texts: Was flying a helicopter below building height against FAA regulations?

texts:
I'm referring to this incident: https://twitter.com/Dacheslow/status/1267638389421072384

Some people were saying it was illegal under FAA rules to fly that low and close to a crowd, and also to use a medical-designated helicopter to carry out police activity. Can anyone weigh in?


texts: Black boxes: great for crashes on land. How about additional "floaties" for water crashes (low-tech, light, cheap)

texts:
Without getting into the mess of redesigning existing Flight Data Recorders, I have a simple proposal that I think would help in deep water crashes.

I propose that several floating cushion sets be distributed around the plane (tail section, along fuselage, etc.). These FDR floaties would be about the size of a seat cushion, but they'd be wrapped in a water soluble cover. When a plane crashes into the water, if the plane breaks up, then several of the cushions would float to the surface. When the cover dissolves, several folded arms open up making it much bigger exposing a orange-nylon covered mesh with an aluminum sheet embedded. This would be easier than seat cushions to see from satellites and planes, and the aluminum layer would reflect radar and make it easier to find.

This alone would help find water crashes sooner, but if you add a simple USB memory stick in the center, then have data similar to the current FDR's being fed into it, then finding one of the floaties would give quite a bit of information including the final GPS coordinates before the crash.

These devices would be light and cheap. I'd think current planes could be retrofitted very cheaply. The only challenge would be the wiring needed to connect to the main FDR or the nearby data splitter. But just putting a few in the tail section alone would end this madness of having to find FDR's on the seabed to get a better idea of what happened.

Wouldn't this be easy to implement without disturbing current FDR use and development? These would be destroyed in a fiery land crash, but that is not their purpose. This is just so we can find plane crashes in the sea when we don't know precisely where they went down (and to get basic data when the black boxes are too deep to get to immediately). Malaysian flight 370 and Air France Flight 447 would have both been greatly aided if these floaties were in those planes. What do you think?


texts: Does the responsibility for the plane shift from the PIC, if they leave the plane?

texts:
Is the PIC still responsible for everything when they leave the plane and a co-pilot is staying on board? Are there differences between operational reasons for leaving the plane (doing the walk-around) vs private ones (going to grab a snack in the airport during a layover)? Does the PIC have to specify someone to be responsible for the plane while they’re gone?

If there is no international rule but airlines have rules in their SOP, what are those rules generally?


texts: Do the operations practices of low-cost airlines represent an increased safety risk?

texts:
Low-cost airlines spend less money on their operations. In most (not all, clearly) contexts of life and business, more money spent on the same kind of thing means a higher quality product or service.

Do any of the cost-saving measures adopted by low-cost airlines lower the quality of their operations (flight operations, aircraft maintenance, crew training, crew quality) in a way that could affect safety?


texts: What are the RVSM Critical Area markings?

texts: I couldn't find any image to show you what I'm talking about but on many aircraft there are markings around the static ports and the pitot probes that say RVSM Critical Area. What is this?


texts: Can pilots hear their passengers clapping on touchdown?

texts:
Something that just popped into my head: I've been on a few easyJet and Ryanair flights where a lot of passengers clap and cheer on touchdown. Would the pilots be able to hear this?

Here's an example I found by searching YouTube:

It seems pretty commonplace... but can the pilots hear them? I guess it would be distracting.

Just something I was wondering!


texts: How do I choose the correct airfoil for my UAV project?

texts: I am not able to decide which airfoil to choose for my UAV project as I am confused. I need to lift at least 10kg of extra payload excluding the weight of the fuselage. I can afford a wingspan of 3m with a cruising speed of at least 70kmph. Also I would like to know if there is any software or application to decide the airfoil for me?


texts: Is the Tower (Local) Controller responsible for "separating" VFR traffic in the pattern in the U.S. in Class D airspace?

texts:
For example, in U.S. Class D airspace, if an inbound aircraft operating VFR is instructed by the Control Tower to "enter left downwind for runway 18, report entering downwind,"  is the controller  responsible for providing specific separation between that aircraft and other VFR traffic in the pattern (not on the runway or taxiway)?

If the controller instructs an aircraft on downwind to "turn base leg now, (VFR) traffic is on a 4 mile final on a straight in." Is the controller now responsible for the separation?

I realize these are two questions, but they are related.


texts: How does helicopter mustering make financial sense?

texts:
I've seen and know that helicopter mustering is popular in Australia and what I do not understand is why this works from a business perspective.
Helicopters are expensive and dangerous machines so it does not seem cost effective to round up cattle and livestock when it could be done, not as quickly, by people on the ground with ATVs and other wheeled vehicles. Not to mention the low-level flying is very demanding and tough on the machines and maintenance.
Surely it would be cheaper to employ extra people than pay the expensive hourly rate of a helicopter?


texts: Trying to identify an aircraft from a photo

texts: I'd like to know if anyone can identify an aircraft from this photo. The man in the photo is my grandfather Joseph White. He didn't talk about what he did in the war and we have been trying to put the pieces together for years. Any assistance would be appreciated. This plane might have been captured so it's a larger pool of aircraft than I would be aware of.


texts: How do I calculate the air pressure on the maximum bulge of the airfoil?

texts:
Picture 2: source.

Consider I have an airplane and it wing, of course. The cross-section of the airfoil is as the picture 1. The leading edge and the wind direction are depicted there. The leading edge I depicted as simple as possible to make it easy to be understood. It is exactly a half of a circle. For clearer, you may see the second picture or watch the video of the link I provided above.

Then my question is, how do I calculate the air pressure in the leading edge's top bulge as in the first picture?


texts:
I'm sure many of you are familiar with "rudder hardover", where an aeroplane's rudder deflects to an extreme position - full left or full right. Many of you will be aware that such an event, caused by a faulty Power Control Unit, was implicated in the loss of United Airlines Flight 585 and USAir Flight 427. A rudder hardover was also involved in an incident on Eastwind Airlines Flight 517 and the investigation into that incident unravelled the mysteries around the loss of the two aforementioned flights.

My question is about the effects of a rudder hardover on flight - and how it led to the two crashes. I'm interested in what happens, aerodynamically, after the rudder has moved to its extreme position and the sequence of events which follows. It's obvious to me that a rudder hardover must be an extremely destabilising event. But I'd like a more detailed explanation of precisely what happens. What effects does it cause? What happens to the affected aeroplane and why might it crash?


texts: Could future airplanes use rockets to recover plane and/or prevent crash landings?

texts:
With the advanced rocket technology that SpaceX uses in the Falcon for re-entry and controlled descent, could the same technology be used in commercial aircraft? I'm asking about using it in emergencies like engine failures, stalls, loss of pitch control etc. in order to prevent a crash, or at least minimize the damage and reduce the fatality rate.

For fuel storage, the rockets could burn what's available in the tank without any need for an auxiliary tank dedicated to them.

I know that there is a similar technology used in the military: the C-130 Rocket Assisted Takeoff (JATO). But it's only used for short runway landings and take-offs.

EDIT:

The question is specific to thrusters that could recover the airplane from  unrecoverable situations (dive, bank, upside down,...). Question Why are movable rocket thrusters not used in airplanes? answer is generic and not detailed for such use case.


texts: Why are different distances listed for the ILS and the LOC on this approach chart?

texts: Maybe someone has an idea why are there two separate distance values (marked in blue) for ILS and LOC approaches?


texts: Does FAA recommends specific maneuvers for complex endorsements?

texts:
I was pretty excited for a 5 hour flight in a piper arrow in a new school this coming weekend but my instructor that I have not flown with before texted me saying that he will not sign me off after one flight and would like to narrow down the time to 2 hours only. Although I was not expecting to get signed off after one flight, I canceled the flight as I didn't want to fly with an instructor with a definitive mindset of not signing off. I would have liked to fly with an instructor who'd judge me based on my performance and learning capability during the flight and ground training and then decides whether to endorse me or recommend further training. Not only I have had bad experience with one of my "time builder" instructor as a student pilot, I have heard from other pilots that some instructors can give us hard time and not be fair.

So I wanted to ask two questions.

Is there a FAA recommended list of maneuvers/training material for each endorsement? So that if a student fulfills all the requirements and fly all the maneuvers safely, he'd get endorsed?
How do we keep instructors/DPE in check? Obviously they are experienced and safer pilots but it is quite possible that in one out of hundred scenarios they are wrong and pilots receiving training are right?


texts: Who does air traffic control to the oceanic flights?

texts:
ARTCC does air traffic control to the flights in their FIR. Then who does air traffic control to flights that are above the ocean(like pacific ocean or atlantic ocean)?
Is there any FIR above the ocean too?
I want to know that what facility does air traffic control to the flights above the ocean.
Please let me know in detail. Thank you.


texts: Could adding a gearbox to the Trent 900 improve the efficiency of the A380?

texts: Could adding a gearbox to the Trent 900 improve the efficiency of the A380 so that it performs better than a smaller jet, i.e with economies of scale? Is the absence of a gearbox in the Trent 900 the main impediment to the efficiency of the A380?


texts: How do viscous drag and form drag individually change as a function of angle of attack?

texts:
Typically, when dealing with airfoils, the drag coefficient $C_d$ is given as a function of angle of attack. If we limit the discussion to 2D subsonic incompressible flows, then the drag is the sum of the viscous drag and the form drag (pressure drag), equivalently:
$$C_d = C_{d,\text{visc}} + C_{d_,\text{form}}$$
Where: $C_{d,\text{visc}}$ is the viscous drag coefficient, and $C_{d_,\text{form}}$ is the form drag coefficient.
I've never seen, these coefficient plotted as function of angle of attack individually. That is, $C_{d,\text{visc}}=f(\alpha)$, or $C_{d_,\text{form}} = f(\alpha)$.
The reason I want to see them plotted individually, is to emphasize the contribution of each type of drag (qualitatively, I know that for angles of attack below stall, the viscous drag is higher than form drag, but for angles beyond the stall, (boundary layer separation), the form drag dominates).
Are there any graphs showing these coefficients individually, say for NACA airfoils?


texts: What to do when moisture forms on the helicopter's canopy in a weather front?

texts: Moisture has condensed on the canopy of your helicopter as you fly through a weather front – what should you do?


texts: What does 'laterally aligned' mean in this description?

texts:
In the Airplane Flying Handbook there is a section on crosswind takeoffs that mostly makes sense. However, this paragraph confuses me.

