texts: Do regulations permit an airliner be equipped with a radio transmitter which cannot be controlled by the crew?

texts:
In response to the case of MH370, an idea which has been floated is that of a device to transmit an aircraft's GPS position. Not specified is whether such a device would be operable by the flight crew.

Among the scenarios suggested to account for the aircraft "going dark" and its apparent flight path is intentional action by someone aboard.

To provide aircraft position (or any other parameter) reporting free of any possible interference by anyone aboard the aircraft would require installation of equipment inoperable by and therefore in a location inaccessible to anyone (crew included) during flight. That means such equipment could never be powered down while the aircraft is in flight.

Have there been/are there currently any regulations which would prohibit the installation of such a device for any reason - e.g. fire safety, possible interference with other radio equipment essential to safe flight (navigation, communication)?


texts: What units are used for the horizontal grid lines on a sectional?

texts:
On a standard 1:500,000 aviation sectional chart, the map is broken down into quadrangle "sections" with a maximum elevation figure printed in blue in the center.

Using a chart-plotter I can see that the vertical (north-south) grid lines printed on the chart are in units of nautical miles.  Each quadrangle is 30 nautical miles vertically, and roughly 20.5 nautical miles wide (west-east).

What's confusing me is that the scale printed on the horizontal portion of the quadrangle section doesn't appear to be in nautical miles, statute miles, or even kilometers.  What does the horizontal scale represent?  Is there a unit associated with the horizontal grid?


texts: Are there any best practices for transitioning from paper logbooks to electronic logbooks?

texts:
I've started flying again, and some of the things/places I fly are more interested in time in type than my old paper log shows. I'm considering going to some form of electronic logging (currently for Android and/or Linux but likely moving to iPad next year for EFB compatibility).

Question: When I start up with a new program, do I merely summarize my flight experience and ignore the tail number and a/c type? I've flown a few different birds in my time, and trying to go back through 3 logs and setting everything correctly would be a royal pain.


texts: Why isn't there a procedure for dual-engine failure in twin-engine airplanes?

texts:
I'm licensed to fly multi-engine aircraft. I currently fly the DA-42NG.

However, nowhere in my training and in the official POH was I introduced to procedures for handing a dual-engine failure in-flight.

There's no mention of a Best Glide Speed whatsoever.

I'm assuming this is the case for most, or maybe all GA Twin-Engine airplanes. I know jets can glide for some time without any power.

Question is - can GA airplanes? I know it won't fall like a rock - but there's got to be some science to follow here, right? Why haven't the manufactures mentioned it even once? Why isn't it part of the training?


texts: What is the purpose exactly of a ‘Control Check’?

texts:
I recently watched an Air Crash Investigation episode where Qantas flight 32 lost an engine shortly after takeoff. It was revealed that a stud pipe in a Rolls-Royce engine was made incorrectly, causing the pipe to snap and burst through the engine and the aircraft's wing, severing major hydraulic systems, and causing the ECAM to display pages and pages of errors.

On the final approach, the captain announced he wished to perform a ‘control check’.  He said (and this is approximate):

  When the aircraft is damaged, you have to certify it is safe to land before you try to land.

I assume this is so that the captain can make the necessary preparations if he feels his aircraft is not safe to land. On flight 32 this was done by moving the stick left and right to simulate lining up with the runway.

Perhaps a better question is back to the post's title.

What are the purposes of in-flight Control Checks?

In my example of Qantas Flight 32, the stick was moved left and right on final approach to simulate lining up with the runway. This was only small left and right control deflections.  The flight deck had only minutes until landing.  What was the captain expecting to see, or not to see?  Can the captain after that brief manoeuvre be aware of his aircraft enough to make a decision?

Does this mean then that a Control Check only comes, or should only be done, if you are worried that the aircraft cannot land?  Can it be done at any other time?  In other words: is an in-flight control check only done for landing?

SOURCES:

Wikipedia
Flight 32:
https://en.m.wikipedia.org/wiki/Qantas_Flight_32


texts: What is the "compression ratio" of air hitting the nose?

texts:
Sorry but I don't know how to accurately phrase this question. I want to know how much compression results from air hitting the nose of an aircraft.

I'm interested in the traditional airliners (Mach 0.85, blunt nose, like B747 or A320), as well as the supersonic stuff like Concorde and even Mig-31.

Is there an equation for this? Presumably with cross section area and some kind of coefficient of form drag. I'm looking for a density and/or pressure change.

I want to know if this is significant, like if the aircraft actually has to do a lot of extra work to overcome the greater density in the nose air. But there are actually several reasons. I want to calculate how much heat arises from the adiabatic compression, which will let me know if some kind of active cooling is required for a given material. I want to know if the increased density of the nose air actually changes the general drag equation, like if you have to put in a higher density value when just calculating the fuselage drag. I want to know what possible boost you can get from the "ram effect" such as from a ramjet.

In this question, all I'm really asking for is the compression ratio...or change in density, or change in pressure...sorry I don't know which one is more accurate. If I just have that, then I think I can answer the rest using other equations I know of.

I wanted to explain myself in case this appears too broad or too xyz thing, sorry can't remember that term either. Hopefully someone will know an equation that can answer this. Equations give hard numbers, so they're always better than relative adjectives like "larger", "negligable", etc.

Also, if someone can suggest tags, please do so. Couldn't think of anything better than "drag".


texts: Why do modern aircraft tend to have angular tails?

texts:
In the WWII-era and earlier, many (most?) planes had rounded tails, even high-speed and high-performance fighters such as the Bf 109 K, Ta 152 (though it is more square-ish), P-38, Hawker Typhoon, and even the F-80. A notable exception to this trend is the P-51.

Modern aircraft, on the other hand, tend to have very angular tails. High speed fighters, to airliners, even relatively slow aircraft like the Cessna 152 or Piper Archer have very angular tails.

What is the reason for this change in trend?


texts: What is "50 ft obstacle climbing speed"?

texts:
Vy and Vx make sense to me. They are used for fastest height gain at a given time and biggest angle of climb. But what is the purpose of that speed (it's from DA20 POH)? It's only 3 kts faster than Vx.

thanks!


texts: Why is the 787 tail cone made out of titanium?

texts:
In this question there is a drawing of a 787 that shows that the tail cone is made of titanium.

Why is such a heavy-duty material like titanium required for the tail cone?

I do not see how there could be any significant loads or reasons for excess temperature there.


texts: How much horsepower to weight is required for a 1:1 thrust ratio?

texts:
I did a math experiment today, but wanted to verify the results.

I wanted to figure out how much horsepower is needed for an aircraft to hover in midair with no wings/lifting body (1:1 thrust/weight).

So to start I found that a unit of horsepower is the amount of work required to move 550 pounds 1 foot every second.

Then I wanted to find out how many foot/pounds of force gravity places on 1 pound of material. With a static acceleration of 9.8m/s (32f/s), it seems that 1 pound has 32 foot pounds of gravity acting on it.

Now for my equation:

Hp = 550 (f/p)
Gravity = 32 (f/p)
Hp / Gravity = 17.1875

So it seems 1 hp can hold 17 pounds in the air, but to incorporate propeller inefficiency, I just used 70% of that. This leaves me with 1 hp being able to vertically lift 12 pounds when accounting for the inefficiency of a propeller.

Is this a relatively correct assumption? I know thrust changes as the aircraft accelerates, but in a hovering state the acceleration is 0 f/s as a whole. So will these numbers apply?

Edit: I initially used a specific ultralight to prove how high the numbers were, but I used wrong data from the spec sheet. So I removed that reference from my question.


texts: How can an aircraft travel faster than speed of sound without breaking the sound barrier?

texts:
An excerpt from the BBC article here https://www.bbc.co.uk/news/uk-england-london-51433720

"Despite travelling faster than the speed of sound the plane would not have broken the sonic barrier as it was helped along by fast-moving air."

Could someone please elaborate on how that is possible?


texts: If we add a video recorder in the cockpit to complete FDR/CVR, will we add a blackbox?

texts:
The introduction of a video recorder in addition to the current audio and flights parameters recorders used for crash investigation (CVR and FDR) is suggested by this article (published in the New York Times in 2004) citing officials of the National Transportation Safety Board, and called image recorder in a most wanted list (published in 2012) of the FAA.
Those two references shows the introduction of a video recorder is taken seriously. I don't want to debate whether this is usefull neither what should be recorded (wide angle of the whole cockpit, close view of switches and screens, black & white or color, ...).

Given the answers of this questions, the video track record's requirements should be very close to the one of the CVR, thus adding this track to the CVR seems reasonable.

If we add this video track to all tracks recorded by blackboxes, will this records to an existing blackbox (either the FDR or the CVR) or will we create a dedicated blackbox (resulting in three blackboxes)?

related questions :

Why could increases in cockpit voice and image recording potentially raise privacy concerns?
Why doesn't the black box also record video?


texts: What requirements are there to fly into KDCA?

texts:
In the A/FD for KDCA, it says:

  NOTE: See Special Notices — District of Columbia Ronald Reagan Washington National Airport.

I know that there are special restrictions for flying into DCA, but where is this "Special Notice" that they are referring to, and how can I get permission to fly into DCA under Part 91?


texts: Can a helicopter really fly with rotors going this slow?

texts:
I was watching this youtube video and I noticed that at 3:17 seconds they show a coast guard helicopter rescuing a man from a ship. Whats shocking about this is that the main rotor of the helicopter seem to be going incredibly slowly and the tail rotor has completely stopped.

How was the helicopter able to stay flying with such a low rotational speed? Was this some optical illusion or was the rotor really spinning that slowly?

Also, how was the helicopter not spinning? From what I understand the main purpose of the rear rotor is to counteract the rotational force of the main rotor. Since the rear rotor wasn't moving, shouldn't the helicopter developed a spin counter to the spin of the main rotor (even though it was slow)?


texts: Means of protection against hunter-killer UAVs

texts: I would like to know all existing technological means of defending an area against the MQ-9 Reaper or other hunter-killer unmanned aerial vehicles (UAVs) used by the United States in countries like Afghanistan, Syria, etc. Such means should either force the UAVs to leave the area or crash.


texts: Should I contact ATC if I don't have a transponder?

texts:
The flight school I usually rent from is under the shelf of class C airspace. If you're going out to a practice area, the standard procedure is to contact approach control and get a squawk code, so they can better coordinate traffic. However, it's not required, since the practice areas are outside the class C.

