow-flying ultralights, how would a delta wing compare to a biplane layout of equal wing area?

texts:
Context: By "slow-flying" I refer to ultralights that can be classed as  "motorfloaters" - similar wing loading to a hang-glider, stall speed below 40km/h, cruise speed not much above.

I'm interested in designing something of similar capabilities to M. Sandlin's Bloop ( http://m-sandlin.info/bloop/bloop.htm ) where the plan is to get into the air as cheaply as possible and then "fly too slowly/lightly to really be able to hurt yourself". (See also Ron Wheeler's Skyscout, more traditional ultralight design but manages an empty weight of 55kg, MTOW 135kg and a stalling speed of 32km/h, and and first flew in 1974 - http://all-aero.com/index.php/54-planes-p-q-e-r-s/9873-skycraft-scout- .)

The Bloop's designer chose a biplane layout as an easy way to achieve high wing area and structural strength for a given span, with cheap/light materials. The wings are approx 9m^2 each, with a span of 7.6m. (Due to diminishing aerodynamic returns on additional wings, I'm not sure whether to treat this as a total wing area of 18m^2m, or less - I have seen some sites suggest *1.5 instead of *2 as a good estimator.)

Given deltas also offer a large wing area and good structural strength, I am curious: Assuming similar wing construction - rigid metal frame, foam LE supports, stiff fabric covering - what differences in flight performance could be expected if an otherwise-similar craft flew with a single delta wing, of equal total area but lesser span? For example's sake, let's say a span of 5m.

Off the bat, I would expect induced drag to be much higher due to vastly lower aspect ratio, but I'm unsure to what degree that may be balanced by the removal of an extra wing's worth of profile drag, interference between the two wings, and parasite drag from struts and bracing wires etc. Plus, possible improvements in lift coefficient for same AoA range as I would think the wing would operate at much higher Reynolds numbers due to greater average chord length.


texts:
For cars, I've heard of LLumar used as window tint.
Do jet aircraft use window tint? If so, what type of window tint do they use?


texts: What improvements did Airbus make as a result of the Air France 447 accident?

texts:
As far as I can tell, the following factors all contributed to this crash:

Pitot tubes susceptible to ice crystal blockage
Crew not aware that they can stall the airplane due to alternate law
No return to normal law after reliable speed information was available to the flight computers
"Unlinked" sidesticks which allow the pilots to command different inputs, unaware of what the other pilot is commanding
Stall warning goes quiet when the airspeed is too low

Of these, the first factor (pitot tubes) was already in the process of being mitigated. What about the other factors though? Were the onboard systems modified in any way to fix these shortfalls?

I'm no expert but it seems like at the very least that the following would help:

If the stall warning didn't stop, but instead changed into an even more ominous "you're now tumbling down at less than 60 KIAS" warning.
Also, given how extremely rare alternate law appears to be, it might not be out of order for the airplane to announce that it is now very much possible to stall the plane by pulling up (in actual words).
Finally, it sounds like the unlinked nature of the sidesticks was a big part of the problem; are there good reasons to leave them unlinked in future designs?

Some context:

Wikipedia article about the crash
CVR transcript and comments


texts: Why does a clean configuration lead to the generation of greater wingtip vortices?

texts:
"Slow, heavy, clean" are the three major conditions generating stronger wing vortices. It's very clear how "slow and heavy" aircraft create stronger vortices, but why a "clean" configuration generates stronger wake turbulence is less clear.

I did some digging on this, and found some people saying "use of the flaps reduces the AoA and thus leads to weaker wake turbulence" and others claiming "use of flaps moves the center of lift toward the root of the wing and that leads to less lift around the tip of the wings and thus less wingtip turbulence.

Which explanation is correct?

Edit) I checked the answer given here What is the relationship between angle of attack and wake turbulence?, but I'm not really sure "not really" is the right answer to this. The AIM (Aeronautical Informational Manual) is very clear about this, designating "clear" (along with "heavy," and "slow") as one of the three factors that increase wake turbulence.


texts: What are the guidelines and regulations for building a helipad for multiple aircraft?

texts:
Are there any guidelines and regulations governing the ownership and construction of a multiple aircraft type helipad in

a) the USA
b) Europe?


texts:
On the FAA medical exam there is a conditions section and one of them is mental disorders. I have/had OCD so I have to check yes. I'm getting off my med soon and then I will have another exam, so that I don't have to check this element anymore.

I heard I could use a Special Issuance to get a medical certificate. How do I request this Special Issuance?