  Takeoff Roll

  As the forward speed of the airplane increases, the pilot should only
  apply enough aileron pressure to keep the airplane laterally aligned
  with the runway centerline. The rudders keep the airplane pointed
  parallel with the runway centerline, while the ailerons keep the
  airplane laterally aligned with the centerline.

Laterally is an adverb meaning 'Relating to the direction to the side.'

Later on they use this image which shows the lateral axis.

When I take off in a crosswind in an airplane with nose-wheel steering the rudder pedals are used to keep the plane on the centerline. The ailerons are deflected into the wind to keep the windward wing from rising.

So what do they mean when they say that “the pilot should only apply enough aileron pressure to keep the airplane laterally aligned with the runway centerline”?

Edit: I don’t think they are referring to keeping the wings level as some commenters say. This image from the same section somewhat exaggerates the effect but ailerons are used to keep the upwind wing down.


texts: What kind of insulation is used on commercial aircraft?

texts: How are commercial aircraft insulated and what kind of fire barrier material is being used?  How much insulation is required in a typical Boeing 747 vs. a Boeing 787?


texts: Why is the coefficient of drag for straight wings at supersonic speeds lower than for swept wings?

texts: Why is the coefficient of drag of a straight wing lower than the coefficient of drag of a swept back wing at higher supersonic speeds (above, say, Mach 2)?


texts: What restrictions are there for flying near urban areas in the United States?

texts:
Say you've got your own plane and take off and land from the same airport.
Weather is good, fuel is good, etc...
What would be the restrictions for flying near urban places like a city in the United States?

I live near a bunch of sea-planes that take off and land from lakes encircled by high-rises. Never thought about it till now, but how is that and other private flying entities like news choppers and ad-banner planes governed?


texts: How does the Airbus flight computer's voting system work?

texts:
From what I've read about Airbus planes is that their fly-by-wire system works by having three different flight control computers calculate what the plane should be doing and then vote on all the three outcomes about which to take. I would hope that they all give the same result all of the time, but as I understand it this is used to make sure that decisions based on faulty data doesn't scatter the plane across the ground. How does this actually work? How does the computer vote which result is the correct one, is it just a majority vote? What happens when all three outcomes disagree?

Also, is this system only in place when operating in normal law? And are they actually different software implementations or is the only difference that they are fed input from different redundant sensors?


texts: How can you fly your own military jet in terms of altitude and acrobatics?

texts:
So I know that you can legally buy and fly a military jet like the Mig-29 and the SU-27 https://www.wired.com/2010/01/own-the-coolest-jet-on-your-block/ and https://www.thedrive.com/the-war-zone/29292/you-can-buy-paul-allens-mig-29-fulcrum-jet-fighter. But practically can you fly it? I mean how high can you climb? How fast can you go (I know no supersonic flights are allowed above land, but what about sea)? Can you do barrel rolls and pull Gs? Also, can you use it to fly internationally (assuming that you can attach external fuel tanks in the first place)? Can you actually have fun with it lol?
Assume that money is no issue.


texts: What are those thin magenta lines on the Sectional / Terminal Area Chart near Death Valley?

texts:
Due west of KLAS and Death Valley are a large number of MOAs and Restricted areas. On the sectional and terminal area charts, there are thin magenta lines snaking over some of the mountain tops.

What do those lines represent? They don't seem to be a mode C veil of any sort, and the legend doesn't otherwise mention a thin magenta line without spikes.


texts: How does an accessory drive hydraulic system power a crop duster pump?

texts: Aerial agricultural spraying uses pumps, which are usually powered electrically from the starter/generator. Now I have read, that these pumps can also be powered by an accessory drive hydraulic system. How does that work?


texts:
I'm trying to find out which plane a Sundstrand UFDR came from and have narrowed it down to 5 possible planes.   How can I confirm which of the 5 planes the FDR recorder came from?

I did a lot of research and found out that Boeing had a contract to install Sundstrand UFDRs into their 767 and 757 planes.

The Sundstrand UFDR in question has one of the tags stating "BOEING PART NUMBER" instead of "CUSTOMER PART NUMBER" and a date code of 8822, made the 22nd week of 1988.  It also has two SAS identification tags on it, from SAS airline.

From SAS annual reports archived on their website, they stated they had ordered five 767s, and indeed five 767-383ERs were delivered to SAS from Boeing in 1989.

SAS no longer owns any of these 767s, 2 are listed as still active, one as stored and 2 are listed as having been scrapped, one scrapped in 2010, and the other in 2017.

My research also shows that this particular model UFDR, would have had to be removed from all planes it was in, by Jan 1st, 2016, as all such magnetic tape FDRs had to be replaced with digital chip technology.

Now the ONE 767 in this group was scrapped, while a UFDR would have still been allowed.   The other plane was scrapped after it would already have had the newer digital chip storage FDR in it.

What typically happened to these Sundstrand UFDRs in 2016 when they were removed from planes and replaced with the newer ones?

Where and how does one go about finding records on which serial number FDR was on a particular serial number Boeing plane?

Being I have narrowed it down to 5 planes, how do I now confirm which of the 5 planes it came from?


texts: What are the (new?) FAR Part 141 rules for simulator hours for private pilots?

texts:
My son has started on his own at a Part 141 school in Vacaville CA that claims that mix of 18.9 hours flight and 36.3 simulator hours both with instructor will allow him to check-ride.  (Note that 18.9 allows only for 5 hr solo, 3 hr cross-country, 3 hr night, 3 hr instrument, and 3 hr prep check ride.

Are they blowing smoking knowing that he will need at least 16.1 hr more flight time to meet minimum FAR requirements? And knowing the national average is 60 hrs flight time. Isn't this just a marketing job to lower the total package price ($7,611) with more simulator time?


texts: Why are the Constellation's nosewheels canted inwards?

texts:
Why are the nosewheels on the Constellation canted in a few degrees? Is it to ensure both tyres have ground contact during tight ground turns?
I've observed that on the A320 during tight turns that one wheel comes completely off the ground. The A320 nose leg also sits at an angle; would it benefit (if needed) from angled nosewheels?

http://www.ipmseaglesquadron.org/ES-Forums/index.php/topic,1639.0.html


texts: How does the U.S. Overflight Fee system work?

texts:
After going through the Overflight Fees on FAA.GOV, the following is clear and self-explanatory:

Exact fees
Method of Payment (online, via Pay.gov as mentioned on the page).

What's not clear to me is the following:

  The FAA charges overflight fees to operators of aircraft that fly in
  U.S.-controlled airspace, but neither take off nor land in the United
  States.

Does this mean that international flights that land at any airport within the U.S. are not liable for overflight fees, and that they're only liable to pay the other fees such as airport charges etc.?
How is the invoice/bill delivered to the responsible party? I
believe airlines/commuters have accounts that get billed, but what
about private jet owners?
What would be the circumstances if, say a private jet owner/operator
departs from Canada, lands in Mexico and doesn't pay the invoice?
What if such a trip is made once a month for a long period of time
without paying the due fees. Does that jet "not get permission" to
enter U.S. Controlled Airspace?


texts: What is an optimum engine-out bank angle?

texts:
I've heard three methods you should use in a multi-engine aircraft when engine-out, each recommending a different amount of bank:

Wings level, hold aileron to maintain roll and correct using rudder.
Ball centred, ailerons flush and correct using rudder.
5 degrees bank angle, hold aileron to maintain roll and correct using rudder.

Which one of these will result in the highest climb rate, and are there any advantages to other methods which don't give the best climb rate?


texts: How do you find the difference in degrees between two headings?

texts:
This may be more of a math question, but it is specific to aviation so here goes:

Given an origin heading and a destination heading (origin heading is the heading you're already flying at and destination heading is the heading that you want to turn to), what are the formulas for degrees of separation between those two headings for a left or a right turn?

So if you are heading 190 and you want to go to 020:

The left turn formula should output 170 degrees.

The right turn formula should output 190 degrees.


texts: Can ICAO airline designators be reassigned to a new airline?

texts:
Is it possible for three-letter ICAO airline designators to get reassigned?

In particular, I'm trying to find out if BKL was previously used for Baikal Airlines (ceased to exist in 2001) and reassigned to Barkol Airlines (founded 1996, although it's unclear when they received their ICAO code).


texts: How are brakes cooled on heavy aircraft?

texts:
As kinetic energy is not stored or recycled, large quantities of heat have to be evacuated in a short period of time when aircraft abort their takeoff or land:

B777 brake test, Youtube

Which approximate quantity of energy is transferred to the brakes in a rejected takeoff for heavy aircraft, e.g. Boeing 777 or Airbus A380? What are the typical systems used to cool brakes on these heavy aircraft? Is cooled air or liquid used, or just ram air?


texts: What is this airplane I saw with propellers behind the engine and canards on the top of the plane?

texts:
While playing Pokémon GO, I saw a plane with:

Propellers behind the engine.
Canards at the tip of the plane.
Normal-looking tail with a flat wing at the end of the upright bit.

I know these are probably not the correct terms, but I'm not sure what else to call those components.


texts: How does turning a small plane by opening the doors work?

texts:
I've just watched a video of a small Cessna turning not with ailerons or rudder but by opening its doors. They said that the door acts like a rudder, but in the video one of the guys opens the left door and the airplane rolls right. That doesn't  make too much sense to me...

I've been searching on the internet and I found a different explanation which  stated that the airflow stacks up below the wing because of the door and then an over-pressure is exerted making the airplane roll into the opposite direction, in this case to the right (which is what can be seen on the video). Can anyone confirm this second explanation?

And if I wanted to roll a Piper or any other low-wing aircraft by using the doors, what would the airflow's behaviour be?


texts: How is auto-rotation different in coaxial rotor helicopters?

texts:
Coaxial Helicopters have two main rotor sets, one on top of the other, spinning in different directions to eliminate the need for a tail rotor. I've heard it said they're also more maneuverable, all else being equal.