At the moment, none of the school's planes have transponders*. One of the instructors said not to contact approach for now, because without a transponder, they wouldn't be able to do anything anyway and it'd just annoy them. On the other hand, during my last practice flight, I heard** them vector an aircraft around some unknown other aircraft. I suspect the unknown aircraft was me, which made me think that it would be better to talk to them after all. That way, I could (for instance) tell them my altitude, and they wouldn't have to vector an aircraft that was (say) 5,000 feet above me. But, back on the first hand, if I'm just a primary contact, they have no way of knowing which blip is talking to them, so maybe they'd have to vector the traffic anyway.

So, in that situation, is it better to contact ATC or not?

* Since this came so soon after the switch to ADS-B, and since it affects all aircraft at the flight school, I rather strongly suspect that they just got a bad batch of ADS-B transponders and had to send them back. That's just my theory, though, I don't know for sure one way or the other.

** I tuned in the approach frequency, even though I didn't contact them.


texts:
Are anti-icing systems needed for any missile carried by a small combat jet? And if so, how is this achieved?
I realize of course that missiles typically fly at Mach 2.5+, so the compressive effects will heat the air around it. However, a jet is typically carrying the missile under its wing, and can be fighting at subsonic speeds. Flying through clouds or rain, or high altitude subsonic dogfight, are very ice-prone situations. If the missile has iced up and then is fired, it could fail.
Moreover, even at supersonic realms, there are other parts of the missile besides the nose and leading edges.

Top wing surface, if it gets iced, will affect the camber and lift.

Trailing edge of a control surface.

Main body could theoretically get too heavy with ice.

Seeker head could ice up at any time before firing, and if not ready, will prevent lock on.

I highly doubt the inside of the missile will be hot enough to cover all those areas, especially the nose and wings. So do missiles need anti-icing, and if so, how is it achieved? If not, why not?


texts: Why do only some aircraft require tail anti-icing?

texts: Why do some aircraft require anti-icing on the tail while others (Dassault Falcon Jets, Boeing 737, 747, etc.) don't?


texts: What license is needed to fly the electric "Volocopter" helicopter?

texts:
Here is a video of the aircraft in flight.

The Volocopter Looks like it would fly quite differently than a helicopter. Is that true? Does that matter? Is it still a helicopter license that's needed?


texts: Do contra-rotating propellers have the same RPM?

texts:
Image source

Here is a contra-rotating propeller. The front propeller rotates counterclockwise while the back propeller rotates clockwise. My questions are:

Do they rotate at the same speed (RPM)?
If not, which one is rotate faster, and why?


texts: Are there any examples (real life cases) of invalid FMS data affecting flight operations?

texts:
Do you know of any real life cases, when invalid FMS data affected somehow the flight operations?

By invalid FMS data I mean a case, when the procedure coding does not reflect properly the original procedure as published by state's AIP service.

Related question: What happens with RNAV procedures on the way from AIP publication to FMS database


texts: What is the ATFM Project BOBCAT and why is it important?

texts:
Aerothai, the ANSP of Thailand, runs an ATFM Project called BOBCAT (Bay of Bengal Cooperative Air Traffic Flow Management System).

Why is it so important? And why is an ASNP from Thailand running a project, that spans across most of South Asia?


texts: What is this plane approaching an airport in Asia? (Also, what is the airport?)

texts: The airport is in Asia, that is all I know.


texts: Is it considered good or bad practice to raise the flaps right after touchdown?

texts:
This question is about light, tricycle, single engine aircraft.

I have made it a habit to raise the flaps right after touchdown (when the nosewheel is on the ground). My instructor used to do that every time during initial training so I took over the habit.

It makes sense to do this for the following reasons:

better braking performance because lift is reduced while rolling out
less crosswind effect, reducing the risk of loss of directional control after landing
(less important) it's part of the after landing checklist, so when it's done, it's done

However, I was recently checked out on a C182 that I wanted to rent in Florida and when I raised the flaps right after touchdown the instructor shouted "what the < beep > are you doing? You should never raise the flaps until you've turned off the runway". He couldn't provide a good reason though, so when I told him about the things I listed above he simple mumbled something about keeping my attention on the runway instead of fiddling with the flaps lever (which is a something I don't even have to think about)

My question is: Is it really a bad idea to raise the flaps that soon after landing? Or is it actually a good habit?

(I noticed that most airliners also wait until they're clear of the runway, but these jets have spoilers to get rid of all the lift)


texts: Is there a generic term for origin and destination seen from an airport point of view?

texts:
I am trying to create a program that gives you the departures or the arrivals from a given airport.

Thus, in the software code, I would like to refer to both origin anddestination with the same term, in order to print the former if the user requested arrivals, and the latter if the user requested departures.

So basically I want to know if there is a common name for these two terms, when speaking from the airport point of view, i.e. referring to a generic flight, regardless of it being inbound or outbound, what is "the other airport" in the jargon?


texts: Where can I find the full report of this controlled F-4 fighter jet impact?

texts:
I found the following video on YouTube

They used an F-4 Phantom jet as a test article in a crash into a concrete wall at 500 mph. It wasn't actually a crash because the plane was not flying.

I would like to know the disposition of the components of the aircraft if possible. Since this was actually a materials science test and not an aviation test, I am unsure if that even exists. Where can I find the complete report of this controlled impact?


texts: Process for Compensator in Altitude Hold

texts: Trying to understand autopilots on a technical level. When making an altitude controller there is a compensator Gc that is used to acquire a Pitchcommand which is passed to an attitude controller (the attitude controller uses a PID loop which I understand). What is the process of creating that compensator? I've read that a PI compensator is less reliable and more complex than a lag compensator. But as a rough approximation (still trying to figure it out) of what needs to be done for a lag compensator you need to have a linearization of the aircraft model, apply root locus, adjust poles, and acquire a transfer function. If anybody could specify what would need to be done (correcting my missing/incorrect understanding) that would be very appreciated.


texts: What does it mean for a plane to be aerodynamically stable?

texts:
I've heard that most planes (excepting fighter jets) are "aerodynamically stable." What does that mean?

Let's say you're cursing around in a Cessna 172 without autopilot, and you take your hands off the controls. What happens?

Will the plane stay at the same pitch and avoid stalls and dives?
Will it stay at the same altitude?
Will it say at the same heading?
Will it correct each of these as the plane is buffeted by turbulence?


texts: How can I acquire an N number that's showing as deregistered?

texts: I'd like to use an N number that is listed as available. But when I request it, it shows as being deregistered. How can I get this number for my aircraft?


texts: Is it possible to fully utilise excess heat from an aircraft to power other systems required for the aircraft to function?

texts: Is it possible to fully utilize excess heat from an aircraft engines to power other systems required for the aircraft to function, using heat exchangers and other clever engineering tools and techniques? This would seem to me to amount to massive energy efficiency and fuel savings.


texts: What is the procedure to enter, maintain and recover from a flat spin?

texts:
Looking for a play-by-play from the pilot's seat of a Pitts biplane. What thoughts, considerations and control inputs are required to enter & maintain a flat "pretty" spin and a calculated exit path?

Visual example:
What is going on in this guy's head, his hands and his feet?


texts: Does the AP disengage if the plane is upset and how would the flight controls react if not being held?

texts:
Does the AP (autopilot) essentially detect a rapid change in speed/altitude as a wild maneuver? If so, upon disengaging, if the pilots are not holding the control column in a neutral position, will it move in whatever direction the plane is going?

For example, a steep climb that wasn’t anticipated, and no one holding the Column, will it fall back towards the pilots, ultimately making the steep climb worse?


texts: How are the BNR and BCD data formats identified in an ARINC-429 message?

texts: I'm a newbie in ARINC-429 standard. How does the receiver identify which data is in BCD format and which is BNR? I understand that labels indicate the message data carried information, but it does not indicate if the data is BCD format or BNR. If my understanding is correct, the BCD or BNR format used is dependent on the equipment ID. And that leads to my next question: how is the equipment ID embedded in the message?


texts: Why are almost half of the world's helicopters in North America?

texts:
I was reading this report and came across the following quote:

  North American purchase plans [for civilian-use helicopters] are a significant component of the overall 2017 survey demand, as the region represents more than 40 percent of the current world fleet.

I don't know a ton about the helicopter industry, so this quote surprised me.  What are most of these civilian helicopters in North America being used for?  More specifically, in North America what are the uses for helicopters that aren't common in other parts of the world?  Does this unique demand come mostly from offshore drilling, police, or medical usage? Why don't they use helicopters for those purposes in other countries?


texts: What is the difference between Line-Replaceable Unit (LRU) and Integrated Modular Avionics (IMA)?

texts: I'm studying the Integrated Modular Avionics (IMA) and the Line-Replaceable Unit (LRU), but I don't get the difference.


texts: What happens when an airline pilot decides not to fly at the last minute?

texts:
What happens when a commercial airline pilot wants to remove himself from a flight a short time before takeoff (say an hour or less)? He obviously can't be forced to fly, and there may be very good reasons he shouldn't.

What is the penalty for the pilot?
What are the passengers told if it is something embarrassing, like a drunk pilot?
How long does it take to get a replacement pilot?

Surely the exact answers depend on the airline, but in general what happens? What regulations govern this situation?


texts: Does slipping in turns allow higher climb rates?

texts:
Sailplanes, among others, use a cotton string to show the sideslip angle. I've often heard that while circling in thermals the cotton string should show a slight slip angle to climb faster. This effect can be observed specially at high bank angles with heavy, high span gliders like the ASH-25. The german skid Wikipedia-article has even a subsection about it; however, without references. Flying like this has also the advantage of lessening the stall risk of the inner wing.

Is the indicated sideslip angle of the cotton string real or only apparent and due to the uneven incident airflow? Has this effect ever been scientifically measured and is it used in larger airplanes with FBW and sideslip angle sensors while turning?


texts:
A hybrid airship generates lift from a combination of lighter-than-air buoyancy, and aerodynamic lift.
Some figures suggest that up to 40% of the lift comes from aerodynamic lift (wikipedia). So how does a fully laden hybrid airship achieve vertical take-off? If the airship weights 100 tons, and it needs to get 40% of it's lift from aerodynamic lift (requiring forward movement) then that's 40 tonnes of lift that needs to be provided from somewhere whilst the aircraft is accelerating to flying speed. Where does this come from?
My guess is that a hybrid aircraft can only achieve full load when operating from a conventional airstrip, and that vertical take-off is only an option when operating at 60% load capacity. Is this correct, or have I missed something?


texts: What is wing trammelling and how does it affect wing stability and performance?


texts:
I am planning on making a pair of rudder pedals from scratch. I don't know whether they should be hinged, or slide forwards and backwards.