On the FAA website it says:

  The applicant must demonstrate to the satisfaction of the Federal Air
  Surgeon that the duties authorized by the class of medical certificate
  applied for can be performed without endangering public safety for the
  validity period of the Authorization. The Federal Air Surgeon may
  authorize a special medical flight test, practical test, or medical
  evaluation for this purpose.

My OCD is not and was never that severe, I never had depressive episodes. I have a flight simulator and I don't repeat actions or have to check over and over again, or make sure everything is perfect; My OCD wasn't like that.

Right now I'm in contact with leftseat.com. They say they can get me a medical certificate, but nothing in the document they gave me mentions meeting a Federal Air Surgeon. I'm just really confused, as I think I need to meet one for the Special Issuance.

Could someone clarify this?


texts: Can passengers tell (without GPS etc.) where the aircraft is heading to?

texts:
I was watching Mayday Varig Flight 254 and at minute 38 it said that some passengers noticed that the plane was flying in the wrong direction. This accident took place in 1989, so my question is: without 'modern' aids like GPS, smartphones, in-flight entertainment system maps etc., can a passenger really notice where the aircraft is heading to?

(I suggest you watch that minute of the video if you have the time. It will help to understand the question.)


texts: What are the circled features on the upper surface of the A380 wing?

texts: On the A380 wing are at least 3 red circle each side. There seems to be a black part inside. Is this a dip stick, or something else?


texts: How does thrust reversal work on a jet engine, and when should it be used?

texts:
A two part question this time, though they are closely related enough that I figured I'd knock them out all at once.  I figure the first question probably informs the second question anyway.

Firstly, how does a jet engine flip over to reverse thrust?  I'm assuming the turbine doesn't actually switch directions.  Is there a set of blades towards the rear of the engine that divert the flow forward again?  How's that work?

Probably more topically:  When is the right time to apply reverse thrust?  I'm assuming you ought to be on the ground (that seems like a given), but are there checks that a pilot has to do before engaging the reverse thrust?  Are there times when it's not used, or when it possibly just isn't necessary?


texts: How is the load & trimsheet form sent to ACARS?

texts:
After the last passengers and baggage are loaded onto the aircraft, the pilot in command is given a form called load & trimsheet which shows the passenger/baggage distributions, total weights and cg positions. The form can be prepared manually or by a computer program by the authorized ground staff. This form has the wet signature of the ground crew coordinating the flight and the pilot in command on it and these signatures ensure that the form is legal.

My question is about the process of sending this legal form to the cockpit of the aircraft via ACARS. When the form is transmitted to the aircraft via ACARS, is it still considered to be a legal document without wet signature on the form?
How is this process run by airlines?


texts: Why do we have to perform a full ADIRS alignment between latitudes of 2 degrees North and South on the A320 family?

texts:
In the latest FCOM revision under the preliminary cockpit preperation normal procedures chapter ADIRS alignment has been added. However most of the conditions remain the same except for a new line which has been added wherein a full ADIRS alignment has to be performed at airports where the latitude is within 2 degrees North and South.
Could anyone explain with a reference why Airbus has decided to add this ?
As per my company FCOM this is only applicable to certain MSNs (mainly our newest A320-251N's)


texts:
Last night, I had to change planes at LAX because the United Airlines B737 that I was flying on had radio problems and thus could not fly over the ocean. One of the hi-frequency radios had problems, and the pilot said that both radios must function in order for the plane to fly over the ocean. So I flew on another B737 and arrived at Honolulu almost two hours late.

Do airlines keep "spare" planes at major airports in case problems with planes that are scheduled to fly happen? What is the procedure for getting a replacement plane? A plane could not be flown in at a moment's notice, obviously, because it could take hours for it to arrive.


texts: What does the Airspeed indicator show when your pitot tube is blocked?

texts:
So the question in the topic.
I want to clarify whether the speed indications is maintained or go to 0.


texts:
Was the Wright Brothers' 1902 machine a working glider or just a kite?

I spent the last days reading the letters and articles of Amos I. Root, the man who claimed he had seen Wilbur Wright flying his plane in a circuit on September 20, 1904.

I had already been aware that the 1903-1905 powered flights of the Wright brothers could be a fraud but I was convinced, before reading the above mentioned book, that the 1902 machine was a true glider that could be flown in a stable manner for 600 feet.

From what I have found on the internet (see the two attached videos) it appears that the 1902 glider could be more a kite. I simply do not find videos with this apparatus in free flight for distances like 100-200 meters or even shorter.