So how is auto-rotation different (if anything) for these kinds of helicopters? Is it any easier? Do you get longer range and/or slower (safer) descent speed?


texts: Why do you need to provide your arrival airport when you close a VFR flight plan?

texts:
I file VFR flight plans all the time, now that 1800wxbrief.com makes it so easy to open and close them.

Opening is easy, just click the activate button, but when it's time to close the flight plan, you have to type in your arrival airport.  Of what value is that particular piece of information to FSS?  Is there a historical reason why they request it?


texts: What are some of the fastest UAVs? How do the pilots ensure that their controls are being transmitted to actions?

texts: I would clarify that the drones I refer to are UAVs that were piloted using a control station. I know many military projects include such capabilities but I want to know how pilots work on such supersonic UAVs and fly at such high speeds. I read that it was an alternative to the high risks of piloting and training a supersonic aircraft pilot, but I'm curious about such projects and how they fly at such high speeds and how they know when they're in control and when do they know that these crafts are out of control.


texts: Do pilots have separate volume knobs on the radio panel?

texts: I have about two hours in a Cessna 172 so my instructor always managed the radio for me. I found it too loud at some times and too quiet at others. Can I tweak mine without bothering him? I forgot to ask last time. Is this the same for most / all planes or does it vary a lot?


texts: On large aircraft, why do flaperons not run the full length?

texts:
This is a 777 flaperon. It looks rather tiny, compared to the flap.
There have been air disasters where the airplane rolled uncontrollably for one reason or the other. It seems to me that a larger roll control authority could have helped.
Admittedly, flaps are slow, and speed-limited, so less suitable as control surfaces. But at least, could they not be used for trim?


texts: Do ducted fans have a future in forward flight aircraft? Can they be made more efficient than open rotors?

texts:
I'm fascinated by how ducted fans have the ability to be more efficient than open propellers of equal diameter in vertical flight through the use of tight tolerances, lightweight duct material, proper duct lip shape, and other factors. However, when learning that these benefits don't translate over into horizontal flight due to the duct's induced drag and pitching moment, I'm wondering if we'll ever see ducted fans in future aircraft.

I'm aware of the NASA ducted fan manned-aircraft project that failed in the 60's, but today I found out about AgustaWestland's Project Zero and noticed that they tilt the ducts and include fixed wings to provide sufficient lift. How would an aircraft like this compare efficiency-wise to something like a similarly sized  two rotor helicopter?

AgustaWestland Project Zero


texts: What gas turbines have the following configuration?

texts: Is there any jet engines--with published data on the dimension of the turbines and compressors--that are of the configuration of 2 Low Pressure compressor, 8 High Pressure compressor, 2 High Pressure turbine, 5 Low Pressure Turbine? Thank you very much!


texts: Why does the C-2 left inboard stab not have a rudder?

texts:
As visible in the following picture

(wikimedia.org)

the left inboard stabilizer doesn't have a rudder but the right one does.

Wikipedia on the C-2 describes it as:

  The C-2 has four vertical stabilizers, of which three are fitted with
  rudders. A single vertical stabilizer large enough for adequate
  directional control would have made the aircraft too tall to fit on an
  aircraft carrier hangar deck. The four-stabilizer configuration has
  the advantage of placing the outboard rudder surfaces directly in line
  with the propeller wash, providing effective yaw control down to low
  airspeeds, such as during takeoff and landing. The inner-left
  stabilizer lacks a rudder, and has been called the "executive tail",
  as it has nothing to do compared to the other three.

The rationale explains the primary design, but no explanation for the "executive" tail. Can anyone explain why the C-2 is designed this way?


texts: What role, if any, does visual aesthetics play in the design of modern airliners?

texts:
Another way of asking the question:

  Are there any distinctly identifiable features of particular modern airliners that are there for design reasons that have less to do with engineering than with appearance?

or:

  Could one look at at a modern airliner, and point out something in its design, however small or large, that is there because "it looked good"?

To be clear about a few points:

By modern I mean since the 707.
In visual aesthetics I only want to include physical form - contours, placement of parts, proportions etc - and specifically want to exclude livery, colour, and so on.
I'm not interested in inessential matters like the design of the interior, but in the airframe, engines and so on.

I'd be pretty surprised to discover that any aspects of design allowed aesthetics to trump engineering consideration, but perhaps there are examples where aesthetics played a part because the choices, from an engineering point of view, were equally viable.


texts: How is flyblackbird.com operating under Part 91K?

texts: The website states they're not a Part 380. Love their service -- how will they avoid the same fate as Flytenow?


texts: Which Airline don't use the Flight Number 191 anymore because of bad luck?

texts:
This question came up while reading an article about mysterious plane incidents. It told that some airlines do not use the flight number 191 because of bad luck.

  In fact, there have been so many catastrophes that, much like hotel
  owners who refuse to have a 13th floor, some superstitious airlines
  have completely done away with the number “191.”

Does somebody know some Airlines who are not using this flight number
for that reason?


texts: Can lift be equated to how much air is moved?

texts:
The explanation for lift that I find easiest to visualize is that air is deflected downward by the wing. This downward action causes an equal and opposite reaction of an upward force against the plane, as in accordance with Newton's third law.

As you can see from the image below the red lines both end lower than they started.

Air at sea level weighs 1.293 kg per cubic meter. The acceleration due to gravity is 9.8m/s².

That comes up to 9.8N of force being needed to keep a 1kg aircraft in the sky. With perfect efficiency this equals 9.8 watts.

If trying to hover VTOL aircraft, can you multiply how much air a propeller can move, by how fast it moves it to predict lift force? Since force is mass x acceleration?

Or do fluid dynamics work differently as the air exiting the propeller will spread out instead of all going straight down? If that is the case can using a duct with a properly fitted bell nozzle solve this problem? Or am I thinking into realms that I shouldn't be?


texts: What is the history of the name of airway?

texts:
I am studying about airway. And I want to know about the history of designation of name of airway.
I have known that the first name of airway is colored airway(L/M frequency airway) like A586 or G13.
But why we call them colors? I don't know the association of colors and airways. And how was the name of airway changed later?(like victor airway)
Please let me know in detail.


texts: Does MMO (limiting Mach number) assume any maneuvering limits?

texts:
This answer to a question about emergency descents notes:

  [Y]ou can accelerate descents by banking the aircraft
  into a turn. This allows you to increase angle of attack, thus
  increasing drag to keep speeds down, while rotating the lift vector
  away from the vertical so it's not working against you. The
  combination allows for higher descent rates with the same MMO/VMO
  limits.  Some operators train for this, but my impression is not many....

Banking seems like an obvious way to increase drag and accelerate descent when the only objective is to get to a lower altitude (e.g., due to rapid decompression).  So does forward slipping.  Is either ever indicated in manuals or emergency checklists?

I was wondering if such maneuvers might actually be contraindicated: Isn't MMO determined by the stress limits of the airframe?  If so, does MMO (in theory, if not in practice) assume some limit on angle of attack, and would MMO decrease at high angles of attack or slip?


texts: What would be the potential thrust of an "electric jet" like Lilium's?

texts:
Lilium claims to fly with "electric jets". Throwing out the debate over whether a non-combustion compression of a stream of air is a jet or only a ducted fan, what is the potential thrust each of these could be getting?

Edit: since it's not compressing, what potential lift could the Lilium prototype engines provide, and are there examples of electric engines today that provide compression in a significant way?

Ignoring the stability issue of Lilium as well. Just curious about the ducted fan design they have. Also ignore the problems with it being electric and battery powered please :)


texts: What is the official term for a gas / petrol station for planes?

texts:
I'm talking specifically about small airports where they don't have the fancy equipment and they actually have to go to a specific place to refuel for example cars go to gas station / petrol station so:

Is there an official term for a fuel station specific to planes?


texts: How does a turbofan with afterburner continue to function in extreme humidity and rain?

texts:
From what I understand, the fan(s) collect(s) and compress(es) air into the compression chambers, where fuel is added to the air & combusted to create an even bigger pressure/thrust, right before the fuel-air mix hits the final chamber where even more fuel can be added & combusted (if you go +afterburner).

My question is this: If it's very wet out, and the engine is sucking up multiple gallons of water per second, then exactly how is combustion achieved with all that water contaminating the air?


texts: Can a large passenger aircraft recover from a stall?

texts: In fighter aircraft, we know that they have good enough of maneuverability. But in case of a passenger airplane, if a stall happens is the aircraft maneuverable enough to recover from it?


texts: Reason why heavy aircraft are allowed to land but not to start

texts:
I stumbled upon this article (German)
It says that a few of Lufthansas 747 are grounded at Twente airport. They were parked there because of COVID-19 at an aircraft recycling company.
Now the airport does have the license for such heavy aircraft to land, but not to start, which normally isn't a problem as they land there to be recycled.
Unfortunately the article doesn't state the exact requirements the airport doesn't fulfill. It just says something about safety issues. What could it be that allows the aircraft to land safely but not to start?


texts: Does a line up and wait instruction clear me to backtrack the runway?

texts:
I had an interesting occurrence at the start of a recent flying lesson, at an aerodrome with ATC service. We were holding at A and completed our power checks. We hadn't requested nor been offered an intersection departure, and that is not a usual procedure at this aerodrome.

"G-AB ready for departure"
"G-AB via A line up and wait runway 23"
"Via A, line up and wait, runway 23, G-AB"

Following this, I entered the runway and turned to backtrack to the threshold. At this point my instructor said I should have turned the other way to line up at the intersection, because they didn't clear us to backtrack. Was he right to complain, or was I correct to use the full runway length?

Notes

A is only about 20 m from the runway threshold, and this runway is huge, so it makes little practical difference in this case.

At this aerodrome, they usually give LUAW instructions as "via [point], enter, backtrack, line up and wait runway 23". I checked CAP 413, and it doesn't mention "enter, backtrack, line up and wait" as phraseology, so I'd expect a clearance to LUAW entitles you to the whole runway unless you've already agreed an intersection departure. However, it's CAP 413 section 4.24 that introduces the "via A" phrase, and it has this to say:

  When line-up will take place at a position other than for a full-length runway departure the intermediate 'Holding Point' designator shall be included in the line-up instruction. Controllers may include the runway 'Holding Point' designator in any other line-up instruction when considered necessary.