On real aircraft, how do they work? Does it vary from plane to plane?


texts: Why do ADS-B outages occur without simultaneous RAIM outages?

texts:
If you check the ADS-B prediction tool and the RAIM prediciton tool on SAPT.FAA.GOV you will see far more ADS-B outages.

What causes ADS-B outages to occur at different times than RAIM outages?  Are ADS-B stations shut down for maintenance?  Is it due to the local weather? or something else?

I know ADS-B systems are reliant on the Global Positioning System to determine location to send in the squitter, so I am assuming that a loss of RAIM is one reason for an ADS-B outage, but what else is causing the additional ADS-B outages not simultaneous to RAIM outages?


texts: What does a "hard stand departure" mean?

texts:
I am reading a table explaining how to plan multiple diversion returns from an individual station:

  widebody gate departures - xx minutes
  narrow body gate departures - xx minutes
  all hard stand departures - xx minutes

I am not a native English speaker and do not understand what a "hard stand departure" is.

Could anybody please explain this term?


texts: Why does the F-16 have a fixed stabilizer section inboard of the stabilators?

texts:
So, we have a F-16 chilling on the ramp, showing us its tailfeathers:

Interestingly enough though, inboard of the all-flying stabilator sections, there is a fixed stabilizer section (this is quite clearly visible on the right due to what the stab is doing on that side).  This isn't universal on stabilator-equipped aircraft though, or even fighters, as the F-22 appears to have its all-flying horizontal tail hinged at the fuselage joints:

and the trimmable stabilizers on airliners are hinged at the fuselage-stabilizer joint as well:

So, why is it that the F-16 doesn't follow this pattern? Is there some aerodynamic design reason for that?


texts: Should you immediately attain max glide speed after engine failure?

texts: For the Cessna 172 Skyhawk maximum glide is attained at a speed of 65 KIAS. If you're flying well above this speed, let's say 90 KIAS, and suffer an engine failure, what would be the best practice: immediately slow down in order to achieve 65 KIAS as soon as possible, or slow down slowly?


texts: Do pilots who have color deficient eyesight see light gun signals differently?

texts: Can pilots with color deficient eyesight expect to see the red, green, and white light-gun signals as such? In other words, if the controller is giving them a green light, will they see green? If they are being given a white light, will they see white?


texts: I want to know whether the elevators generate vortices like the wings do? If yes, then where do the vortices form?


texts: What happened to the blades in this picture?

texts:
Here is the picture

Source:(brians-travels.com)

This looks like a photoshopped picture, but I believe it isn't. Is this some kind of strange occurrence that occurs only with the human eye? The blade on the top looks bent downwards. I can't figure out what happened in this picture. And will your picture look like this every time you take a picture of a fast moving propeller?


texts: What is the purpose of a dorsal fin such as on the Boeing 737?

texts: I've noticed that the 737 has a rather unusual vertical stabilizer, with an extension at the front. Is the 737 the only plane equipped with such a vertical stabilizer, and what is its purpose?


texts: What role do the winglets on the next-generation 737 play?

texts:
I've flown on a couple of 737's recently and noticed that the wings are quite beautiful and have a distinctive upward sweep at the wingtip, almost like a vertical stabilizer.

What advantages and what disadvantages (if any) does this type of wing provide?  I imagine there is some gain in overall stability.


texts: What is significant about the number 8069 ft?

texts: On a sectional chart legend, the airport icon with a solid magenta or blue disk is labeled as "Hard surfaced runways 1500 ft to 8069 ft in length".  This seems like an extraordinarily arbitrary number to use as the upper limit before a different symbol is used.  When I convert this to meters, or yards, or furlongs, or any other common unit, it doesn't correspond to any even number so it doesn't seem like a conversion from another system of units.  What is the reason for this unusual dimension for a runway length?


texts: Can a plane with 2 sets of shorter wings fly?

texts:
I am proposing a plane that has 2 short wings of the same size on either side of the fuselage (two in the front and two in the back). Rather than using the horizontal stabilizer to destroy lift, the wings in the back help create lift and adjust the pitch of the plane.

One problem that I thought of is the wingtip vortex created by the front wing hitting the back wings. I'm guessing this can be resolved by placing the back wings higher than the front wings (from a front view of the fuselage).

Could this work?


texts: Why are biofuels usually blended with standard jet fuel when used?

texts: When biofuels are used in both demonstration and commercial flights, it is common for them to be mixed with standard Jet A fuel. Is this due to safety reasons, cost or due to specific properties (e.g. freezing point of biofuels) that may not enable them to be used solely all the time?


texts: Which US airport has the lowest circling MDH?

texts:
As I recently contemplated 14 CFR 135.223 and its implications, I began wondering about airports with exceptionally low circling minima.

For a little context and background, the part of §135.223 that sparked my imagination is the following exemption clause:

  (1) The ceiling will be at least 1,500 feet above the lowest circling approach MDA

This got me thinking along these lines: "How often might one encounter both a circling MDH sufficiently low as to allow exemption from the fuel requirements of §135.223(a) and a ceiling high enough that the requirement of §91.169 to file an alternate airport remained in effect? Such a scenario would require a reported or forecast ceiling of 1900 ft and a circling MDH of 400 ft or less.

I know that there are at least a few airports with MDH of 400 ft or lower (which seems altogether too low). Thus, my question is:

Which airport in the United States has the lowest published circling Minimum Descent Height (MDH) for an instrument approach?

I initially wanted to apply this question equally to any airport worldwide. However, I have chosen to limit the scope of this question for two reasons.

Firstly, ICAO standards are more strict in this area than the TERPS standards that the US, Canada, and a few other parts of the world adhere to. Specifically, the TERPS standards for Cat A prescribe a minimum MDH of 350 ft, while ICAO prescribes a higher minimum of 394 ft.

Secondly, I recognize that discovering an ultimate answer to this question (i.e., "ABCD airport definitively has the lowest circling MDH") is difficult, especially if the question's scope included airports from multiple nations. For this reason, I have chosen to limit the scope of the question to the United States of America, where available databases should provide an opportunity for a definitive answer.

For example, the lowest MDH that I know of is Point Hope (PHO/PAPO) with a circling MDH of 361 ft for both the RNAV RWY 1 and RNAV RWY 19.

While this might be the lowest published MDH, I don't know whether or not it is.

I am looking for any answer that can factually establish which airport has the lowest published circling MDH, whether that might be Point Hope or some other airport.


texts: Why does the F-111 sometimes squirt a giant fire plume behind it? (NOT afterburners!)

texts:
As seen in multiple pictures:

First, this one, it appears the aircraft is spraying copious amounts of fuel into the exhaust!

Surely this provides no thrust, not in the way an afterburner (which the F-111 has!) does.

Is it perhaps as an alternative to flares for anti IR missiles? It seems logical, but I don't think so, because I've seen it on takeoff too!

At any rate, it is QUITE badass!

EDIT: YouTube video!

EDIT: Can any other aircraft perform this?


texts: Which should I get a FAA glider licence or a Canadian glider licence?

texts: I plan to operate in the Caribbean (Antigua, under ECCAA jurisdiction, which does not have a glider rating of its own) and not in the USA or Canada. I am looking at which one would be require less work and time on my side. I plan to give rides in my country and practice the sport.


texts: Are there general accuracy requirements for aircraft power supplies?

texts:
Let's say I have some LRU device that requires some DC voltage to be powered on. Are there any general requirements in aviation/aerospace that say how accurate that supply voltage must be in order to be allowed on a plane?

Update:

To be more specific, consider an LRU that takes 28V on the input and provides it to a DC-DC converter. I would like to know how accurate that 28V being provided, needs to be.


texts: What is the definition of load factor and how do you apply it?

texts:
I'm a little confused about the definition of the load factor, n, as the definitions I found seem to contradict its application in force and moment balance analysis of an aircraft structure.

The definition given in my university script states that the load factor equals the ratio of all external forces acting on an aircraft minus its weight, to the magnitude of the aircraft's weight; this implies that the load factor is the ratio of all aerodynamic forces acting on an aircraft to the magnitude of its weight.

The Wikipedia definition of the load factor states that the load factor is the ratio of the sum total of all aerodynamic forces acting on an aircraft to its weight.

My script definition therefore tallies with the Wikipedia definition. All good so far.

Now, however, there is also a sentence in my script that states that the load factor is a means of including all inertial loads and gravity loads in observing the loading of an aircraft; this implies that weight is included in observing the loading of an aircraft: this makes better sense to me, since, when expressing the loading of an aircraft, it would be easier to say that the aircraft is now being loaded "this many times its weight", compared to this many newtons; this however, contradicts the definitions above.

And now to the force and moment balance analysis issue, I noticed that all components of an aircraft are expressed in terms of its load factor, which is fine, but then in performing the balance, the weight of the components are not considered. How can you ignore the weight force which is always acting on the aircraft when the load factor (per definition) excludes it? An added confusion is in that lift is considered in the moment balance, with all component's loading expressed in terms of load factor; how can you include lift, when it is already incorporated into the load factor of the components; this implies that the part is further loaded above its current loading.

I would appreciate if someone can straighten up what the load factor means, and how should it be applied in force and moment balance calculations.


texts: Which hand do fighter pilots use for the control stick?

texts:
Here is a question that has been bothering me for a while. Do right-handed fighter pilots use their right hand to hold the control stick? And do left-handed fighter pilots use their left hand?

Or is it the other way around? Or do they maybe use both hands a lot of the time? It also brings up the question as to what the other hand is expected to do and which side of the cockpit the most common control buttons are on.

My guess is that since most people are right handed, they use their right hand. There's also triggers on the yoke so it seems all the more likely that the right hand is used for right-handers.

I'm asking because you look at video games and their controllers. They always use the left joystick for moving the character. In the case of flight simulators, the left joystick is used as the 'stick' or yoke. So you're pretty much left with no choice but to use your left thumb. Not saying this is awkward for video games, however, on those big joysticks for PC games, I remember I always used my right hand.