Question: Have somebody built a replica, of the 1902 apparatus, that flew without being towed and kept stable by people on the ground?

The letters of Amos Root to the Wright brothers and his articles about them.
Click to download the book.

A replica of the 1902 Wright glider.
Click for the video.

A replica of the 1896 Chanute Herring glider.
Click for the video.

The 1896 Chanute-Herring machine is a real glider, as ca be see from the video. It does not fly long distances but its stability is remarkable.


texts: What is this sound from Airbus aircraft before take off?

texts: When flying in an Airbus, I often (if not always) hear a weird sound before the aircraft starts to accelerate for taking off. From where exactly does this sound come from? Why doesn't it appear on other aircraft?


texts: Could the autopilot have rectified the flight path without any crew input on the Aeroflot Flight 593?

texts:
In the case of the Aeroflot Flight 593 air crash, could the autopilot have rectified the flight path of the Airbus at any point if the crew had not attempted to correct the spin, even while partially disengaged as it was after the son applied to much force to the control column?

  Despite the struggles of both pilots to save the aircraft, it was later concluded that if they had just let go of the control column, the autopilot would have automatically taken action to prevent stalling, thus avoiding the accident.


texts: Where do airports use 3-bar VASI for the visual glideslope?

texts: What are some airports that have a 3-bar VASI system?  I am trying to find some locations to compare what the chart supplements say to the supplements for those with 2-bar VASI systems.


texts: Does "pendulum effect" apply to hang gliders or any aircraft?

texts:
In discussion of aircraft roll stability in FAA paragraph on dihedral effect and in keel effect and in Why are high wing aircraft more stable the question of pendulum effect arises.

This is usually described as center of gravity displaced laterally from below center of lift during a roll in a high wing airplane causing a rolling moment which restores wings to a level orientation.

source

In any explanation you give, please consider the case of a hang glider which depends on weight shifting to control roll and pitch. (Don't need to discuss pitch)

source


texts: Re old (1993) US VFR sectional charts-- when did the term "Class E" first appear?

texts:
When did the phrase "Class E" or "Class E airspace" first appear on the legend of US VFR sectional charts, to identify the meaning of the thin dashed magenta line?  I'd like to narrow down the date as precisely as possible. Currently I'm aware that this phrase DID appear on the legend of a sectional chart (Hawaiian Islands) effective November 11, 1993, and did NOT appear on the legend of a sectional chart effective August 19 1993.  Please post the "effective date" of any US VFR sectional chart that you are aware of before November 11 1993 in which the phrase "Class E" or "Class E airspace" does appear on the legend, or the "effective date" of any US VFR sectional chart that you aware of after August 19 1993 in which the phrase "Class E" or "Class E airspace" does not appear on the legend.

Basically this question is just asking when the current "alphabet" system of airspace classification first appeared on US VFR sectional charts-- presumably the terms "Class A", "Class B", "Class C", "Class D", and "Class E" were all introduced at the same time.

When answering this question please disregard any reference to foreign (e.g. Canadian) airspace on the legend of the US VFR sectional chart-- the transition to the "alphabet" system of airspace classification may not have been simultanous between the US and all bordering countries.


texts: Do (or can) pilots observe religious fasts when flying?

texts:
This question is about religious fasts like the Muslim Ramadan and others.

Is there a civil aviation regulation about this? Must a pilot eat and drink by the regulations (or abstain from flying), or is this an issue left to the pilot's personal decision?

Obviously if a flight takes long hours and the pilot can't eat and drink, or abstained from eat and drink for long hours before the flight, this can affect the pilot's performance. I don't know enough to say if it can actually impact safety but it is obvious that the claim would not be far fetched.

How is this issue addressed in airlines? For example in Muslim countries where I would expect a significant number of pilots to be Muslims, if a religious fast is widely observed this could be an issue.


texts: What is the difference between TAS and GS?

texts: I'm looking for an explanation of true airspeed and ground speed.


texts: What is different between a B737 and B757?

texts:
Both are single aisle, 3 by 3 seating planes.  Both are vaguely similar in length (with appropriate models).  But they have fairly different ranges.

For similar sized airplanes, why the big difference?


texts: RATO used to get civilian aircraft out of airports with inadequate runway length?

texts:
There are plenty of stories of large aircraft accidentally, or emergently, landing at airports that don't meet the plane's runway length requirements.  The only solution to getting them out that I've read is stripping them to the point that some authority deems them light enough for takeoff on the short runway.