It gives an example, and the only other example with "via" is in the context of an intersection departure. As I said, at this aerodrome they usually include the "via"; maybe they just always consider it necessary. Is not saying "backtrack" here significant, even though it's not a standard part of a LUAW instruction?


texts: Why would one cylinder on a Continental O-200 run cold at idle?

texts:
I have a Luscombe with a Continental O-200 engine. The #4 cylinder is running cold at idle, does anyone have an idea why? The other three cylinders are running fine.

Some extra information:

The engine has only 300hrs SMOH but it hasn't run for two years and it's just had some maintenance work done (carb, filters, plugs)
Cylinder #4 is cool to the touch, the others are too hot to touch
A mag check seems normal (expected RPM drop on both mags)
A compression check seems normal (76/80 on #4 cylinder)


texts: What does the pressure distribution over a glider's wing look like?

texts:
Can someone explain the design of glider wing airfoils and the subsequent pressure distribution over them?

I hypothesize that:

The pressure distribution should form a resultant force in the forward, upward direction, since two components of force are required to maintain equilibrium in the flight of a glider: a) lift - in equal opposition to weight, and b) a forward component of the total reaction generated by the airfoil - in opposition to drag.
Thus I conclude that the angle of attack of a glider airfoil relative to flight direction would be negative, in order to achieve a forward component opposing drag; although it would be positive relative to airflow, such as to generate low pressure over the wings. Either that or the camber is designed such that the two mentioned criterias here, (a) and (b), are upheld.

Should there not be any opposition to drag, I would expect to see the glider decelerate in the forward direction, until the airflow stalls over the wings, and the glider loses lift and falls.

I am also curious to know about the various designs of glider airfoils: a) what are the criterias defining them, and b) how do they differ from those of powered aircraft, if there are any differences at all?


texts: Why is the VFR traffic pattern area at some airports different from its IFR circling approach area?

texts:
Take Half Moon Bay Airport (KHAF) as an example.

Under VFR, the traffic pattern is right pattern for RWY 30 and left pattern for RWY 12. This implies the downwind leg is to the EAST of the RWY 12-30, and therefore we should fly over the land at TPA 999'.
However, looking at the IFR plates, both RNAV (GPS) Y Runway 30 and RNAV (GPS) Y Runway 12 indicate we are required to circle WEST over the water at 800', since that "Circling NA east of Rwy 12/30".

I understand it is likely that we have more vertical room over the water since there are no obstacles there. However, I don't get the reason to require VFR traffic over the land. Is it for VFR/IFR traffic separation?

Some reasons that I came up with

Favors the water, against the land: Terrain/Obstacles, Noise Abatement.
Favors the land, against the water: Marine Sanctuary Protection.


texts: Why do the engineers need to be on board during testing?

texts:
I just finished watching National Geographic's Megafactories: Boeing 747-8.

During the test flights, a bunch of engineers are on board the plane, presumably controlling the water tanks that distribute weight, and collecting the data.

Another time I'd seen it was when they were testing detection systems for microbursts. There were about a dozen engineers sitting on the plane, watching monitors while the crew deliberately flew into hazardous conditions.

Why do they risk the safety of these engineers, when presumably the work they're doing could be automated or controlled remotely? For data to be observed, couldn't they do that from the ground?

Is this a case of "we've always done it this way?" Even now that we probably have the technology that would allow the engineers to avoid having to go on test flights, I'm guessing that changing this procedure would be a lengthy and difficult process.

Besides the pilots, why does anyone else need to be on board?


texts: Why overhead bin was put on top of passengers head?

texts: Hello I'm just curious about the reason to why the overhead bin was most commonly being put on top of our seat and head.


texts: What is the typcial descent rate of a helicopter?

texts: I'm not a pilot, just asking out of curiosity. What is the typical descent rate for a helicopter when landing? I found the answer of 300 feet per minute on the web, but I want to confirm this. If this is true, than a helicopter descending from 2400' to land would take 8 minutes. Is this correct?


texts: When is a runway considered to be wet or slippery for 135 or 121 landing performance considerations?

texts:
For the purposes of following FAA regulations, when is a runway considered to be wet or slippery in the context of landing performance calculations? Specifically, what definitions or guidance on meaning for the terms "wet" or "slippery" should a pilot or dispatcher use in making the determination required by §135.385 or §121.195 as to the runway condition?

14 CFR 135.385 gives the following regulation pertaining to §135 operations of Turbine powered Large Transport Category airplanes:

  Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports.

  (d) Unless, based on a showing of actual operating landing techniques on wet runways, a shorter landing distance (but never less than that required by paragraph (b) of this section) has been approved for a specific type and model airplane and included in the Airplane Flight Manual, no person may take off a turbojet airplane when the appropriate weather reports or forecasts, or any combination of them, indicate that the runways at the destination airport may be wet or slippery at the estimated time of arrival unless the effective runway length at the destination airport is at least 115 percent of the runway length required under paragraph (b) of this section.

Likewise, 14 CFR 121.195 gives the following regulation pertaining to §135 operations of Turbine powered Large Transport Category airplanes

  Airplanes: Turbine engine powered: Landing limitations: Destination airports.

  (d) Unless, based on a showing of actual operating landing techniques on wet runways, a shorter landing distance (but never less than that required by paragraph (b) of this section) has been approved for a specific type and model airplane and included in the Airplane Flight Manual, no person may takeoff a turbojet powered airplane when the appropriate weather reports and forecasts, or a combination thereof, indicate that the runways at the destination airport may be wet or slippery at the estimated time of arrival unless the effective runway length at the destination airport is at least 115 percent of the runway length required under paragraph (b) of this section.

These regulations are effectively identical.

How is this determined? Does the FAA offer a definition (I have not found any such definitions in 14 CFR)? Does an AC give the appropriate definitions? Is the Operator expected to make this determination or to include a definition in the accepted or approved GOM? Should pertinent aircraft manufacturer's data be considered, for example if the AFM includes a definition of "wet runway"?

I am especially asking for any cases where the AFM does not give approved wet or contaminated landing data. Note the difference between approved and advisory AFM data. However, I am interested in knowing any and all ways in which the determination required by these regulations is complied with.


texts: After a crash, for how long is the airport closed?

texts:
International airports are busy places. For example, London Heathrow saw an average of 1,290 "air transport movements" per day in 2014. It seems that a crash at the airport, such as BA Flight 38, would cause major disruption.

Yet, according to that same wikipedia page, flight operations were resumed within hours and basically back to normal within a couple of days.

Another more recent example is Turkish Airlines Flight 1878 crashing on landing at Istanbul. Again, the airport "was temporarily closed".

How are airports able to keep disruption to a minimum after (what seems to me to be) a fairly major incident, potentially involving a wrecked plane sitting on the runway? How do they move the wreckage and re-open the airport so quickly?


texts: What is a 'Wing Loop Fault' on an A320 series Aircraft?

texts:
I was recently involved in a flight that had issues before take off. The plane was an Airbus 321.

It was explained to me as being a "wing loop fault". The problem was that the ECAM messages were displayed differently each time and were inconsistent. The flight was aborted just before take off (for safety reasons) but the problem was fixed soon after by replacing a part.

Can anyone explain this problem with the wing loop to me in more detail. What could have gone wrong and what was the likely fix.

Also, what maintenance and pre-flight checks should occur on the "wing loop"?

Sorry for any vagueness in my question, I didn't receive much information.

Edits

This was on aircraft G-OMYJ around the 24th August 2013
My route was (EMA) --> (DLM), flight TCX5894. But the fault may have occurred on the previous flight. The details are unfortunately hazy. Is there anyway of me finding the whereabouts of the plane in the days leading up to this incident?


texts: What is needed to remove my CPL restriction after becoming a US citizen?

texts:
I hold a US commercial pilot certificate based on my foreign commercial pilot certificate. This was allowed prior to the ruling that foreign pilots would only be issued a private certificate. On the back of my certificate there is a statement, "Not valid for the carriage of persons or property for compensation or hire or for agricultural aircraft operations".

I am now a US Citizen and I am wondering what I need to do to have this restriction removed.


texts: Are plane's black boxes essentially useless tool in the modern age and how to improve upon it?

texts:
I am just reading the latest news on the air plane crash that happened couple days ago and it dawned on me that one too many times have I read a story on the NY Times where after black box is obtained, it provided no additional information and almost always resulted in mystery.

MH370 of course demonstrated the failure of a tool such as the black box which has limited battery and no accessibility. Many commented at that time even my own phone can be quickly located once lost, how do they lose a component in a couple million dollar passenger plane?

Air Indonesia crash further demonstrated how due to noise, the recorded data cannot be made out exactly what happened. Yes, that is precisely the problem with a voice recorder - noise is captured as well as speech and if SNR is high enough, you don't hear the speech. You would have thought engineers in this century knew better.

Many have advocated a live video streaming device such as those for CCTV. Other have suggested float on water or a better accessed versions of modern black boxes. What is the technological infeasibility here that is preventing electrical engineers from taking a more active stance towards creating a better black box? What are some of the ways that a better black box can be made?


texts: How is paint embrittlement countered in high altitude aircraft?

texts:
There are cases of aircraft that are not designed for high altitudes that can still fly there and as a result the paint on these aircraft "falls off".
Although most aircraft have paint that is chosen to work up to their maximum flight altitude (that is mainly limited by the engine and by aerodynamics), sailplanes are an example of aircraft that do not have a fixed maximum flight altitude. As long as thermals push these aircraft higher, there are few limiting factors for their maximum altitude, as the necessary lift and thus velocity at high altitudes is not as significant as other aircraft since they have a large wing area and low wing loading.

My question thus is not centered around the aerodynamic limits and answers such as "it is selected to work up to its maximum flight altitude" but rather around the process of the selection of compatible paints. It may include design and selection considerations for civil aircraft at 10.000m AGL and for high altitude military fighters. Does the paint over the aircraft surface change due to additional influences e.g. front edge heating?