Also, let's ignore civil commercial piloting because those seem to usually use steering wheel type controls, not a traditional stick. Please let me know if you're a fighter pilot when you answer, because the triggers on the yoke have an effect on which hand you're most comfortable with.


texts: Does counter-rotating propellers on multi engine airplanes have critical engine?

texts:
I read from most of the article and books that counter-rotating propellers multi engine airplanes do not have critical engine, but it just happened to my friend who did his Commercial Multi Engine Rating check-ride that he answered there is no critical engine on counter-rotating propellers and the examiners failed him.
And one of the instructor said that he should answered both engines are equally critical.
 is there any terms that stated that counter-rotating  propellers has both engione critical?


texts: What is the motivation behind designing a control stick that does not move?

texts:
According to Wikipedia (and various other online sources), the control stick on the F-16 does not move. The input values are determined by the amount of force acting on the stick, rather than the deflection angle/distance away from its neutral position like the majority of sticks and yokes. After pilots reported the design as "unnatural", the stick was modified so it would move a little.

Clearly the designers must have thought that having a very stiff control stick is advantageous. Why?


texts: Why are the transition altitudes/levels different around the World?

texts:
I got tasked by my instructor pilot to find out why each country has a different transition altitudes / levels. For example in the US it's FL180 and in Saudi Arabia it's FL150.

Can someone help me with that, and if possible provide any document that talks in details about this subject.


texts: What's an "outrigger" for parking aircraft on a carrier?

texts:
In this picture of the USS Intrepid (CV-11), there appears to be an aircraft parked with the tail hanging off the deck:

(Source)

The caption gives a clue:

  The U.S. Navy aircraft carrier USS Intrepid (CV-11) operating in the Philippine Sea in November 1944. Note the Grumman F6F Hellcat fighter parked on an outrigger forward of her island.

This "outrigger" appears to be some sort of triangular structure to partially support the aircraft's weight:

Further research, however, turns up no more information about this "outrigger." So:

What exactly was this device?
How was it used?
What's its history?
Who manufactured it?


texts: What do different runway depictions mean in the Chart Supplement?

texts:
I cannot find a digital Chart Supplement (AF/D) glossary.

What is the length requirement to depict a runway as a dashed line vs. solid black?

The depiction for Melbourne, Florida shows one runway with a dashed line and another as solid.

At JFK, all the runways have dashed lines. What do the different depictions mean?


texts:
In La Réunion, people are currently searching for plane debris that could be from the MH370 crash and this morning this object was found.

Can anyone identify it?


texts: What prevents jet engine designs with larger bypass ratios?

texts:
In commercial aviation, it seems jet engines grow and bypass ratio increase with newer engines. Here is some examples:

1963: bypass ratio: 0.96 (P&W JT8D)
1970: bypass ratio: 5.0 (P&W JT9D)
1984: bypass ratio: 5.3 (P&W PW4000)
1984: bypass ratio: 6.0 (P&W PW2000)
2004: bypass ratio: 8.5 (Rolls-Royce Trent900)
2007: bypass ratio: 10.8 (Rolls-Royce Trent1000)
2015: bypass ratio: 12.0 (P&W PW1124G)

The bypass ratio has been multiplied by nearly 2 in 30 years (1970 -> 2015).
I understand the need of really high bypass ratio to decrease fuel consumption while increasing thrust. To have big bypass ratio, the high pressure part of the engine must be small compare to the overall size of the engine.

What prevent jet engine designer to design smaller high pressure part or bigger jet engines to increase the bypass ratio?
Is there someone that has made prediction about the increasing bypass ratio in the next decades and written it in a serious article?


texts: What would be the Sref i.e. Reference Wing Area for Drag Build Up Calculation in case of a box wing design?

texts:
Would Sref be sum of areas of both, the front and the back wing? or just one wing? Assuming both the wings have equal areas (image below)
Details - So, I am calculating drag using the component drag build up method and using the below equation for the following parts of my box wing design.

Front Wing
Aft Wing
Fuselage
Tail

as you can see in the equation below, Swet for all different parts are divided by "Sref". For example assuming that both wings have area of 10m^2 and therefore wetted area of roughly about 20m^2 each.
for Cd0 calculation what should use as my Sref? total lift generating area of the aircraft, as in 10+10=20? or just the area of any one wing, 10?
If I use 20, for example, and apply the below formula for the front wing, my (Swet/Sref = 1) whereas it's = 2 if I use, Sref as 10m^2?
Basically, my total CD0 values changes drastically as I change my Sref according to the below equation, why is that?


texts: What ICAO codes are reserved for TIS-B use?

texts: Using my ADS-B receiver, In the past few months I've seen a lot of what I think are TIS-B contacts.  They seem to cycle through a few different ICAO ID prefixes, but I see a lot that are of the form (in hex) 29xxxx and 31xxxx. E.g. 298c12 and 318512.  I'm looking for a specification of exactly which ranges of ICAO codes can be used for TIS-B.


texts: Is my understanding of magnetic variation and declination (for a VOR) correct?

texts:
AIXM (the XML-based exchange model for AIP by Eurocontrol and european AIS) defines the following properties for a VOR:

codeTypeNorthA code indicating the direction of the "zero bearing" provided by the station, values: "TRUE" (true north) or "MAG" (magnetic north).
valDeclinationThe angular difference between the direction of the "zero bearing" indicated by the station and the direction of the True North.
valMagVarThe local angular difference between the True North and the Magnetic North.
dateMagVarThe year the magnetic variation was measured.

Now say we have a VOR with the following values:

<codeTypeNorth>MAG</codeTypeNorth>
<valMagVar>0.27</valMagVar>
<dateMagVar>2018</dateMagVar>

Am I correct with the following statements?

valMagVar is a positive number, therefore magnetic north is east of true north.
codeTypeNorth is "MAG", therefore the VOR is aligned towards the magnetic north. Since the magnetic variation is +0.27°, the "zero bearing" is equally +0.27° east of true north and therefore the (undeclared) valDeclination must be +0.27° as well.

Please don't comment on the practical relevance of this question. I'm developing and documenting OFMX (a derivative of AIXM) we will use as our future well-defined exchange format for https://openflightmaps.org and I want to be sure to be 100% sure I explain the terms "magnetic variation" and "magnetic declination" accurately in the OFMX documentation.

Thanks a lot for your help!


texts: When did the FAA begin offering added-rating tests for flight instructors?

texts:
I don't recall there being abridged versions of the knowledge test for added CFI ratings when I earned my initial CFI certification such as AIF(flight instructor instrument added rating), and back then I would have had to have taken the full FII(flight instructor instrument initial CFI certification) test.

I could have simply forgotten since 2009.

When did the FAA begin offering added-rating flight instructor knowledge tests?


texts: What makes a bomber able to deliver nuclear bombs?

texts:
Currently the German Luftwaffe has Panavia Tornados to deliver American nuclear bombs in case of war. The bombers are getting older and are currently modernized. The German Luftwaffe also has Eurofighter Typhoons which are said to not be able to deliver nuclear weapons. Why is that so? (Same goes for the F-35 and the F-22)

AFAIK all that's needed for an aircraft to deliver nuclear bombs is

The ability to actually carry the bombs, which probably conform to some standard "form factor".
Some special electronics for arming the bombs, which must be installed into the bomber - this probably also follows some standards.

Is that all? I seem to remember some special aerobatic maneuver the aircraft should be able to perform to allow the survival of the crew. Does that exist and is it a problem for modern fighter/bomber aircraft?


texts: Will I not be able to descend with an airfoil that stalls at -0.5°?

texts:
This stats says this airfoil stalls at -0.5°,does this means if I have this airfoil as a wing ,I won't even be able to  have a descent aoa?

!


texts: Does altitude influence the flight range of an engine driven aircraft?

texts:
I'm reading a chapter about flight performance during the cruise phase and the influence of altitude.

My book (Aerodynamica, prestatieleer en vliegtuigtechniek by Bas Vrijhof on page 155, written in Dutch) describes the following:

  Naarmate de hoogte toeneemt, neemt de luchtdichheid af. De afnemende
  luchtdichtheid heeft een effect op het benodigde vermogen, en dus op
  de prestaties. Om bij een lagere luchtdichtheid te vliegen is meer
  vermogen nodig. Om bij een lagere luchtdichtheid voldoende lift te
  houden moet de TAS toenemen, dat kost vermogen.

Translated to English:

  Airdensity decreases with altitude. A decrement in airdensity influences flight performance. To fly at a lower airdensity more engine power is needed. To maintain enough lift at lower airdensity the TAS needs to increase, this comes with the cost of engine power.

This is totally clear to me. Then the book says.

  Endurance...
  Meer vermogen betekent een hogere brandstofverbruik. De endurance neemt daarom af.

Translated:

  Endurance (amount of fuel per hour), more engine power means a higher fuel consumption. The endurance decreases with an increase in engine power.

Again, this is also clear to me.

  Range...
  De range verandert niet bij toenemende hoogte. De range is niet afhankelijk van de vlieghoogte. Wel neemt de Vmax range toe als de hoogte toeneemt.

Translated:

  Range (maximum flight distance, amount of fuel per km) doesn't change with an increase in altitude. However, the Vmax range increases with an increase in altitude.

The last sentence is confusing me.
Because my instincts say that a higher fuel consumption comes with a shorter flight distance. So my question is:

Is it really true that the altitude doesn't influence the flight range? Does the book has an error?


texts: What is the name for a flap that increases the wing's area but not its camber?

texts:
Flaps are high-lift devices mounted to the rear portion of an aircraft's wing.

Some types of flaps increase lift by increasing the wing's camber, or, at least, that of its lower surface (plain flaps, split flaps, Junkers flaps).
Most flaps increase lift by increasing both the wing's area and its camber (Fowler flaps, gouge flaps, Fairey-Youngman flaps, zap flaps).

What would one call a flap that increased the wing's area, but not its camber (like the first stage of a Fowler flap)?


texts: Why does the mass penalty of cantilever vs externally braced wing decrease with aircraft size?

texts:
From Wikipedia
Cantilever wings require a much heavier spar than would otherwise be needed in cable-stayed designs. However, as the size of an aircraft increases, the additional weight penalty decreases.
Why? The article does not have a citation there.


texts: Is it possible to start the engines while on push back?

texts:
I was recently on a flight and the the engines started after push back has been initiated. I was always under the impression that the process required a GAU to feed pressurised air or use of the APU.
But the APU wouldn't be used at a major London airport when ground services are available?