What I haven't read of are the use of any measures to increase the thrust available for the takeoff run.  The first idea that came to mind was the use of RATO.  Is this possible with civilian aircraft?  Is it done?  If not, why not?

(My second thought was to temporarily install water injection.  But then I figured that by the time a system like that could be tested and approved the plane could have been disassembled for overland shipping.)


texts: How feasible is it to use Smart Materials on aircraft?

texts:
Smart or Shape-memory materials have been known for quite long. What factors/limitations are put on it for applications in aircraft?

For someone who doesn't know much about its material properties, it seems quite good to have deforming wing or other parts and seem to improve aircraft performance. (One example might be: suitable wing geometry deformation according to aircraft's speed regime)


texts: What is this aircraft that appeared at Oshkosh 2017?

texts: This photo is an image from a youtube video of Oshkosh 2017.


texts: How does the mounting surface flatness affect radio altimeter reading?

texts: It is recommended that the antennas be installed on flat surfaces. For some UAVs, the bottom of the fuselage is very narrow and sharply curved away from the antennas. How does it affect the measurement error?


texts: Why do I hear airplanes' engine sounds in the sky?

texts: I've been wondering all my life about an issue related to aviation. I see airplanes, large airplanes they look commercial in nature but I'm not sure, flying in the northern side of where I live and where the sea is located. I don't live next or near an airport, there's only one airport located far away from where I reside, about 20 or more Km. But I always hear airplanes flying, the sound of the engine is like the sound of thunder. Sometimes I hear the sound at night, sometimes I hear it at evening and I always ask myself, why do they fly here and at a very low altitude and the airport is just so far from my location? Though, I see the airplanes themselves, so I'm sure they're flying over the sea I guess.


texts: How do dry bays protect against fire, and do civil aircraft also have dry bays like military aircraft?


texts: Has anyone researched or built an aircraft that controls pitch and roll by pumping liquid within the airframe?

texts:
I am confident I have seen an article couple years ago about a "static surface aircraft" (or at least a concept of it) with no control surfaces, which uses a "wet mass" to adjust its roll and pitch.

The container within its CG is filled with a fluid which is then transferred (or sucked) to the wing tips (to control roll) and along the fuselage (to control pitch). I'm not sure about the yaw control - it should be elevon-like.

Having spent half a day online, I have been able to only find a DEMON UAV from BAE systems, a "flapless" aircraft which uses flow injection above the control surfaces for maneuvering. That is not the same.

My question - is there something fundamentally wrong with a concept I have described?
Were there any experimental aircraft made?


texts: Are ASR and PAR approaches commonly used in Europe?

texts: How common are ASR and PAR approaches these days? Are they still practiced anywhere in Europe?


texts: Why do some airport towers avoid monitoring 121.5?

texts:
In the USA airport facilities directory (AFD), some towers (eg KSJC) are listed with the note:

  Emerg frequency 121.5 not avbl at tower.

Why do these facilities not monitor guard? Does the note actually mean that they cannot even talk on 121.5 in an emergency?

I am assuming it is because a different facility in the area (eg a TRACON) is monitoring guard, and they don’t want two facilities taking responsibility for guard. But suppose an airplane is landing in an emergency, does that mean the tower couldn’t even listen to the emergency communications?

How does this work practically in emergencies?


texts: What's the relation between speed of an aircraft and takeoff distance?

texts:
I'm making a tool that when given : weight of aircraft , takeoff speed , runway length and some other parameters , it analysis the takeoff performance and states whether using the brakes now is safe or not . So I'm looking for a mathematical relation between the takeoff speed and the takeoff distance to use it in my code . Based on the given speed I want to determine whether the runway length will be enough or there will be a hazard . Is there any mathematical formula for calculating the takeoff distance using takeoff speed and weight ?? or how do people calculate that ? I need any method .
Any help is appreciated . Thanks


texts: In an Inertial Measurement Unit, how are the body-axis velocities calculated?

texts:
What are body-axis velocity components (u,v,w)? Are they calculated from IMU acceleration components (Ax,Ay,Az)?

How can this be related with the airspeed measured from the pitot tube?


texts: People in a rollercoaster or falling elevator feel the rapid descent, so why don't pilots in the cockpit?

texts:
Judging from the CVR transcript, the AF447 pilots didn't realize for most of the plunge that they were stalled and rapidly losing altitude.