If necessary, an overview of the different paint types used (at certain altidudes) would be appreciated.


texts: Is there an FAA ruling about the airworthiness of piston engines with less than 60 on the compression test?

texts:
We've been having some discussions around if there was a specific ruling from the FAA that explicitly said that if a cylinder was showing less than 60 on the compression test, the FAA deemed it unairworthy.  I've heard that, it's a rule-of-thumb and not a ruling, but I don't know for sure.

Has this been conclusively made into a ruling from the FAA, or does it exist as a rule-of-thumb and there are other factors to consider?

This would be specific to United States/FAA and 4-6 cylinder Lycoming or Continental piston engines.


texts: What are those hatches on the engines of a B-2 that are open during takeoff?

texts:
I just watched this drool-inducing video of Northrop Grumman B-2 Spirit, And noticed that there are a couple of hatches near each engine, which were open:

I initially thought they were open for some sort of maintenance. But the video features a takeoff roll of the bomber (around 5:00 minute mark), and I again noticed that the hatches were open during the roll. However, they were retracted immediately after the aircraft left the ground (around 5:25 mark):

This makes me wonder if these hatches serve some special purpose. What are they, and why are they open during the takeoff roll?

Edit: Please don't say you don't see an aircraft, because the landing gear doors are down and radar signature is immense due to that. :)


texts: Do the engines still spool up when reverse thrust is selected, but the reversers are not deployed?

texts:
The recent question When a large commercial jet touches down, is it committed to stopping? referenced the crash of Red Wings Airlines Flight 9268, which overran the end of the runway at nearly full touchdown speed due to failure of the reversers to deploy. According to the Wiki article, due to a crosswind, the aircraft touched down on only one of its main gear. Even once the nose gear was on the ground, the right main gear strut had still not compressed. The pilots selected full reverse thrust when the nose gear touched down. Since the right gear strut had not been compressed, the reversers were not deployed, however, the engines still spooled up, resulting in forward thrust.

I understand the reasoning behind not deploying the reversers when one or both of the main gear struts isn't compressed. However, it seems to me that preventing deployment of the thrust reversers should also prevent spooling up the engines for exactly the reasons that the Red Wings flight crashed. Applying full forward thrust when the pilots have selected full reverse thrust seems like a very bad idea to me.

I'm wondering whether this behavior is typical of modern transport-category jets. That is, would, for example, a Boeing or Airbus aircraft prevent the reversers from deploying, but still spool up the engines (as the Tu-204 did in this accident) or would they also prevent engine spool up when reverse thrust is selected while thrust reverser deployment is locked out?

Am I missing a reason why still spooling up the engines would be desired when reverser deployment is locked out?


texts: Why do we use dimensionless expressions in flight mechanics and aerodynamics?

texts: Why do we use non-dimensional expressions in flight mechanics and aerodynamics? We could as well directly calculate forces and moments; would that not be more relevant to the specific problem?


texts: Are turbine and compressor blades and vanes cast or forged?

texts:
I was wondering how blades and vanes are typically made in commercial jet engines. Would you typically use investment casting to make compressor blades or just in the turbine section to accommodate the cooling channels?

Also, how much does a first stage high pressure turbine blade cost? Are they more expensive on the newer engines, for example, the LEAP vs. CFM56?


texts: What sort of debris has been found in 737 Max fuel tanks?

texts:
There have been numerous reports of Boeing finding "foreign object debris" in the fuel tanks of its 737 Max airliners.

It's not clear what this debris is. It could range from a couple of missing screwdrivers and a blowtorch, to perhaps microscopic particles that might contaminate the fuel.

Has Boeing released any details of what these objects are? And, more generally, how unusual is such contamination?


texts: Are there any preventive measures against bird strikes while in flight?

texts: Most of the preventive measures for bird strikes are at/around the airport but what are some of the ways that can be used to prevent bird strikes on the plane as it is climbing or in flight?


texts: What orders of Ram Rise Coefficient (Recovery Factor) are commonly encountered?

texts:
The answer to the question about OAT, RAT, TAT, and SAT has the following:

  Problem is, not all instruments will compress that air in the same way, and not all of them will pick up this Ram Rise entirely. So they will publish a K, a ram-rise-coefficient (also called recovery factor) meaning how much of from the theoretical Ram Rise they actually pick up.

It appears for speeds exceeding 1.5 Mach, Ram Rise starts achieving oppressive values. At 1.6 Mach, and -25C SAT we're already dealing with temperature rise to above 100C. The only "redeeming factor" is K, which may prevent such rapid and drastic rise for a short while.

What orders of magnitude does K appear in, in typical scenarios where ram rise starts playing a role - a supersonic fighter, a missile, a rocket?


texts: What does AOE on the sectional chart mean?

texts: What does the AOE notation on the sectional stand for? This appears at the bottom of the information for an airport as the final line.


texts: Can a tiltrotor fly safely with one engine?

texts:
I am curious about tilt-rotor feasibility (such as AW609) against fixed-wing and rotor-blade aircraft (conventional helicopters).

One important issue that immediately arises in my mind is that both propellers must be highly robust against failures. This is translated in a significant disadvantage against traditional aircraft designs since:

Fixed-wing which are equipped with more than one engine have redundancy, or at least they can glide long enoughg if only equipped with one engine
Rotor-blade can still perform an emergency landing in the event of a main engine or tail-rotor failure, as this question points.

So the big question is: Can a tilt-rotor fly safely (or at least perform an emergency landing) with a faulty engine?

P.D.: For the sake of the question let's presume that the engine has not blown up or has suffered from structural integrity failure (e.g. one blade is missing).


texts: What is this orange container labeled "Flight kit wheel"?

texts:
What is this orange container for?
It reads

  Flight kit wheel. Do not remove.

What's a "flight kit wheel"?


texts: How to log pattern work time during X-country?

texts:
I am working on my IFR part 61 and must have 50 hours of X-country as PIC.

Lets say my instructor and I fly to an airport that is 55 miles from my take off airport - it takes us 0.8 hours from take off to land.
Then, on our way back, we do pattern work at another airport - 0.4 hours to fly and 0.7 hours for pattern work.
Then, final leg of flying - 0.3 hours.

Total flight time - 0.8 + 0.4 + 0.7 + 0.3 = 2.2 hours

What is the best and legal way to log this 1.5 hours of X-country, in my log book? If I could, I would like to take advantage of the 0.3 + 0.4 hours during my return flight as X-country time.


texts: Atlas was the guy in Greek mythology that was literally carrying the world/planet in his shoulders. But was does "M" mean? Military? That's a guess, though...


texts:
I was up this past weekend on my first solo cross country and decided to request VFR flight following and was a bit confused at what happened. For this question I will set up the actual situation as an example.

I was over the Pottstown VOR (PTW) heading to Lancaster (KLNS) on the 269 radial. I decided to call Reading (KRDG) approach for flight following as they were the closest approach or so I thought. They informed me that I was still in the Philadelphia airspace and advised to contact them. Now in the past (with my instructor) on the same flight in just about the same location we had taken flight following from Reading approach.

So,

How do you know who to hail for flight following?

I was in the Philadelphia Mode C veil, is that why they sent me to Philly Approach?


texts: What are the pros and cons of PPL training at class C airport?

texts:
I'm looking to start PPL training soon, and the closest airfield is Austin-Bergstrom International, which is a class C. The only downside I see to doing training at KAUS is that the few PPL programs there has planes no smaller than 172's, which is 15% more costly than the alternative PA-38 at an airfield 30 miles north, or marginally cheaper 172's 30 miles south in San Marcos. Instructor rates are roughly equal. 150/2's don't seem to exist around here.
So the question is, are there advantages to training in a class C that make up for the cost difference? What disadvantages do you foresee?
Thanks.


texts: Are there any airports that require arriving/departing flights to fly under an obstruction?

texts:
Are there any airports with approaches and/or departures that require pilots to fly under an obstruction at some point (thus meaning that, for at least a short segment of the approach or departure, there is not only a minimum safe altitude, but also a maximum safe altitude)?

I can imagine a few situations where this might occur, such as for an airport at the bottom of a deep, steep-sided valley with powerlines or a bridge across the top of the valley, but I don't know if any airports like this actually exist.


texts: How can a stowaway hide in the undercarriage?

texts:
I'm curious about how and where a stowaway could hide in the undercarriage of a plane.

According to this news report:

  The man, believed aged 24, was found in the undercarriage of the
  plane and was taken to hospital.


texts: Is flight data recorder erased after every flight?

texts:
Flight data recorders store massive amounts of data per flight and despite improvements year on year with data storage as with Moore's law, carrying larger and larger amounts of data can become expensive, through larger hard drives and the extra weight.

So, is a flight data recorder erased after every flight? If so, after how long and by whom, is it automatic on landing, engine shutdown or it's one of the pilots procedures on landing?


texts: Does the Piper Aztec have flaps and slats and if so what kind?

texts: I was just wondering if any one knows if the piper Aztec has flaps and what kind. Also if the piper Aztec has any other high lift devices.


texts: Why aren't airliner windows aligned with their seats?

texts:
On a recent airline flight, I noticed that the spacing of the plane's windows was different from that of the passenger seats: some of the rows had a window directly in line with them but for others, the windows were partially obscured by the seatbacks in front or behind.

Is there a reason that the windows aren't manufactured with a regular spacing to align with the seat rows? Does it have to do with the fact that different airlines may be using different seating configurations for the same model of aircraft?


texts: In general, what are the RPM ranges/differences between the various compression stages on a 2 or 3 spool (LP,IP,HP) turbojet/fan engine?

texts:
I have a general interest in jet engines and am pretty new to the topic so I wanted to toss this question into the wind as I don't have any previous experience or knowledge to pull from and haven't really found a similarly posted question anywhere else.
In the small amount of reading that I've done when looking at the RPM ranges for the various compressors (LP,IP,HP) generally the LPC spins the slowest and the HPC usually spins the quickest and, if the engine has one, the IPC has an RPM range that falls between the two.
So my question is what sort of speeds or fluctuation in speeds for each shaft could we expect during takeoff/flight/landing? For example does the LPC fluctuate more or less than the HPC/IPC or do they remain fairly constant while in flight?


texts: Make a 3 engine turboprop electric or steam hybrid aircraft?

texts:
Was thinking about this, have a 2 engine regular turboprop with a third electric engine for extra performance (imagine a DC3 like the Conroy Tri-Turbo-Three). The 3rd electric engine would be run from the turboprops' alternator/generator and solar, with minimal batteries for emergency use.
An alternate version has the 3rd engine run by steam, the turbine engines produce the exhaust heat to power it, and cold upper air temps will cool the steam quickly.
In either case the 3rd engine does not have to be as powerful, it's just there for performance/emergency.  Does either sound feasible?


texts: What was the earliest plane in push-pull configuration that flew or at least took off?

texts:
I am looking for the earliest plane in push-pull configuration that flew or at least took off.