How did they start then?


texts: Wheel or skid? Which advantages does each one have when used as the landing gear system compared to the other one?

texts:
I would like to discuss this topic in depth, as I have not found a clear answer yet.
Which are the advantages of using skids instead of wheels (or viceversa) for the following considerations?:

-As the nose landing gear (case: Dream Chaser)

-As the whole landing gear (case: Eurocopter HH-65 Dolphin (wheels) VS. Bell 205A-1 (skids)


texts: How does the B777 Side brace locking mechanism work?

texts:
The B767 has jury strut actuators and their working is pretty straight forward. They oppose the collapsible geometry of jury strut and lock them in the over centre locking position.

But for B777 this doesn't seem to be the case, I sure can see a small locking piston, but I quite don't understand its working, it seems different from the 767s simple strut locking mechanism

Would be great if you could provide explanation with some picture references.


texts: Why do airplanes use an axial flow jet engine instead of a more compact centrifugal jet engine?

texts: Axial flow jet engines take up a lot of space. Centrifugal jet engines create high pressure. Can you create a centrifugal air pump that pushes as much air as a axial jet engine. Centrifugal air engines reach higher speeds from my research. What are the main disadvantages of centrifugal air engines from the standard axial engines.


texts: What Caused the Engine-Failure of Southwest Airlines Flight WN-3472?

texts:
What caused the damage on Southwest Airlines Flight WN-3472?

The inlet section of the engine is missing but the fan and nose-cone are still visible.
Pictures taken during flight even seem to show the fan windmilling.


texts:
Just looked at the Lamac ( light aircraft manufacturers association of Canada) specs.  If I remember correctly, They want to see a maximum of 3 psf wing loading for Vc of 60mph, rising to a maximum of 12psf for Vc of 120mph and above.

Why only 3 psf?  Looks to me they just want standard wings with a cl max of 1.5.

The Zenith 701 stol has a wing loading of about 10 psf, yet has a Vc of about 60mph, with a cl of about 3.


texts: How much fuel does the A380 use for taxiing before takeoff?

texts: How much fuel does the A380 use for taxiing before takeoff and after landing? What does it cost at today's pricing?


texts: How do pilots avoid thunderstorms at night over the pacific en route to Australia where there is no radar? And what if a large front develops?

texts: While there is some limited radar on board for pilots, we hear that there is no radar over the ocean which is why flight locations are estimated. As the distance between the United States and Australia is lengthy, how do pilots avoid thunderstorms over the Pacific en route to Australia at night, and what did they do about them If a large front develops in their way?


texts: Is it possible to hand start modern planes?

texts: I know that older planes must be hand started but are newer GA planes even able to be hand started by spinning the prop?  If so, how do you do it safely without cutting your hands off or being pulled in by the propeller?


texts: Why does load shedding still occur in jetliners (e.g., 787) when there is so much power available?

texts:
I had a few questions about how electrical generator works on an aircraft, the 787 to be specific although I know it is similar for all aircraft.

So the 787 engines have 2 VFSG each which are rated at 250 KW each which is 1000 KW -> 1 MW which is said to power a 2000 population town. Since the power is generated using the rotation of the engine, im assuming it does not always produce 1 MW , only at peak rotations?

What on earth in the plane sucks that much energy, I know the 787 is a more electric aircraft, but still how much power does it really take? If the total power output of the plane is 1.45 MW, I'm assuming the APU Gens are able to provide 0.45 MW in total to the airplane.

If there is so much power available, why does load shedding still occur in aircraft?


texts: Is the arrival segment of an IAP in PANS-OPS the equivalent of FAA's feeder route?

texts:
In ICAO's manual 8168 ("Aircraft Operations"), the term "Feeder route" is never mentioned. Instead, it states:

  8168 Volume II, "Approach Procedures": 1.2.3. Segments of the approach procedure. An instrument approach procedure may have five separate segments. They are the arrival, initial,intermediate, final and missed approach segments.

My confusion concerns the difference between the arrival segment and a STAR. Does the arrival segment imply that it is also part of an arrival procedure, or is it just the equivalent of a feeder route, which is mentioned in FAA's TERPS?

Could someone help me clarify this?


texts:
This question may sound naive but surprisingly it puzzles me.

A wing has a centre of pressure, does it mean that lift acts on point and not on the whole chord of an airfoil?


texts: Where does Google Flights get its pricing information?

texts:
I was wondering if anyone knows how I can get flight data in mass.  Specifically, I'm looking for price, time, and airports involved.

Do you know where Google, Expedia, and the likes get their flight information from?


texts: Can someone please tell me all the units for the propeller thrust equations?

texts:
This answer is excellent:-

Is there any equation to bind velocity, thrust and power?

except that it is (in practice) unusable, since all the units are missing.

I'm guessing we use meters for length (prop diameter), and watts for power.

I'm not sure what units we use for mass (grams or kilograms?) - but either way - neither of those work (grams gives answers 10x too small, and kg gives answers 1000x too large).

I have a 10,000 watt motor
My propeller is 1.25meters diameter
At full pelt, using bathroom scales on the wall, it pushes me with 35kg force

Using 0.8 for the prop efficiency, and 0.9 for the motor efficiency, and 1.225  grams/l for normal air density, the referenced formula gives 367448 grams thrust - 10 times too much.

So yeah... what are all the units supposed to be?


texts: Has there ever been a seaplane with inflatable airbags rather than traditional pontoons?

texts:
Traditional pontoons are big and cause a lot of drag. It would be nice to retract them like normal landing gear but they are just too big.

Has there ever been a seaplane with inflatable airbags instead? They way I imagine it is a lot like normal landing gear, with lowering struts from the wings or belly. But instead of wheels, it has a wound-up airbag that's unrolled and inflated.

I think this would save a lot of drag and weight, and I'm a little surprised that this apparently doesn't exist over the 114 years or so of airplane history. Is there something unfeasible about this concept? I suppose getting propeller clearance over the water is the biggest concern, but I would think slightly long legs on the landing gear would be sufficient and well worth it to save all that weight and drag from those big pontoons.

Edit: This is for the really small planes.


texts: What is fuel consumption of an A330 during climb and descent?

texts:
I want to know how to calculate or estimate an aircraft's fuel consumption when climbing from sea level to 15,000 ft, followed by a descent to 10,000 ft.

I would like to see an example for an Airbus A330-300 with CF6-80E1A4 engines.


texts: If a glider had human pedal powered propellers how much extra distance could you go?

texts:
Imagine an amateur cyclist could generate 100 watts of power (professional ones can do 200-300), would it be possible to put that to use in a glider to fly further?

For example you pedal for 15 minutes and it is stored in a battery, and then it is used for 2 minutes of propeller power.

I guess one concern is that the addition of [pedals, battery, motor] would outweigh any potential energy gains.


texts: Do small civilian aircraft have autopilots?

texts: If not, why? Doesn't it make flying safer? It seems to me that automating a small plane should be easier than automating a car (excluding dealing with Air Traffic Control). Is it too expensive?


texts: What mode is the Boeing 777's autothrottle in right after touch down?

texts:
This question came to my mind when I saw the Emirates B773 (Dubai on Aug 3rd 2016) accident.

I saw a couple of 777 cockpit videos and I saw that autothrottle (A/T) is widely used during landing and they just turning the autothrottle knob left or right to set the speed. Question. Does anyone know what mode is the 777 in right after touch down? Especially the A/T? As far as I know the aircraft goes to roll out mode (whatever that means). Lets assume they initiated a go around right after touch down for whatever reason. The pilot assisting just turned the knob again (as usual) instead of pushing TO/GA but it was ineffective as A/T was disengaged automatically. So yes, it is guessing without any knowledge so lets focus on my question. What mode is the A/T in right after touch down?


texts: Can normal PC headsets replace 'aviation' headsets?

texts:
Aviation headsets have noise reduction and a larger jack (1/4") than most PC headset counterparts (1/8"). But there are many excellent quality PC headsets with sound-proofing materials which eliminate external noise. So can I just plug in my PC headset using an adapter? (Let's assume that I have a PC headset of equally good build quality, and comfort)
EDIT: What exactly are the functions of an aviation headset?
I've already looked at this topic, and this doesn't answer my question - I understand what aviation headsets do, but I'm asking (out of academic interest) whether they can be replaced with a superb quality headset for a PC, like for example, the Kingston HyperX Cloud II. If not, what exactly is different other than quality and noise cancellation? Again, this is for academic interest...


texts: What is the identity of this abandoned, wrecked Sudan Airways airliner?

texts:
The other day, I was browsing Twitter, when I came across this picture of an airliner posted by a Sudanese local (thought it was a Boeing 737, but a friend of mine pointed out that it was an Airbus A300). I tried Google Image Searching it, but couldn't find any more details about how it got to be wrecked in this condition ...
Could anybody shed a light on this?


texts: How much physical strength is required to control a Cessna 172?

texts: I have heard a number of folks tell me that one needs a certain amount of physical strength to be able to control the Cessna 172. Is that true? I'm flying sims now, just wanted to know.


texts: Are well-known IR AAMs 'compatible' with aircraft from other countries?

texts:
The AA-2 Atoll was a Russian reverse-engineered clone of the AIM-9B Sidewinder.  There are some sources that indicate, with varying degrees of veracity, that it was a good enough clone that the two could be used with the other side's aircraft (i.e. early MiGs launching Sidewinders and Western aircraft of that era launching Atolls).

However, the Russians have developed other short-range AAMs since then (Aphid, Archer), and the US has evolved the Sidewinder quite significantly from its humble roots as well.  In addition, other Western IR AAMs have been developed as well (such as the Israeli Python family).  This, along with the presence of mixed coalitions and even mixed air forces such as Malaysia's in this modern age, has me wondering: whose IR AAMs can be launched from whose planes?