Why don't pilots in the cockpit get the same sensation of falling down as people in a rollercoaster or a falling elevator ? Both are situations in which you would unmistakeably know you are falling. (If you have never experienced a rollercoaster descent, believe me, it's noticeable ;-). So why and how does it differ for the pilot in the cockpit ?


texts: How did aircraft communicate during early air travel?

texts:
During the initial era of air travel how do the pilots/Navigation officers would communicate with ground stations?

Do they use radio communication? Or Telegraph was used?


texts: Has any passenger airliner ever offered forward-facing windows?

texts:
The empty, dolphin-like, forehead of the A380 seems like it would be an amazing place for the first and/or business class bar, especially if it had forward-facing windows.

I realize in the A380's case there are crew rest and storage compartments in that space, but wondered if there have ever been any passenger planes outfitted with forward-facing windows to enjoy the view?

Image source: lufthansa.com


texts: In Polikarpov I-153, Were the gulled wings very important?

texts:
Lets look to the I153

It looks like it was made in order to make space for pilot to see its front just like here
But What about in the aerodynamics study ?
Are Gulled wing design very important in order to make wings farther away from each other ?
Also what would happen if it was straight just like  ?


texts: What's the difference between overrun and overshoot landings?

texts: Is there a difference between overrun and overshoot landings or are they exactly the same, talking about a runway excursion?


texts: Would there be an efficiency advantage to weighing passengers?

texts:
In order to estimate the total weights of aircraft I know that the dispatchers use average weights for adults / children etc.

But since this is an average I suppose there's a standard deviation and sufficient allowances must be kept for safety etc. i.e. Factors of safety since the estimation itself is imprecise.

Question: I am wondering how much would be the efficiency advantage (if any) if a commercial airline decided to have weighing scales at check in for exact weight determination of every PAX? By efficiency I mean if you knew the exact passenger weight, you wouldn't have to use as large a factor of safety (conceivably) and hence could accurately pack in more cargo in the holds.

Are any airlines actually doing this? Or is the benefit insignificant to justify the modification? I mean airlines do go pretty far to ensure they can carry max payload right?

Note that I'm not asking about charging PAX by weight. Just about exploiting your load capacity to the fullest by reducing estimation errors.

If not  during check in, is there a safety advantage to incorporating a scale in the jetbridge to track total weight going in? Just to guard against dispatcher errors?

Alternatively, what about load cells in the wheel suspension itself. That would not only give the pilot the accurate weights but the relative loads would also indirectly indicate the position of the CG?  Is that impractical or too expensive?

There's already a weight on wheels sensor, correct? How difficult would it be to convert it to a quantitative sensor calibrated for newtons?

This question was partially motivated by this related SE Aviation question :

How does a commercial airliner measure its weight/mass?


texts: What's the difference between positive and negative pressure relief valves?

texts: In cabin pressurisation systems, I thought that the negative relief valve is automatically opened if outside pressure becomes greater than inside pressure.


texts: Can spatial disorientation in low visibility situations lead a pilot to fly upside down?

texts:
In this comment it's mentioned that pilots in instrument conditions may wind up in a situation where they're inverted due to spatial disorientation, and be completely unaware of it until they fly out of the cloud.

Is that really something that can happen so easily?


texts: Does Airbus provide pitch control correction symbols outside "normal law"?

texts: Do pitch control correction symbols exist in 'alternate law' and in 'direct law' mode (if planes angle of attack exceeds dangerously)?


texts:
Wouldn't it be cheaper to replace black boxes by telemetry?

Seems that the costs of a single search mission for an underwater black box exceeds the cost of installing and maintaining telemetry sytem in an entire fleet of aircraft plus ground stations.

By telemetry I mean a system that broadcasts all the information instead of recording it in the black box. In case of a crash the data would be immediately available.

Wouldn't such a method have shed light on such misteries as the missing Singapur Airlines flight?