I have found such planes ("Short Triple Twin" and "Short Tandem Twin") flown in 1911. So, I would be especially interested in push-pull flying machines that took off before 1911.


texts: Could modern unmodified Airbus aircraft be used for zero-G flight?

texts: ESA operates a mostly-stock A310 for their zero-G science flights, which doesn't have the flight envelope protection of more modern planes. Even then, a third pilot is required to monitor warnings to sort out the ones normally encountered in the parabolic maneuvers from unusual ones. If this aircraft were replaced with a modern Airbus (newer than A300/A310), would it be possible to fly these parabolic maneuvers without going into alternate law or doing other modifications to the control system?


texts: When may commercial pilots release their shoulder harness?

texts:
In one answer to a similar question I found a hint to 14 CFR 91.105:

  (b) Each required flight crewmember of a U.S.-registered civil
  aircraft shall, during takeoff and landing, keep his or her shoulder
  harness fastened while at his or her assigned duty station.

Now, I assume this also applies to Part 121 operations?

What exactly does that mean with regards to when are the shoulder harnesses released in practice? Is there an altitude (i.e. 10000ft) at which pilots usually release the shoulder straps - is that maybe company-specific?


texts: How is the jet engine inlet danger area affected when airborne?

texts:
Boeing published engine hazard areas as shown below:

I am curious as to how the danger area is affected when the aircraft is in flight as the jet engine is still vulnerable to foreign object damage.

Assuming idle power conditions at 10000 ft (or just airborne in general), are the danger zones the same as on the ground? If not, would there be a way to calculate this?
Knowing the danger zone for both idle and full power, would it be possible to calculate the danger zone distance for different power settings? E.g. 50% N1.


texts: How can an altimetry system error during cruise (500 ft at 35000 ft high) cause an insufficient fuel situation?

texts:
So my boss gave me a question today as my daily quiz: Let's say an A321 is cruising on a 6-hour flight. It reaches FL350 30 minutes after take-off. After another 8 minutes there's a discrepancy between 2 altimeters. PFD 1 reads 35000 ft while PFD 2 reads 34500 ft. The pilot decides to make an air-turn back due to insufficient fuel, despite having enough fuel filled while on ground.

The question is, did the pilot make the right decision?

I've done some research. The difference between 2 altimeters is not supposed to exceed 245 ft at 35000 ft. But I don't know how that is related to fuel shortage. Worst case scenario the static port is contaminated.


texts: Under what circumstances is an FAA accident report required?  For example, if two planes are pushing back from a terminal and their wings collide is an accident report always required or does it depend upon damage done to the aircraft?


texts: Why are propeller engines uncommon on airliners?

texts:
My experience in aviation is essentially zero, but looking at Wikipedia it seems like the Tu-95 Bear offers high subsonic speed and extreme range.

I assume that turboprop engines are more fuel efficient than jet engines. If all the above are true then why we do not get to see more rotary engine planes in commercial airline flights?

Is it a noise concern? I see that the TU-95 is apparently the "noisiest military aircraft on Earth".


texts:
The Wikipedia entry for the A380 gives the maximum range at design load as 15,700 km. The equivalent entry for a Boeing 747-400 gives around 14,000 km but distances of 18,000 km have been performed in demonstrations. So I infer the ferry range for the A380 would be even higher.

Is it specified anywhere? Has a flight by an A380 in excess of 15,700 km been performed to date? Could it fly between any two suitable airports on Earth, i.e., farther than 20,038 km?


texts: Flight Level Change or Vertical Speed - When to use it?

texts: I've heard that some pilots have this difficulty to determine the correct use of both features. So, which is the difference between using the vertical speed, instead using the flight level change during a descent? When, and how to use it?


texts: Was the unmanned flight and landing of the Buran spacecraft in 1988 exceptional?

texts:
The Buran had a very sad fate. But in 1988 it has undertaken its first and last flight, which was unmanned and landed with a precision of three meters in a crosswind of 60 km per hour. It lost only 8 of its 38 000 thermal tiles.

What was the level of technology of automated flights in that times? Was it usual that airplanes landed automatically or was that flight of the Buran something like exceptional?

Here is an image of the Buran with Energija launch vehicle:

(source of the image)


texts:
I have an EMAX motor that operates at maximum efficiency generating 200g of thurst. This is the only fixed parameter I have.

How do I find the most efficient wing design for this flying wing, considering my motor should push 200g in order to operate on its most efficient range.

I know the bigger the aspect ratio, more efficient the wing will be and more flight time.

I would like to use a KFm airfoil (cause of its simplicity on building it).

How an RC hobbyst (I am a mechanical engineer too), with not much knowledge on drag, lift coefficients... can come up with an optimal design?

EDIT:

Sorry for being too broad. Let's specify better:

1) my electronics weight (motor, esc, battery, servos...) will be at 50g;

2) I want to use a foam board, typical on rc plane community which is thin and lightweight

3) I want to optimize for flight time, not flight distance.

I am really lost at this, even after searching a lot. I know the vector diagram of my plane (weight is down, lift is up perpendicular to the wing, drag parallel to the wing and I know there are many types of drag but I would assume only the most relevant drag which is the one generated by air deflection and thrust is also parallel to the wing pointing forward).

The only vector that I know how to quantify is thrust and weight. The other 2 I am very lost!

EDITED so it can received answers.


texts: For Airbus pilots, what is your TOD calculation methodology?

texts:
During A330 training, various instructors will have many different types of equations and gateways used to confirm the descent profile and whether or not they are above or below glidepath.

The equations that I used now are

$$ \text{Wind} = \pm 1 \, \text{NM per} \; 5 \; \text{knots (head- or tailwind)} $$

$$ \text{Bleed off Speed} = 1 \, \text{NM per} \; 10 \; \text{knots or} \; 1.5 \, \text{NM per} \; 10 \; \text{knots during descent} $$

$$ \text{TOD} = \frac{\text{Altitude}}{1000} \times 4 $$

But I understand you would have to consider the aircraft weight, temperature, flap settings etc. but I'm not sure how to or even know where to start with that.

Would like to know your calculation or methodology! Any references would also be great!


texts: How much power do planes use when taking off at London City?

texts:
I watched a video of an A318 taking off at London City and it took just 20 seconds from setting takeoff thrust to getting airborne.

BA A318 takeoff @ LCY (takeoff thrust @ 1:23, airborne @ 1:43)

and here's A319 takeoff in a regular 3.5km runway, taking ~38 seconds

S7 A319 takeoff @ OVB (takeoff thrust @ ~3:26, airborne @ 4:04)

What I'm asking is a thought experiment, let's say, we fly from one airport to another, and everything is the same except runway length. In one case it's 1500 m, in another it's 3500 m.

How much thrust does an A318 (or any other aircraft certified to fly at LCY) apply at a regular airport vs on a short runway like LCY? How much thrust is used (in kN) and what is the thrust/weight ratio?


texts: What lifting gas was used for barrage balloons during the world wars?

texts:
During the world wars, various barrage balloons were used to protect targets from low-flying aircraft or similar threats (e.g. V-1 flying bombs), in particular by Britain.
What lifting gas was used for such barrage balloons – the highly flammable hydrogen or the rare and expensive helium?


texts: Why are "Follow Me" cars painted yellow and black?

texts: Why are "Follow Me" cars painted black and yellow, and use square shapes in their design?


texts: How much is an airliner's drag coefficient?

texts:
How much is an airliner's Cd, using the frontal area as reference point. I want to compare values with cars and others objects, tear drops, cube etc.
Is Cd measured at zero lift AoA or when the plane is flying in a straight line?


texts: How could a PA-28 be made to fly higher?

texts:
How would I have to modify the Piper PA-28 to fly at 25,000 feet (same as PA-34 and PA-46)? Could it fly higher?

Larger wings, other wingform, bigger motor something else? Do you have to change the whole construction of the plane?


texts: Could passengers realize a possible emergency?

texts:
First, to clarify, I'm not looking for nightmare stories here. I'm not curious about the fears of passengers but rather about what's actually noticeable for them. It's pretty clear that passengers not flying too often tend to be afraid during turbulence. But, I suppose, very few of them ever experienced a stall or similar.

Now, reading about crashes like the one of AF447 where a pilot only very late in the emergency situation re-enters the cockpit, I'm curious about why that is. I've never been on a plane during a stall, let alone an airliner. Don't passengers (and thus a pilot outside the cockpit) experience a stall as something very unusual, dramatic event? As another example, the crash of 4U9525 which was, as I understand it, a very "common descent": could a passenger even notice a difference between the upcoming crash and, say, an emergency landing at a close airport that the pilot just didn't have the time to explain beforehand?

Given "weird feelings" during flights, often related to turbulence which is not at all dangerous -- can a passenger "feel" the difference between those, a controlled flight into terrain, and an imminent crash?

Update

I disagree with closing this questions as a duplicate of What things can a passenger look out for, to indicate an emergency?. I was not looking for how passengers could intercept with flight management. Let's make it more concrete with the AF447 example then:

According to Wikipedia, about half a minute after the problem of wrong speed indication occurred, the aircraft went into stall. Another three minutes later the now returned pilot realized the stall only after he was made aware of the PF pulling up the whole time. Given this example, does a stall with an A330 feel so much "normal" that even a highly experienced pilot couldn't "feel" the missing lift? Will the passengers have thought the flight was still normal at this point?


texts: What are the reasons behind switching FDs off for a VOR approach?

texts: Why do SOPs ask to switch off flight directors and enter Vapp into the FMGC while carrying out a VOR approach on Airbus aircraft? My question pertains to when we disengage the AP. Why do we carry out these actions?


texts: Can a fixed-wing plane jump up by blowing air over its wings?

texts:
NASA's X-57 electric plane has 12 wing-mounted propellors which drive air past the wing.