More specifically:

Are current Russian jets (such as Flankers and Fulcrums) backwards compatible to the AA-2's electrical interface? (Bonus points if they can actually launch the AA-2 still.)
How backwards compatible are current Western jets (on external stores stations) to early Sidewinders, electrically speaking? (I know that some early Sidewinders required a cryobottle in the launch rail, we can ignore that for now.)
How forwards compatible are current Sidewinders to early Western jets? (i.e. could you launch an AIM-9M or an AIM-9X in analog mode off of an F-5 or A-4?)
Are other Western AAMs (such as the Israeli Python) compatible with the Sidewinder electrical interface?  (i.e. can a US F-16 hang a pair of Python-4 missiles off its wingtips and have them work "out of the box"?)
Last, and most of all, could you launch a modern Sidewinder (AIM-9L/M/P or AIM-9X in analog mode) from a Russian/Soviet jet (of any era, bonus points if it's one of the modern ones though), or have the interfaces diverged enough over the years to make that impossible?  Do the Malaysians need two stocks of IR-guided AAMs at all times, or could they get by on Sidewinders if they ran out of Archers or vice versa?


texts: Do aircraft use some kind of stability control to keep the aircraft on the runway during landing?

texts:
Modern automobiles use an electronic system called ESP to keep the car on track in slippery situations. Do modern jet liners have a similar system to aid the pilot in keeping the aircraft on the runway after touchdown?

Especially during crosswind landings you can feel the plane swilling violently left/right after touchdown.


texts: Do all aircraft carry depleted uranium as counterweights?

texts: I was told that most aircraft had depleted uranium on board as counterweights. I have not seen one myself. Do all current modern aircraft have depleted uranium on board?


texts: Does density altitude affect actual altitude?

texts:
Student pilot here, working on my first rating. A lot has been drilled into my head about density altitude as we approach the hot summer months here in the northern hemisphere, and how it causes the plane to act as though it were at a higher altitude—less lift, less power, less thrust—but no one seems to understand when I ask if this also puts the aircraft higher in the sky, as well.

As near as I can understand, the atmosphere actually expands and becomes taller under hot conditions, and the various pressures that we associate with certain altitudes are actually further apart. Is there a flaw in my understanding?

It mystifies me that no one I've talked to seems particularly concerned about something that could potentially throw off your ability to judge your true altitude. Wouldn't you need to be more concerned about cold-weather density altitude when crossing mountain ranges? The mountains don't get shorter just because your pressure levels are closer together . . . right?


texts: Why is the landing area of an aircraft carrier angled to port side, not starboard?

texts:
On a modern aircraft carrier, the landing area is not aligned with the axis of the ship.

Given this part of the ship needs to be asymmetric, why do most (if not all) angled flight decks point to the left side of the ship (and not the right)? Is there any advantage to favor this side?


texts: When I perform a go around, how it is guaranteed there will be no traffic on my go around route for both controlled or uncontrolled airport?


texts: As a contractor for an FBO, is it okay for us to transmit Internet signals right above the tarmac?

texts: I have been looking for the FAA Regulations on this with no luck, we are contracted IT with a local FBO and they want to provide internet to all their hangers. The easiest way would be to put a line of sight connector for the network so we can pass the internet over it, HOWEVER it will shoot over the TARMAC and I am not sure if FAA prohibits that. It is only for ground operations the Airplanes won't be using it but I just wanted to cover myself before I did it.


texts: What is the relationship between speed, torque and pitch in a helicopter?

texts:
Can someone clarify the relationship between aircraft speed, torque, prop length and pitch and how this applies to a helicopter.

In addition I want to know if the amount of lift a helicopter generates changes dependant on pitch, how much does the pitch change?


texts: What are the difference between FMC, FMS and MCDU and what do they do? +2 more questions

texts:
What are the difference between FMC, FMS and MCDU and what do they do?

Do airliners have all of them or just 1 or 2 of them?

Do pilots learn how to program them/it?

FMC = Flight Management Computer

FMS = Flight Management System

MCDU = Multi-Function Control and Display Unit


texts: How much time does an landing/take-off add to an otherwise direct flight?

texts:
I'm interested to know how much time a descent and ascent to crusing altitude takes as part of a longer journey.

A standard jet-aircraft (for example a A340 or 777) flys for eight hours from City A to City C. While doing so it flies over City B.

Now the same jet flys from City A to City C but as it approaches City B it descends and lands at B. The plane taxis to the gate. As soon as it's there it pushes back, requests take off and returns to the cruise flying to City C.

Approximately how much time is added to the journey by virtue of having descended, landed, taken-off and ascended to cruise ? Assume no ATC delays etc.


texts: Do pressure altimeters take into account differences in temperature?

texts:
I work as ATC in Korea and recently, I have some question about winter altimeter setting.

In my facility, we use winter altimeter adjustment because the aircraft's pressure altitude is lower than true altitude in winter. I know this is due to air density difference in winter and summer.

My question is, can the altimeter setting (inch or QNH) include this adjustment? I know that the altimeter setting which ATC gives to the pilot changes every time according to the ground QNH condition. If the altimeter setting can include the adjustments, it would be convenient to ATC and pilot.


texts: What exactly does the MB-326's 'relight' button do?

texts:
The following picture shows the engine throttle of an Aermacchi MB-326, which is powered by the Rolls-Royce Viper turbojet:

(source - all photos © Drive&Fly Model Club)

I wonder what exactly the RELIGHT push-button is for. It's clearly not the 'reheat' control (another word for afterburner, which is not fitted on the Viper, apart from some amateur variants...)

I would guess it controls the engine ignition for use in case of flame-out, but then I noticed this other photo, showing what appears to be the starter/ignition controls (located in front of the throttle):

so my question is: what exactly does the relight button do, as opposed to the starter/ignition controls?


texts: How to derive the Vortex line segment parallel to a plane using the Biot-Savart law?

texts:
I am trying to understand what is shown in this book (Applied hydro and aeromechanics), page 187

The velocity induced at a given point on a parallel plane by a vortex segment of length $b$, and strength $\Gamma$ is shown to be,

$v_1 = \frac{\Gamma b \, sin \, \alpha}{4 \pi R^2}$

Can anyone please show the steps on arriving this formula by applying Biot-Savart law ?


texts: Wingtip landing light lenses are hazed - what can I do to make them clear again?

texts: I have wingtip landing/taxi lights on my plane.  They have acrylic covers to protect the bulbs.  They have started to haze over time, similar to the effect of car headlights.  I am wondering if anyone has experienced this and can provide information on how to correct this issue.  I feel as if this might be affecting the ability of the bulbs to direct light on the runway/taxiway efficiently.  I am starting to eye some of the cleaners that say they can correct this in the automotive aisle, however I am very hesitant.  I don't want to buy new covers, as I am sure there is a better/cheaper option.


texts: Do software simulations and wind-tunnel tests accurately predict Cd and Cl in real-world conditions?

texts: Will the lift coefficient (Cl) and drag coefficient (Cd) I obtain by using software simulations or subsonic wind-tunnel tests be the same as on an actual aircraft while cruising? Or will there be some error?


texts: Why are so many ATR involved in accidents in the past years`?

texts:
I asked myself a question why are so many ATR involved in accidents in the past years?

ATR-72, 16 October 2013, Lao Airlines Flight 301
ATR-42, 19 October 2013, P2-PXY, Air Niugini
ATR-72, 23 July 2014, TransAsia Airways Flight 222
ATR-72, 02 February 2015, TransAsia Airways Flight 235
ATR-42, 16 August 2015, Trigana Air Service Flight 257


texts: Why does an elevator deflection (step) result in a nonzero short-term-steady-state response in pitch rate?

texts:
I know from the simplified Short Period linearized equations (state space with Angle of Attack ($\alpha$) and Pitch Rate ($q$) as states) that the steady-state value of the pitch rate response to elevator deflection (step) is non-zero

I can also relate that to the spring-mass system and understand that the concise derivatives $M_{alpha}$ and $M_q$ work as spring and a damper, respectively.

I think (would appreciate confirmation) that the term short-term steady state should mean that the phugoid motion is going to take over eventually, being the dominant mode.

However, I would like to understand that physically, because $\alpha$ and $q$ seem to be both on steady state (impossible unless flight path changes). Also, I would expect $q$ to return to zero at some point. Does it mean this equation is oversimplified in this regard?


texts: Why are commercial propeller aircraft smaller than commercial jet aircraft?

texts:
I've read that turbo-prop aircraft are more efficient than jet-aircraft. Browsing this Wikipedia page it looks like in general, jet airliners burn less fuel per passenger. I imagine this is due to jet aircraft typically carrying more people, and flying longer in cruise. Is there some fundamental reason why traditional propeller designs couldn't be scaled up to 150+ passengers and trans-oceanic ranges? If it was possible, would air travel become substantially more efficient per passenger?

Edit: Perhaps a better phrased question would be: are turboprop aircraft always more efficient, regardless of airframe size? Or is there some regime where modern turbofans take over? I'm specifically asking about fuel efficiency (i.e. ignoring noise / speed).


texts: Why do holds at or below 14,000 feet have different procedures?

texts:
When holding at or below 14,000 feet, the time for each leg is 1 minute. However, above that altitude, the legs are flown for 2 minutes, and the turns for 1 minute and half.
Are these differences due to airspeed, or any other recommendation?


texts: Does autopilot disconnect when a danger alarm like GPWS triggers?

texts:
I was wondering if any of the (E)GPWS callouts would make the autopilot disconnect?
If the Alpha Protection is active (like in Bilbao, 2014) would it disconnect? That would give PF full control of the aircraft and could help to recover from the upset, correct?


texts: Why don't cockpit windows suffer pressure leaks?

texts: The de Havilland Comet had pressure leaks inside the square windows which resulted in 3 incidents of the aircraft breaking apart in mid-air. A cockpit window has a similar square window and should be susceptible to pressure leaks.Source:(prosim-ar.com) Here is a Boeing 737 cockpit outer view. As you can see the windows are square which makes them susceptible to pressure leaks because of their square shape like the de Havilland Comet. So why doesn't the Boeing 737 cockpit windows suffer pressure leaks? And what modern methods do engineers use to reduce pressure leaks and why aren't square windows used on airliners any more?


texts: Why do airlines in the United States of America use total time as an eligibility requirement for employment?

texts:
Airlines in the United States of America have varying total time requirements to determine eligibility for the potential employment of applicants. Why do airlines set total time requirements beyond the minimums that are present to achieve the required ratings?