Of course, in very extreme cases where the telemetry system fails before the crash the black box would still be available as a backup.


texts:
From the pilot perspective I want to know how to deal with the noise in the cockpit on the turboprop aircraft while long-run flights.
The reason is old type aircraft with bad headphones which doesn't protect from noise than they should be.


texts: How to request to fly on a flight level, different from the direction, according to the charts?

texts: According to the direction, there are correct FL to fly, but due to weather, or traffic, the pilot would request a different FL, from the chart (according to the direction). Is there any correct phraseology to request it?


texts: How to calculate the best glide speed if there is none on the POH?

texts: I am studing the POH of Seneca II and could not find the Best Glide Speed. Where can I get this information from? I thought to multiply Vs clean for 1.4 to get an approximate result but I am not sure if this is the correct way to do so.


texts:
John T. Downey, who spent 20 years imprisoned in China, was captured when his plane was shot down during an attempted "snatch pickup". The spy they were supposed to retrieve had been turned by the Chinese, and they were waiting for the plane with anti-aircraft weaponry. This 1951 attempt was the first time the snatch pickup was tried in a war, according to this article about John T. Downey:

  The snatch pickup was a bizarre maneuver, and an untested one. The
  process called for an aircraft flying at low altitude to hook a line
  elevated between two poles. Connected to the line would be a harness,
  into which an agent would be strapped. The contraption resembled a
  swingset, if that swingset was designed to be born aloft by a cargo
  plane. Two men in the back of the plane would operate a pulley,
  dropping the hook intended to catch the agent and then reeling in the
  line; both the operators and the pilots required extensive training.
  Describing the operation in his 1984 book Perilous Missions, a history
  of CIA covert operations in Asia, William M. Leary writes that the
  agent was forced to sit impassively in his harness, awaiting possible
  decapitation, among a litany of other potential injuries. The pickup
  of Downey’s courier would be the first time the CIA ever carried the
  plan into action. The Air Force deemed the operation too risky to try.

Whatever happened to this technique? Is it used today?


texts: Is it allowed and/or safe to place objects on the dash in a PA28?

texts:
I am told by my maintenance engineer that NOTHING is to be put on the dashboard area above the instrument panel - this is where I keep my DUAL GPS to have an unobstructed view of the sky. It was asserted that it could block one of the vacuum vents that are on the top of the dash.

I follow rules to the 'T' but similarly to make up rules 'on the go' is also not appropriate - I could not find a single word about this in the POH?

Can someone tell me if it's allowed and/or safe to place objects there?


texts: Would plain and slotted flaps increase lift substantially in a distributed propulsion application?

texts:
Would plain and slotted flaps increase lift substantially in a distributed propulsion application for a slow moving aircraft (15mph)?
I understand that:

A classic NACA foil without flaps such as the NACA 650-18, as used on Zenith 701 STOL aircraft produces a maximum lift coefficient (Clmax) of approx. 1.5.

Add a plain non-slotted flap, and the Clmax increases to roughly 2.2.

Add slotted flaps, and the Clmax increases to roughly 2.8.

The maximum Clmax of distributed propulsion is 12.

Given a GA aircraft such as the Zenith 701, with an engine of 100HP, with a stall speed of 45mph, means the entire wing is bathed in air travelling at 45mph when flying at 45mph.

Assume the same given aircraft now has multiple propellers installed along it's entire leading edge in a distributed propulsion arrangement, with multiple engines totalling the same total Hp, flying at roughly 15mph and with an propeller exit speed of 45mph. This also means the entire wing is bathed in air travelling at 45mph. ( assume 100% efficiency, no swirl angle, etc.).

See graph below.
(Solid black graph - Source: Aviationchief.com. Added graphics estimated by the OP.)

As distributed propulsion is just "extra air", and flaps move the lift slope curve up and to the left, I would think the wing would see substantial increase in Clmax if plain flaps or slotted flaps added.

I understand that in distributed propulsion, a wing with a Clmax of 6, on a slow flying aircraft, (15mph), but prop exit speed 300% faster at 45mph, the local AoA would always be under 10 deg.

I would think there would be a substantial increase in lift when using a plain flap and even more when using a slotted flap, but almost no increase in Clmax above 10 deg AOA.

Is this correct thinking?


texts: How to determine the number of compression stages given a compression ratio?

texts:
I have a personal project to design a gas turbine engine, the main problem that puzzles me is how do I determine the pressure rise in each stage of an axial compressor?
Say, I'm planning on a 38:1 engine so how do I determine how many stages I might need and how much will be the pressure rise?


texts: Why do some helicopters have wheels instead of skids?

texts:
I have noticed that Black Hawk helicopters have tires, but I have not seen one take off like a plane.

When would a helicopter need to use a running take off or landing?
When is it determined whether a helicopter gets skids or wheels?


texts:
Whilst flying into London's Stanstead Airport the other day I noticed that despite there being many jetways available Ryanair weren't using them for any of their planes. Instead, they'd chosen to have pairs of staircases at either end of the plane. The same is also true when they are operating out of other airports where jetways are available.