This video describes how the resulting increased air velocity causes an increase in the amount of lift the wing generates.

Suppose the propellors could generate enough airspeed over the wing to lift the entire plane -- could the plane then jump into the air without needing a runway?

This would require that sufficient lift is generated before the propellor thrust (minus wing drag) exceeds the craft's friction with the ground -- otherwise the propellor thrust would push the craft forward some before a liftoff could occur. And that leads to my secondary question: Is blowing air over a wing a more efficient means of achieving lift than would be directing those propellors downward rather than laterally over the wing?


texts:
When I read about the A-10 I'm met with statements (e.g. Wikipedia) such as:

  The A-10 is exceptionally tough, being able to survive direct hits from armor-piercing and high-explosive projectiles up to 23 mm. It has double-redundant hydraulic flight systems, and a mechanical system as a back up if hydraulics are lost.

What about the F-16 (from A to the latest block 70/72, maybe even F-21 should be included)? Will even small arms fire risk killing the pilot as well as destroying vital systems?

Although it was not designed as a ground attack aircraft, it seems that its role in ground support missions becomes more and more prevalent. The aircraft has also shifted its design goals from being as light and fast as possible to be heavier and feature more complex systems. The F-16's weight seems to only go up with each revision.

If the F-16 is supposed to loiter and provide ground support, it seems that some light (composite? Kevlar?) protection for at least the pilot from small arms fire and slightly heavier weapons would not be a bad idea. Keep in mind that I'm naive about this though, which is why I'm humbly asking.

From what little I know about the F-16, I believe it has quadruple redundant flight computers for its fly-by-wire system, and also has a redundant hydraulics systems (A and B, isolated by a check valve) which both can operate the FLCS (although beyond this, there are differences, A and B are not duplicates), and the EPU.

Design choices like this are obviously there to ensure the F-16 survives when systems fail. However, perhaps they are intended to ensure safe fail-over in terms of non-combat damage and failure.

I also understand that adding armor to a light and agile combat aircraft would be painful, as it adds weight and reduces flight time, makes the airframe thicker with perhaps slightly higher surface area/drag coefficient (?), and probably adds stress to an airframe that is supposed to be able to pull many G's in combat.

I've never heard of any armor whatsoever on the F-16. However, maybe there is? Is there any protection at all, to protect the pilot, or any of its critical systems (flight control computers?)? If no armor, perhaps the flight computers (of which I understand there are multiple physical ones), are they placed in different locations in the aircraft to make it less likely they are all lost from damage in the same location?

As a bonus question, this philosophy of no armor at all on fast combat aircraft, does this extend to most other aircraft? If there are a few notable exceptions, it would be nice to have a couple of the noteworthy ones mentioned (not looking for an exhaustive list).


texts: If all aircraft were TCAS-equipped, how would this change ATC routines?

texts:
« The primary purpose of ATC worldwide is to prevent
  collisions, organize and expedite the flow of air traffic, and
  provide information and other support for pilots. » (source)

If all aircraft were equipped with TCAS, in what ways (if any) would this change ATC operation ?


texts: Do any airplane designs exist that don't involve a flight surface that provides downforce?

texts:
Most aircraft maintain longitudinal stability by balancing three forces:

The down force acting through the center of gravity (CG)
The lifting force acting through the center of lift
The down force acting through the center of pressure on the horizontal stabilizer.

My question is, what are some aircraft designs that deviate from this basic principle? Are there aircraft we see all the time that don't work this way? As a side note, how would weight and balance be affected if this principle isn't used?


texts: Are helicopters reinforced asymmetrically?

texts:
Helicopters are under a constant torque due to the action-and-reaction forces caused by the rotation of the rotor(s). In the tail rotor and tandem rotors configuration, the airframe is experiencing tension on one side and compression on the other. A weak airframe would be twisted by the strong torque produced by the rotors.

Are opposite sides of a helicopter airframe reinforced differently do due with the difference in stress?


texts:
What is this biplane?
What is this biplane shown above?


texts: What are the security measures preventing someone from chartering a 747 and using it to commit a terrorist attack?

texts:
While most travelers are well familiar with the security measures imposed by conventional airlines, it is unclear how they apply to private aircraft.

Is it possible for a private individual to charter a 747 for private uses? And if so, are there any security measures in place to prevent said private individual from misusing the aircraft?

(hopefully this question won't get me on the no-fly list) :)


texts: Does an Airbus A320 Navigation Display depict constraints for flightplans other than the primary?

texts: When any other flightplan (Missed Approach, Alternate, Temporary, Secondary) except the Primary flightplan is depicted on the ND in an Airbus A320 and the CSTR (constraint) button is pressed on the EFIS, will constraints for both flightplans be displayed on the ND?


texts: What is the source of emergency power for a 727?

texts:
I've found a couple of sources that state the 727's APU cannot be started while flying, as it draws air from the wheel well.

  It drew air from inside the wheel well, so it was only for use on the ground.

https://aviation.stackexchange.com/a/37715/34744

  The APU on the Boeing 727 can be used for ground operation only.

https://www.boeing-727.com/Data/systems/infoapu.html

Additionally, the battery on the 727 doesn't power all of the systems on the "essential bus", and presumably cannot start the engines.

http://cyberpilot.tripod.com/electrical_system.html

So what happens if you lose all engine power in a 727? How can the engines be restarted?


texts: Imagine that a helicopter raises its nose up and then there is a loss in speed. Can it enter a stall? If so, how do you recover from the stall?


texts: Do airlines black-list certain movies on their inflight entertainment system?

texts:
Do airlines trust the common sense of the responsible employee, when it comes down to NOT making certain movies available?

Besides excluding movies not appropriate for minors, are movies like United 93, Snakes on a plane or Alive officially a no-no?

Otherwise, without an official directive against these movies, aren't airlines risking a blunder and sparking an Internet storm?


texts: How do engine manufacturers derive varying amounts of thrust from a single engine model?

texts: What changes do manufacturers make to an engine to vary the amount of thrust it produces for different applications? Take the GE CF34 for example where there is a 10780lb difference between the thrust produced by the smallest CF34-3 and CF34-10E.


texts: What was the decibels level for the Sikorsky CH-37 Mojave Helicopter?   1956 --1959. I need this information for the VA, to process my hearing claim. I was a crew chief in the Army.


texts:
I have some confusion concerning the ground effect.
If we take two applications: Aircraft and Cars, they seem to have completely opposite effects.
Aircraft
From Ground effect (aerodynamics), we can read:

During normal flight, the upper wing surface experiences reduced static air pressure and the lower surface comparatively higher static air pressure. Flying close to a surface increases air pressure on the lower wing surface, nicknamed the "ram" or "cushion" effect, and thereby improves the aircraft lift-to-drag ratio. The lower/nearer the wing is vs. the ground, the more pronounced the ground effect becomes.

I can understand this, the air gets 'trapped' between the wing and the surface (and as consequence the pressure on the underside of the wing goes up)
Cars
However, from Ground effect (cars) we read:

Designers shifted their efforts at understanding air flow around the perimeter, body skirts, and undersides of the vehicle to increase downforce with less drag than compared to using a wing.
This kind of ground effect is easily illustrated by taking a tarpaulin out on a windy day and holding it close to the ground: it can be observed that when close enough to the ground the tarp will be drawn towards the ground. This is due to Bernoulli's principle; as the tarp gets closer to the ground, the cross sectional area available for the air passing between it and the ground shrinks. This causes the air to accelerate and as a result pressure under the tarp drops while the pressure on top is unaffected, and together this results in a net downward force. The same principles apply to cars.

The cross sectional area decreases, causing a higher velocity. This higher velocity decreases the pressure, causing the tarpualin to go down.
This confuses me, as it seems that the same situation (a plate in the vicinity of a surface) causes two completely opposite effects.
Both the "trapping air -> pressure goes up"  as well as "trapping air -> velocity goes up -> pressure goes down" explanation seem reasonable to me.
This made me wonder:
Why the ground effect has such a different outcome for wings and cars?
If I have a plate under an angle close to the ground, will the air be trapped, creating an air cushion pushing the plate up, or will the air accelerate, causing the plate to be pushed down? Does it have to do with some degree of area decreasing?


texts: What accidents have had crew accustomization to warnings among their causes?

texts:
A non-answer on this question claimed that:

  the idea that maneuvering with the stall warning activated will somehow damage us, causing us to ignore its warning when the chips are down and AOA is up, is just silly

which sounds wrong to me, as I vaguely remember reading about crews becoming accustomed to frequent warnings, spurious or real, and disregarding them when they became critical.

Which, if any, aviation accidents or incidents have had among their direct or contributing causes a crew that ignored a warning due to being used to it being spurious or unimportant?

I am looking for substantiated answers only, remember that this site is not a venue to speculate on aviation accidents.


texts: Do vapor clouds increase the radar scross section of an aircraft?

texts:
The F-22 is known for its stealth capabilities, which is mostly achieved with an extremely low RCS. Due to its high maneuverability we also see this plane often creating extreme vapor clouds while maneuvering:

Source: Wikipedia

We know that weather radar can detect clouds, so do such vapor clouds increase the RCS of the airplane?


texts: Application interview / career as a pilot: is qualifying from First Officer to Captain expected from an applicant?

texts:
I would like to know, if an airline expects an applicant, who wants to become a pilot, to qualify from pilot (FO) to captain (CPT)? Is qualifying kind of mandatory or is it primarily a personal decision?
I am asking because I do scientific investigation on pilot assessment. So if someone can share personal experience or even official articles and papers, I would be grateful.
EDIT: I have to add the background info, that the airline company is the provider of the apprenticeship (i.e. Lufthansa in germany).


texts: Is my understanding of subsonic inlets correct?

texts:
For subsonic aircraft like commercial jets, the inlet has the job of making sure the correct airflow is coming into the engine. Correct airflow is important for keeping the engine's compressor stage working. Too little or too much airflow will cause the compressors to stall and therefore no combustion happens. The inlet must keep airflow constant throughout the different stages of flight, including take-off, landing and banking.