I realize that this question is prone to answers that are purely speculative or opinion based, so I caution against posting such an answer. I am asking for concrete reasons. For example, airline executives may have given answers in the form of interviews. I also speculate that airlines may have insurance requirements or institute total time requirements to control the number of applications they get.


texts: When is International Procedures Training required?

texts:
The companies that I have worked for in the past require International Procedures Training like the ones offered by Scott IPC, Flight Safety, CAE Simuflite, etc.

Under what conditions is this training required?  (I.e. do I need it to fly to Canada, Mexico, or the Bahamas or is it just to cross the Atlantic/Pacific?)

What regulation requires this training and how often is it required?


texts: Do twin engine airplanes have increased roll stability?

texts:
Do twin engine airplanes with counter rotating props have increased roll stability?
Imagine a gust of wind hitting the airplane from the front right quarter.
The gust hitting the front of the plane first would yaw the plane to the left, before the rear vertical stabilizer can counter the yaw, the airplane will then roll to the left as the right wing sees more lift.
With a twin engined aircraft, the left engine would counter that yaw.
If less yaw, would that mean less roll, and therefore more roll stability?
Is this correct thinking?
If not, what can be done to increase roll stability besides using a maximum dihedral of about 6 deg and the addition of ventral fins, and wing sweep?


texts:
When I was a young student pilot, long before the FAA prohibition on polished frost went into effect, an instructor left a six-inch square of frost on the wing to demonstrate how fast it would disappear after takeoff.  Sure enough, we hadn't even reached pattern altitude and the frost was completely gone.  Furthermore, in my experience frost never forms on an airplane as long as it's moving, or as long as there's sufficient airflow moving across it.

I've never been able to find a satisfactory explanation for this.  Why doesn't frost form on a moving airplane?


texts: Can a FAA "Letter of Authorization" be used when there are no pilots that are current on a type rating?

texts:
A pilot has multiple type ratings and wants to train for another aircraft (e.g. DC-4) which is on his Part 125 certificate. Unfortunately, there are no available pilots with currency on this aircraft type, but some do have the rating.

Can the FAA authorize a "Letter of Authorization" for the pilot to train based on his other type ratings? Or, could the FAA issue a letter of authorization to a pilot with the appropriate type rating to be used as a training instructor?

As of today the FAA has a few examiners who can issue the type rating for this aircraft, but have lapsed the currency requirement. Therefore, the question is one of training and how to obtain it; not the actual addition of the rating which they can provide.


texts: How can a computer model yield two possible flight paths of MH370 in South Indian Ocean?

texts:
I am reading this article on the NY Times, where they show two possible flight paths of the missing flight MH370 in the South Indian Ocean:

I am wondering how they can come up with such specific paths, when the only information we have are those two arcs (those arcs are not paths, rather the last satellite ping happened somewhere on the arc).

How can anybody create a computer model with just this information? Or does it mean that the modelers have more information available than the general public?


texts: How are aviation sectionals and enroute charts created?

texts: Who exactly handles this?  Is this done by the US Government via one of its printing offices?  Or is this private?  I know Jeppesen does some charts, especially approach plates, but I am not totally sure how all this is done.


texts: Operating a floatplane/seaplane on water through a drawspan?

texts:
Lets say that you were in a floatplane (whether it be Terry's floating Cub or a big ol' Martin Mars) and the only otherwise-reasonably-suitable landing spot in the waterway where you are trying to go, or the taxi route from your landing site to your destination dock for that matter, is crossed by a movable bridge (aka drawbridge) that will not clear your aircraft when the drawspan is closed.  How would you, the floatplane pilot, signal the bridgekeeper to open the bridge so you can land/taxi through the navigable channel provided, especially considering you don't have a foghorn to signal the keeper with, and the keeper only has a marine VHF radio, which you may not have?

Assume that the drawspan can clear your plane when open (always true for bascule and swing spans; landing under a liftspan would be rather challenging though), and that the bridge is operated by a local bridgetender 24/7 (lesser-used drawspans often require prior notice, and there are also remote-control drawbridges out there that use sensors and/or CCTV to indicate the presence of marine traffic to a bridge operator sitting far away).


texts: For find a value of obstacles height below mentioned in intermediate segment why I should take the IAF MOCA instead of FAF MOCA?

texts: It is said that we have to think all risk of flight in this segment that's why we have to take the 4420ft because the plane can be situated any point in this interval


texts: Can ailerons be used for pitch change in the event of elevator failure?

texts:
On standard fixed-wing aircraft that have both ailerons and elevators, can ailerons function as elevators for pitching movement if the elevators fail? Technically it should be possible if both ailerons can rotate in the same direction simultaneously.

If so, what are the key differences and problems if the center of gravity of the aircraft was forward of the ailerons or behind the ailerons?

To my understanding, the farther back the control surface (which causes the pitching) is to the center of gravity, the bigger the pitching moment which results in a more stable configuration.


texts:
An airplane has an engine that pushes its flight. What force pushes a glider to fly?  Is it gravity? I think the flight of a glider is driven by gravity, but some people disagree with me. They say gravity acts vertical, it has no component in the horizontal direction. Am I wrong?

Please note that this question is not specifically asking about what (thrust-like) force acts opposite to the drag vector.  The direction of a glider's flight path as viewed from the earth may not necessarily be opposite to the direction of the drag vector-- for example, the glider may be travelling horizontally over the ground at constant altitude, or may be rising straight up in ridge lift or wave lift-- and this question may be construed as asking what force is pushing the glider along the direction of the flight path as viewed from the surface of the earth.


texts: Does a sudden drop of the velocity of the headwind affect the airspeed by lowering it?

texts:
I had a discussion about air speeds with one of my instructors recently. He is claiming that there is a sudden drop in the wind velocity as you get closer to the ground (which is absolutely true, due to the wind friction with the ground). However, he also says that this will affect the airspeed by making it lower and this could be dangerous because it could lead to stall conditions.

For example: he says that, if my approach is with 90km/h airspeed, the headwind is 30km/h at a certain height and by the ground the headwind goes down to 10km/h, and the stall speed is 80 km/h, I will stall because the air speed will drop down to 70km/h.

Here is where I am confused, since I have read before that the wind does not affect the air speed in any way and it will only affect the ground speed by making it 20km/h higher.

Could you please try to make this clear for me?


texts: How to calculate your landing ground roll distance with this chart?

texts:
Under these conditions:  Pressure altitude  5,000 ft, Headwind  Calm, Temperature   101 F
I have no idea how to even start


texts:
Question

Would a golf ball ingested into an engine, or impacting a windshield cause meaningful damage to a commercial airplane?

The scenario below outlines that this is possible, but the principle question is: would it actually matter, as in, would it cause the same level of damage as, say, a strike from a single bird?

Plausible Scenario

At McCarran airport in Las Vegas (KLAS), runway 1R is situated just across the street from a driving range. Several years ago, I was hitting balls on this range when a 747 landed on 1R. It seemed impossibly low; many people on the range stopped hitting to point and take pictures. For context, here's a video (not mine) taken from nearly the exact same spot, with an approach to the same runway.

At the time, I remember thinking "That plane is very low... what if it got hit?" Appearances are often deceiving, so my initial assumption was that it must be higher than I thought, so a did a bit of basic trig to find out:

The touchdown markers on 1R are about 4,250 feet (red line in picture below) from the top-level hitting stations. With a 3 deg. glide slope, the plane would have been roughly 225 feet above the ground when passing over the driving range (slightly lower down range when balls that have been hit are at their highest point).

(Image: Google Earth; own drawing)

With a 21-degree 7-wood which I hit about 200 yards, the ball would reach an apex of around 230 feet.

So, wind, timing, and the quality of golf shot actually struck notwithstanding, it seems at least possible that a ball hit from off that range could hit an airplane. In other words, the "bounding box" of the plane at least theoretically intersects a line representing the maximum height of a shot from the driving range. Thus, it seems unsafe, even if the chance is 1:1,000,000 (or greater).

I have to assume that since KLAS is one of the busiest airports in the U.S., that this is not actually an issue, otherwise changes would already have been made.

However, if an impact or ingestion were to occur, are there circumstances where it would be a "significant" event?

Notes

No one, esp. myself, was trying to hit the plane.
Despite #1, there are at least 50 hitting stations, which means lots of shots in the air as the plane is passing over the range.
This is Vegas, and alcohol is served at that range. People do try, sometimes, to hit the guy in the little range car. I doubt that would ever carry over to a plane, but it can't be logically ruled out.
My concern is that even without anyone trying, a ball could still impact the plane. But would it matter?


texts: What features are cursor controlled on the A380 Navigation Display?

texts:
I read that on the A380 and A350, certain features on the Navigation Display can be controlled via the Keyboard and Cursor Control Unit (KCCU). However, I did not find a full list of these features. I only found the On-Board Airport Navigation System (OANS) and Brake to Vacate (BTV) as examples.

Does it include, for example, selecting elements (waypoints, navaids) for the flightplan with the cursor?


texts: Does a conversion for wheel to floats require an STC or Form 337?

texts: When you add floats to a tricycle gear (e.g. Beaver) do you need an STC to install the TSO'd floats? Or can this installation be approved with a Form 337 for a single aircraft?


texts: How to represent graphically airways and routes?

texts:
I need to write a piece of software in order to display on a map flight routes and airways. I would therefore like to know if there is a standard way of displaying this kind of information (in particular the kind of icons used for displaying waypoints, departure and arrival airports and so forth).

For example, by Googling a bit I have the chart shown below:

Could someone point me to any additional sources of information that I could use.

I am particularly interested in the icons/shapes to use as well as the kind of relevant information to show. The idea would be that the map is recognizable at once by a professional pilot and provides him all the relevant information.


texts: Why is ground effect greater over smooth hard surfaces?

texts:
Helicopter Flying Handbook: Ground effect is the increased efficiency of the rotor system caused
  by interference of the airflow when near the ground. The air pressure
  or density is increased, which acts to decrease the downward velocity
  of air. Ground effect permits relative wind to be more horizontal,
  lift vector to be more vertical, and induced drag to be reduced. These
  conditions allow the rotor system to be more efficient. Maximum ground
  effect is achieved when hovering over smooth hard surfaces. When
  hovering over surfaces as tall grass, trees, brushes, rough terrain,
  and water, maximum ground effect is reduced. Rotor efficiency is
  increased by ground effect to a height of about one rotor diameter
  (measured from the ground to the rotor disk) for most helicopters.
  Since the induced flow vertices are decreased, the AOA is increased,
  which requires a reduced blade pitch angle and a reduction in induced
  drag. This reduces the power required to hover IGE

I understand ground effect and In Ground Effect versus Out of Ground Effect. Air pressure is increased below the helicopter, reducing induced flow, increasing AOA and decreasing drag.