Is this just done for speed or might there be other reasons for making this decision?


texts: Do landing gear doors need repairs after a gear gravity deploy landing?

texts:
I know that landing gears can be deployed even without hydraulic power by letting them go down by gravity, as seen on this video:

I was wondering: do the landing doors need replacement after the landing? It looks like the get damaged a lot, especially on hard touch downs.


texts: How can I get flight destination from ADS-B?

texts: If I have aircraft details such as the callsign, transponder code, and ads-b info, how can I look up the departure and arrival airdrome? Is there an API to obtain this information in a programmatic way? How does flightradar24, for example, obtain this data?


texts: How do thrust reversers in high-bypass turbofan engines counteract initial thrust?

texts:
I've been searching the internet for awhile and haven't really come across a good answer for this question. So:

I have a basic understanding of the principles of flight (thrust, lift, drag, etc). But one thing that has been confusing me is how exactly a thrust reverser on a high-bypass turbofan engine works. So from what I understand, the large fans at the front of the engine will provide the majority of the thrust. Air coming through the inlet nozzle produces an action-reaction pair on the fan blades to produce this forward thrust. So upon deploying the thrust reversers, the air that has already produced a forward thrust on the fan blades now moves back through the bypass duct to strike the thrust reverser, thus redirecting the air forward by creating another action-reaction pair to slow the aircraft.

So it just kind of seems to me that the thrust reverser just cancels out the thrust from the fan blades. Or is the air coming off the fan blades is accelerated so that by the time it hits the thrust reverser the forward directed thrust is greater than the thrust generated from the fan blades, thus producing a net reverse thrust?

Or maybe I'm just looking at this wrong and need to think of the entire engine as a closed system so that the air pushed backward from the fan doesn't produce an action-reaction pair (and thus thrust) until it exits the engine?

I'm just kind of confused on the specifics of the physics of the thrust reverser (where the action-reaction acts).


texts:
There has been a remarkable story this week of a Challenger 604 business jet being rolled after encountering the wake turbulence of an A380.

A Challenger 604 at FL340 operating from Male-Abu Dhabi passed an A380 opposite direction at FL350, one thousand feet above, about 630nm southeast of Muscat, Oman, over the Arabian Sea.
A short time later (1-2 minutes) the aircraft encountered wake turbulence sending the aircraft into an uncontrolled roll, turning the aircraft around at least 3 times (possibly even 5 times), both engines flamed out, the aircraft lost about 10,000 feet until the crew was able to recover the aircraft, restart the engines and divert to Muscat. The aircraft received damage beyond repair due to the G-forces, and was written off.

I subsequently discovered that wake turbulence sinks; according to Wikipedia:

At altitude, vortices sink at a rate of 90 to 150 metres per minute and stabilize about 150 to 270 metres below the flight level of the generating aircraft.

Well, now I know where not to fly my business jet...
Incorrect assumption
(See accepted answer below)
Presumably the vortices sink because they are denser than the air they were whipped up out of, but it's not clear to me why they are denser.


texts: Mach Factor - Factor increase of thrust due to the ram effect

texts:
In the book of Corke, Chapter 7 about engine selection, he speaks about the Mach factor which is a factor larger than 1 in supersonic to take into account the ram effect.

In his case study he takes 2,39 for a cruise speed of Mach 2.1.

He mentions that there exists algorithms and books that allow to compute this Mach factor.

I am looking for a figure showing this Mach factor in function of the Mach number. I have been looking like crazy.

If anyone has sources or this type of chart, it would be great.

Thanks


texts: How do I have to fold a emergency slide so it can be reused?

texts: I have the opportunity to buy a never used emergency slide from an Airbus A320 for cheap. So I need to know how they can be reused and how to deflate and repack them so I can use it for another time.


texts:
To find the velocity of the air flow at each section of the aerofoil, am I right to say that the horizonatal velocity of the air flow is constant throughout the chord while the vertical component of the velocity varies along the chord depending on the angle of chord w.r.t. horizontal?

So velocity at first plane is $\frac{U}{cos\beta}$?

If that is the case, will shifting the air upwards, not push the wing down? Or am I right to say that as the airflow around the wings, there is no net upward motion of air, thus it does not push the wing downwards?


texts: What does "ENG 2 REV PRESSURIZED" ECAM message mean in the Airbus A32F?

texts:
What does "ENG 2 REV PRESSURIZED" ECAM message mean in the A32F (Airbus A320 Freighter)?