The way an inlet ensures correct airflow into the engine is by slowing down the airflow and increasing the pressure. The inlet has a large volume which will decrease the speed and therefore will decrease the pressure. An inlet will work differently during low speed flight and high speed flight:

Low speed flight – During low speed flight including take-off and landing, the aircraft isn’t going fast enough for sufficient airflow to enter the engine. All engines have an operating design where they need certain airflow to work. To get enough airflow into the engine at low speeds, the engine's fan will suck in air. Air will be sucked in from a large area in front of the inlet. The streamlines of air will converge together as they get closer to the inlet. However, there is a location on the inlet where air does not move. At low speed flight, this stagnation point is on the outside of the inlet. This forces oncoming air to enter the inlet and not go around the engines nacelle. This provides the engine with enough air velocity at low speeds to operate efficiently.
High speed flight – During high speed flight the aircraft is going fast enough for sufficient airflow to enter the engine. However, allowing too much airflow will cause the compressors to stall. The inlet isn’t relying on the fan to suck in air from all directions. Air directly enters the inlet because the aircraft's velocity is fast enough. So to stop too much airflow entering the engines, the stagnation point moves further inside the inlet. This means that the desired airflow enters the engine, and the unwanted airflow flows around the nacelle.

Is this understanding of subsonic inlets correct?


texts: How does the 'quiet one' helicopter muffler work?

texts: Back in the Vietnam War era, special ops needed a quiet means of inserting soldiers behind enemy lines to install eavesdropping equipment. They modified a Hughes 500 to do the job. One of the things done was the addition of a muffler to the jet exhaust. How did it work? It looks very different from the lobes and serrations used to quiet the cores and fan exhaust in turbofan engines.


texts: Why B-52 engines produce lots of smoke only during take-off?

texts:
During the flight it seems there is no smoke, it's only during takeoff. Here is an example

This question explains that smoke is caused by unburnt fuel but why is there so much more during takeoff?


texts: What is the purpose of several mandatory stops (RWY AHEAD) at busy airports?

texts:
I learned that red signs mean: full stop is mandatory.

Do aircraft have to stop before CAT III 08L sign AND before CATI 26R-08L sign?
What is the purpose of making two stops?
Is the area between these two mandatory stops special?


texts: Should you wait to switch to the ground frequency until after crossing a runway?

texts:
I've never had the opportunity to fly into a controlled airport with parallel runways, so I've never actually faced the situation. But, in the interest of being ahead of it, when would it be prudent to switch to ground frequency with this clearance (assume I just landed)?

  N12345, right on E, cross 27 R, contact ground .9

Should I call ground (or switch frequency, so I no longer hear the tower) before or after crossing 27 R? My by-the-book assumption would be immediately, as there's no "then" or "after crossing" or similar, but somehow that feels wrong. I suppose normally it doesn't really matter, but in the case of someone (which includes me, everyone makes mistakes) doing something wrong, where would they call me as I'm about to cross 27 R?

The reason I ask is that I saw exactly this case in a YouTube video quite a while ago (can't find it anymore though), where exactly this happened. The pilot was narrating for the video and stated he'd switch frequencies "now that he'd crossed the runway", at which point I started thinking about it.

Considering the situation, I would probably rather wait since there's an inherent delay when switching frequencies anyway, I might as well wait a bit longer, but knowing myself, if I hadn't thought about it ahead of time I'd probably switch right away. The only reason I can think of for saying it this way is if 27 R is not an active runway, but then again, reality does not always match what's in the book.


texts: How would I calculate CG in this practice problem?

texts:
As I'm studying PPL theories, I've encountered with this kind of a question below and it would be great to understand the principle behind the calculation of the 'CG'

Calculated take-off mass = 2300 lbs, calculated CG = 95.75 in, fuel burn = 170 lbs on station 87.00 in.
Where is the CG situated after the landing?


texts: What are the ways to keep the birds away from airfields?

texts:
I know bird strikes are a major issue for many airports, and that measures are taken to keep birds away.
There are some obvious things airports can do like not to have any stray garbage, food, etc. in the open, but I'm sure other less obvious methods are also used.

What exactly are some of the widely used techniques to keep birds away from airports?


texts: How can I best prepare for my first lesson on stalls?

texts: I am a flight student preparing to practice stalls and stall recovery in a Tecnam P-2002. I have already done spin recovery. On top of that, what preparation techniques have others found useful?


texts: How do missiles steer (mainly air to surface)?

texts: How do missiles steer in the air? What techniques do they use?


texts: What methods are used for calculating maximum takeoff windspeed of a helicopter?

texts:
I would like to calculate the maximum windspeed in which a helicopter may safely take off and safely land, assuming a theoretical wind environment with constant wind direction and no gusts.

I understand that Effective Translational Lift is generated when taking off into the wind, which increases the climb rate.

However, I would like to understand at what windspeed taking off and landing into the wind is theoretically no longer possible for a given main rotor RPM.

Some factors I have considered include:

while the main rotor is spinning at less than flight RPM, and nonrigid, that it may come in contact with the fuselage.
during takeoff or landing: if the vehicle must pitch forward to compensate for extremely strong headwinds while inches above the ground, the main rotor may strike the ground

While not relevant to the theoretical wind environment described above: if there are gusts, I have also considered:

during takeoff or landing: while hovering inches above the ground, a strong crosswind may roll the vehicle above a threshold which causes the main rotor to strike the ground.

What methods might I use to calculate these (and any other factors I have not considered) precisely?


texts: How were fighter jets built in the 1950's?

texts:
As far as I know, jets did not see mass production across the world until the 1950's. So I'm interested in how they were built in that time. How many different types of factories were needed? How did those factories work? What supplies were needed and how much manpower did they need per jet?

Right now I'm only imagining two kinds, an airframe factory and an engine factory. I'm very interested in learning more and would not be surprised if there are many other types of factories that go into making a fighter jet.

For simplicity, let's exclude electronics factories like the radar, and weapons factories like guns, bullets, and missiles.


texts: Can I get pop-up IFR clearance to waypoint (intersection)?

texts:
Let's say I departed from the airport to fly to the practice area (VFR).
However, there is a thick cloud layer between where I am at right now and practice area. I already got a report that practice area is clear and VFR.

To go through the cloud, I need to request IFR to go through the cloud.
At this point, can I request pop-up IFR to any waypoint (as a destination) that is in practice area?

Will I be able to cancel that IFR flight right after I go through the cloud and when I am not in IMC?


texts: What is a fuel tank float valve and how does it work?

texts: This report on dodbuzz mentions a 'fuel tank float valve'. Neither google nor StackExchange seem to know what it is. What is it, why is it necessary?


texts: What is the difference between EPR and rotor speed as thrust setting parameter?

texts: Amongst various thrust setting parameters, Engine Pressure Ratio (EPR) and fan rotor speed are two of them. Does anybody know why GE uses fan rotor speed and P&W uses EPR as thrust setting parameter?


texts:
A secretive space catapault is said to be in progress.  For the sake of mathematical simplicity, assume the launch vehicle is one kilogram point-mass and to be placed in geosynchronous orbit.

What quantitative forces (impulse?) and energy necessary to accelerate said vehicle into geosynchronous orbit?  Feel free to make any assumptions necessary to facilitate an answer.


texts: Why can the A-10’s engines flame out merely from ingesting smoke from its gun?

texts:
Apparently, firing the A-10’s GAU-8 cannon can sometimes cause its GE CF34 engines to flame out from ingesting the smoke from said gun.

It’s easy to see how the gun’s smoke could be ingested by the engines:

(Image by 67blackcherry at The Gear Page, via @Koyovis here at avSE.)

Even when the gun is firing and its smoke is blowing into the engines, though, the vast majority of what’s going into the intakes is still air; even though it is true that, to quote Wikipedia, "[g]un exhaust is essentially oxygen-free", this exhaust is immediately forced into (and diluted by) ambient air the moment it leaves the barrel, and is blown back towards the engines (and diluted still further) by yet more air.  And modern high-bypass turbofans like the CF34 are - indeed, have to be - designed to keep running even when quite a considerable proportion of the incoming air is not, in fact, air (I think I remember reading somewhere about small high-bypass turbofans being tested, successfully, for their ability to keep running when given a half-and-half mix of air and rainwater, although it’s possible that I might be misremembering).  So how can gunsmoke ingestion be enough to flame out the A-10’s engines?


texts:
For airliners, under which meteorological conditions is de-icing required?

What factors (temperature, humidity, dew point, precipitation, etc.) influence the decision to de-ice?

Is decision to de-ice down to regulations, the airline, or the captain?


texts: What would happen if a helicopters rotor hit the [in-air] refueling probe?

texts:
My first guess is that they would catastrophically fail - but I also read the Eurocopter Cougar has propeller blades that will withstand the impact of a 20mm round (I'm guessing other military helicopters are similar).

Is it likely that the probe could bounce off or is it a pretty much guaranteed byebye scenario?

Also could the rotor become entangled in the hose or would it simply slice it?


texts: Why keep the doors open for aircraft in boneyards?

texts:
Photo by Bastian Ding from airliners.net

The image above shows Boeing 747s stored in a boneyard.

Why are the aircraft left with the doors open? Won't this increase the probability of further damage and/or faster corrosion?


texts: If the profile of a wing pulls a plane up, why can planes fly inverted?

texts:
I'm simplifying here, but every introduction to flying shows us that the profile of a wing leads to lower pressure on the upper side of the wing, hence the wing and the plane attached to it will be pulled up.

All right.

How does that explain a plane flying inverted? If the explanation was right, the plane would pull itself towards earth.


texts: Switching careers from physics to aviation

texts:
The main question is whether the background in the (scientific) field of applied physics and engineering can help one to start a career in aviation (to do it for living)?
It seems impossible and not worth trying, because it looks like many airmans start flying from the very beginning of their lives. After 15 years in the air they are (al least looks like) mature pilots that would be chosen to be hired somewhere instead of "that freshly switched street bum".
On the other hand, that sort of fundamental education and some years of work in the field may pose some advantage. Does it, really? If yes, how can it be exploited?