But why is ground effect greater over smooth hard surfaces than over tall grass, trees, bushes, rough terrain, and water?

I've searched Aviation Stack Exchange, textbooks, and the front page of Google, but haven't found an explanation.

At first I would think friction from surfaces like tall grass would hold air below the helicopter, increasing ground effect. But we know this isn't true, since this would mean there's less ground effect over a runway.

Another guess would be the terrain disrupts the air from bouncing back toward the helicopter. Does the air reflect sideways instead, meaning the force of air bouncing back toward the helicopter is what increases lift? The Helicopter Flying Handbook contradicts this explanation with the following as the core source of ground effect:

  "The air pressure or density is increased"

Don't be afraid to include complicated aerodynamics if necessary. :)


texts: How does 220 kN of engine thrust create the 700 kN required to maintain the altitude of an A320?

texts:
On the Airbus A320, the two engines produce about 220 kN in cruise, whose weight is about 700 kN (about 70 tons). The lift / drag ratio in cruise is about 15 (likely higher), meaning in cruise lift = 700 kN and drag = 47 kN (or less).

What is the accurate explanation of the figures above? How does 220 kN of thrust create the 700 kN required to maintain altitude and the 47 kN required to maintain speed?


texts: What is the physical experience of passengers in the cabin during an Emergency Descent?

texts:
I am not a pilot so please forgive any misuse of aviation terminology; I'm merely a person who is working hard to overcome a sudden and intense fear of flying.

While working through a course to overcome this issue, the topic of emergency descents came up. I learned the purpose of these and the actions the captain / copilot must take, but the experience of the passengers was not discussed.

If a commercial jet is at 40,000 feet and experiences rapid depressurization, and the captain decides to make an emergency descent to 10,000 feet, what does this feel like for the passengers? Is it like being on a rollercoaster with a 30,000-foot drop instead of the typical 100-foot? In other words, do passengers experience freefall / weightlessness?

Do unbuckled passengers go flying all over the cabin? Is all unfastened material thrown across the cabin? What happens to crew who cannot make it to a seat fast enough? How common are these rapid descents in commercial flying?

I imagine this is probably the most terrifying experience a person can have, if it's anything like plummeting like a meteor.


texts: Why do most authors use wingtips vortices as reason for 3D flow around wing?

texts:
Quote John Anderson Fundamentals of Aerodynamics:

The three-dimensional ﬂow induced by the wing-tip vortices shown in
Figures 5.4 and 5.5 simply alters the pressure distribution on the
ﬁnite wingin such a fashion that a net pressure imbalance exists in
the direction of V∞ (i.e., drag is created). In this sense, induced
drag is a type of “pressure drag.

figure 5.5

I agree that induced drag is just one type of pressure drag but wingtip vortices don't cause 3D flow at wing (downwash behind wing  + two rollup vortex...)
Am I right?


texts: How does a pilots license of cluster ballooning differ from other ballooning or unpowered flight?

texts:
John Ninomiya discusses his experience with developing this new style of ballooning on his Cluster Ballooning website.

Many of the site's links are now broken, but on there he formerly attested that he was granted a pilots' license by the FAA for this style of flight.

I remember the wording clearly suggesting that this license was different than other flight license. Does anyone know how it did, or could have, differed?

Any other relevant history about cluster ballooning is also appreciated.


texts: Is the Fortran language still being used in aviation?

texts:
I am an aeronautical engineering student at Istanbul Technical University and our course plan includes Fortran as a programming language. I have some doubts about that because Fortran is an old language.

Is Fortran still being used in aviation?


texts: Limits on piston-engine power for a given airframe?

texts:
I'm looking for an authorative textual source (and indeed any guidance would be useful) on the relationship bewteen a given airframe and the maximum power that it can realistically harness/cope with from a piston powerplant.

For example; if looking at something like a warbird, is there a theoretical way to work out the engine power beyond which the basic airframe design would be unable to cope with the excess torque/force/weight or is it more of an art than a science?

Thank you!


texts: What is my BHP if I open full throttle and how is it controlled?

texts: In my Cessna 152 POH it is written that the horsepower rating is 110BHP at 2550RPM. My question is: is it 100% of the power of my engine or, as someone told me, if I open full throttle I will get 75% BHP? If so, then why don't I get 100% BHP at 2550 RPM? And is there any relationship between the mixture setting and BHP?


texts: What should I do with fuel drained from the sumps during preflighting?

texts: What should one do when done sumping a small amount of fuel during a pre-flight?  Should it be dumped on the ramp? Or is it considered necessary to find the container far away from the airplane? Is it considered safe to dump it right back into the plane if it is uncontaminated?


texts: What is an obstacle identification surface and why would a pilot intentionally penetrate it during an ILS approach?

texts:
What is an obstacle identification surface?

Why would a pilot intentionally penetrate it during an ILS approach?


texts: Why is the A320 pre pressurised before take-off?

texts: I know this question has been asked, but I still haven't understood the answer. In the A320 the cabin gets pre pressurised before takeoff as we apply takeoff thrust. What I don't understand is what is the exact reason behind this. A little technical answer will be much appreciated.


texts: How do pilots hold the runway centerline during takeoff?

texts: Holding the taxiway centerline during taxi is usually done with the nose gear tiller in commercial aircraft. During take-off, until which speed is the tiller used before using pedals to control runway centerline alignment?


texts: What happens when an aircraft type is grounded while in flight?

texts:
Over the past few days, many countries have decided to ground the 737 MAX. Among these, several have also decided to deny passage to the affected models through that country's airspace. How does this affect flights which were already in the air at the time of the announcement, typically? I can see several options:

The flight returns to its origin, fuel permitting
The flight lands at the closest viable airport in the destination country if fuel is insufficient for a return to origin (minimizing the amount of time in the destination country's airspace)
The flight proceeds to its destination airport as filed, even if this means spending several more hours in the destination country's airspace than the second option
The flight proceeds to the closest viable airport regardless of whether that airport is in some third country being overflown (although I can foresee this causing immigration/visa/customs issues for the passengers)

I'm assuming that (1) is commonly used, given the flight paths on internet flight trackers yesterday, but which of the other options are rooted in reality?


texts: How do I know if an arrival procedure (STAR) clearance includes altitudes?

texts:
Air traffic control (ATC) can issue a standard terminal arrival route (STAR) to aircraft entering the terminal environment. The STAR usually communicates a predefined route of flight (fix1, fix2, fix3, etc.). The STAR procedure usually includes altitudes too.
What will I hear from a controller when I am to follow the vertical guidance on the STAR vs. waiting for assigned altitudes?


texts: Why weren't the rotor tips of the Djinn directly fed from the turbine's exhaust?

texts:
The Sud-Ouest Djinn seems to be pretty much the only tip-jet helicopter to have any sort of commercial success. It used a turbine to drive a compressor, which itself fed slightly warm air to pipes in the propeller blades, which itself exited at the tips, making the propeller turn.

This patent from the 90's says that warm air would be more efficient, as exhaust efficiency is limited by the speed of sound, and hot air has a higher speed of sound. As such, the patent is about putting a heat exchanger between the turbine exhaust and the air compressor exhaust.

But then, why didn't they simply plug both exhausts together to go drive the tips, similarly to a high-bypass turbofan? Why simply evacuate the turbine exhaust instead?


texts: Can any aircraft take off using auto-pilot?

texts:
So there are some types of aircraft that can land under auto-pilot (or is that a trope?). Can those same planes go from stop (at the gate) to in-the-air flight without a pilot actually touching a control column/flight-stick?

Caveats: I'm not talking about UAV's. Also, I'm not concerned about "would you," but rather "could you."


texts: Why do you have to keep your seat belt fastened after landing?

texts:
What's the point of the usual "please keep your seat belt fastened until the aircraft stops completely (at the gate)" in large passenger aircrafts? Since the plane is on the ground, it is not moving very quick. Even if it stopped abruptly, the seat belt won't prevent me from banging my head against the seat in front of me since it's a two-point seat belt.

The only reason I can think of is if two aircraft collided with each other, which could potentially generate enough force for the seat belt to be useful. Though, I could argue that when a plane is taxiing to the gate, it has to abide to a certain speed limit, which would render any kind of collision not serious enough to be prevented by two-point seat belts.


texts: What are the major hazards in operating a PT6 Turbine Engine?

texts:
I am just in the process of doing a bit of study in the hope of doing my Basic Gas Turbine Endorsement in the next few months, and just wanted some feedback/comments/discussion on the major hazards associated with starting, managing and shutting down a PT6 Turbine Engine (PT6 as it is the most common used Turbine Engine on an aircraft I will touch for this endorsement).

Mainly, what I am looking at is during the start - If the EGT raises above the evil 700* mark, what is the best course of action to prevent "melting the turbine"?

During Climb/Cruise Operation - What are the most common failures, and their indications?

Maintenance/Shutdown - What are the most common methods of recording Cycles? By landing or by Start/Shutdowns?


texts: What medical history questions are asked for a UK Class 1 Medical?

texts: For anyone who has been through a Class 1 medical in the UK, when they run through your medical history what sort of questions are they asking?


texts: Can I get a first class medical with eyesight of -4.25/-1.00 diopters?

texts: I'm wondering if I'm able to obtain the FAA 1st class medical certificate with the power of -4.25 and -1 in my eyes. I heard that the difference between the two eyes must not exceed 2 diopters.


texts: Has mod percent changed for Mark-1 glide slopes?

texts: Mark-1F glide slopes operate at 80 percent modulation. What was it for earlier versions i. e. Mark-1C, Mark-1D, etc.


texts: what is the physical explanation for additive drag?

texts:
from what i understand, additive drag is not really drag. it is a way to account for the variation of inlet condition due to conservation of mass.
 but i still don't get why it create drag(negative thrust) when bookkeeping the thrust value of all parts of jet engine/ducted fan

can anyone explain this for me