What are the possible consequences and actions the crew should take, on ground and during the flight?


texts: Has the cause of the engine failure of Cessna's 182JT-A been determined?

texts: Last August during a certification flight, a Cessna 182JT-A compression-ignition (diesel) engine failed in flight. I've been Googling to find the cause of the failure and the status of the certification process but have failed to find any recent info. Does anyone know what the current findings have been and how Cessna expects to proceed?


texts: Can a holding pattern be in class G airspace?

texts:
Is separation provided between aircraft holding in class G airspace?
Could there be a holding stack in class G?


texts: How is the airspeed-Mach number transition handled in modern airliners?

texts:
During the climb phase, how is the transition from constant speed (IAS) to constant Mach number handled? Does the pilot flying have to manually "push the button" on the control panel, or is the transition automatically done by the aircraft? How does the pilot / aircraft know when the transition should happen (i.e., from flight plan?)

I guess it's the same during descent?


texts: Could a helicopter perform a forward inversion (front flip)?

texts:
This is inspired by a previous question

What would happen if I bank a helicopter then pull hard on the cyclic?

I've seen some pretty radical videos of piloting by Chuck Aaron, but I've not seen a helicopter perform a forward inversion (either by a flip or an inverted loop).  I've seen helicopters invert backwards and perform rolls, but not in the forward axis.

Would such a manoeuvre be possible?


texts: How close is the air resistance or drag force to being proportional to the airspeed squared?

texts: How is the total air resistance force exerted upon a body (aircraft or car) related to its speed relative to air at far away? A simple Newton's force momentum analysis suggests that the force $F \propto v^2$ where $v$ is the speed of the body. I am sure it is not exactly speed squared but how close is it for a car?


texts: What is the distance at which my VHF communication radio can reach ATC?

texts: I just installed 2 new TKM MX11 radios and a new Garmin 340 audio panel. I also put in new coax cable and 2 new antennas in my 1964 Skylane.  What kind of distance from ATC should I expect at 4 or 5 thousand feet?


texts: Which timezone do airspaces that cross a time zone boundary belong to on a VFR sectional?

texts:
The Albuquerque VFR sectional claims that the airspace table in the margin use local time, but some of the airspaces in the table cross timezone boundaries. Which  timezone do those airspaces belong to?

BRONCO 3 MOA is an example that crosses the New Mexico-Texas border and therefore from Mountain to Central Time:

See this excerpt from the margin which states that local times are used and lists the effective times for the Bronco 3 MOA:

So, in the case of the Bronco 3, are the listed "local" times MST/MDT or CST/CDT?


texts: How are performance variables accounted for when testing solar-powered aircraft?

texts:
With so many factors that could affect performance (wind, visibility range (amount of light), angle of the sun, etc.), how do they accurately test solar aircraft flight time? Any tips for doing my own experiment for a small solar RC plane (vs non-solar of same type)?

Thanks for any help!


texts: Why is a centrifugal compressor in aircraft engine less susceptible to stall and surge?

texts:
I have came across a similar question here. Although the answer doesn't explain much about why and is somewhat vague. I have read that centrifugal compressor can achieve a higher pressure rise per stage than axial compressor. So technically they are less susceptible to stall and surge.

How is a stall and surge occurring in a centrifugal compressor different from that occurring in axial compressor. What are the scenarios under which a centrifugal compressor stall and/or surge (Is it same as those scenarios in axial compressor. If so I do have a rough idea)? And where does stall/surge first occur in a centrifugal compressor (impeller or diffuser)?

Is it because the rotor blades of centrifugal compressors doesn't act/function like airfoils?


texts:
I've been told before that the runways for large commercial aircraft have to be built to withstand a large amount of force.  But I'm wondering exactly how much it is?  When a 747 touches down, how much force is being imparted from the wheels to the tarmac?  And, further, how much force is imparted into the runway while the plan is braking right after touchdown?

Bonus Points:

How much weight does the gear + the wheels absorb and dissipate?
I'm sure there's a range from a "greaser" landing with light braking all the way to whatever the highest the main gear is rated for, it would be nice to know both extremes and the mean.


texts:
What are aerodynamics benefits of using unloaded wingtips (zero lift)? does unloaded wingtip make inner parts of wing more efficient?
(I know that unloaded wingtip reduces bending moment,so structural weight can be  lower, thus reduction in L/D and higher net wing lift (lift minus wing weight), but you can connect wingtip with wire and use elliptical distribution..so..)