texts: How to calculate the vertical profile for a LOC only approach?

texts:
I am kind of stuck for calculating a descent path on the ILS RWY 7 approach into KORL. Assuming the glide slope is not available and you have to use the localizer only, what is the best way to calculate the descent and Decision to Land Point?

As you can see in the approach chart, the MDA is 660 feet for the localizer only approach. Assuming a glide path of 3°, I calculated a descent of 318 feet per Nautical Mile. However, that would not correlate to the 1919 feet at the Outer Marker.

What would be the best way to calculate / plan the approach in this example?


texts: Can regular emergency exits not work after crashlanding?

texts:
Live accounts of survivors of Bangla Air 211 mention getting out after breaking windows but not out of the emergency exits.

My question is can regular airline exits not work in such cases?


texts: Are all EGPWS-equipped aircraft using the same underlying system?

texts:
All modern transport-category aircraft and many other aircraft are equipped with enhanced ground proximity warning system (EGPWS). When this EGPWS acronym is used, is it always referring to the same system which has been integrated into the aircraft? Or is it a general term which refers to a system of various manufacturers?

To take it a step further, is there only a single system which allows aircraft to comply with the requirements to have this system integrated?


texts: How does the reusable holdback bar work?

texts:
Sources: wikimedia.org and ar15.com

Holdback bars are used to hold a carrier plane at full thrust until the catapult pulls it for launch.

Older bars (right) use a disposable shearable block (item 5) between the bar and the plane.

How does the reusable holdback bar (left) work?


texts: What is the difference between a forward slip and a side slip?

texts:
I am having a hard time understanding what differentiates the two types of slip. I understand that in a forward slip, the longitudinal axis is tilted with respect to the flight path, whereas in a side slip it is not. In a forward slip your track stays the same, whereas in a side slip it would (in the absence of wind) cause you to track toward the down wing.

My difficulty comes from the fact that the control inputs needed to enter both are the same: banking with opposite rudder.

Why then is the heading of the aircraft with respect to the flight path different, if the control inputs are the same? Is it just a question of degree, which is to say, the forward slip just requires more rudder?


texts: What is the visual manoeuvring area (circling approach) radius for PANS-Ops (ICAO)?

texts:
I'm very confused of the actual radius of the "protected area" in a circling approach for a PAN-OPS approach plate. The ICAO doc 8168 contains information for circling approach at 1 000 ft. But what about airports that are sea level? How do you calculate the radius?

P.s. Not TERPS :)


texts: What are these painted lines on the fan blades of Rolls Royce Pearl 15?

texts:
I'm not sure that they are painted lines but it looks they are. What are they for?

More images:


texts: Is it possible for an SU-25 to fly high enough to shoot down a Boeing 777?

texts: A common theory from pro-Russian netizens surrounding the MH-17 tragedy is that it was a Ukrainian SU-25 ground attack fighter plane which shot down the civilian airliner. However, MH-17 was flying at 10,500m when the service ceiling of an SU-25 is 7,000m. They say that this discrepancy is made by the fact that the Ukrainian pilot used afterburners to get to the height MH-17 was flying at. Is this actually technically possible?


texts: What is the practical usefulness of a small home made wind tunnel?

texts:
Is a small wind tunnel, like in the video, of any value for building planes able to carry a man?

Can the lift and drag, corresponding to a scaled down wing (or segment of a wing) introduced in such a tunnel, be scaled up to obtain the lift and drag of the full size wing?

See this video


texts: Is it possible for a person to fly with mechanical wings attached to his torso?

texts:
I’ve seen several adaptations of this concept in fiction from the tales of Icarus to Falcon in the MCU. But is it possible in reality for an average human to be able to fly through the air by wearing these gadgets?

If it is possible, then how would this work?


texts: Does this formula hold true for a source sheet covering a closed body of arbitrary shape?

texts:
Let me explain the picture above: We have a uniform flow and a source sheet cover the the surface of an arbitrary closed body. Let s be the distance measured along the source sheet, λ=λ(s) is the source strength per unit length along s. Assume that we already have the λ=λ(s) along the source sheet that when we superimpose the uniform flow with this source sheet, we obtain the streamline over surface of the body. Could we have this formula:
$$\oint_{body} \lambda(s).ds = 0$$  ?? If yes, is there any way of thinking to pop out this formula right away before using math to prove it? An idea is that: "the body itself couldn't be adding or absorbing mass from the flow" but I can't relate this state with the formula above.


texts: Is the Meredith effect utilized in the cowling design of air-cooled engines?

texts: The P-51 is famous for its advanced-for-its-time aerodynamics, the prime example of which is the radiator design under the belly which utilizes the Meredith effect to, in effect, turn it into a mini jet engine. Now, the cylinder walls and cooling fins of air-cooled radials are much hotter than whatever cooling liquid that's used in the P-51's water cooler, so is it possible to produce a similar cowling for the air-cooled radials? Is there any example of such a cowling on WWII airplanes?


texts:
Interesting to see how resultant force point backward from 0-10 AoA and point forward from 10-40 AoA in respect to vertical of chord line.

I find picture(below) very rare in aero-books,if someone have more this pictures,please can you upload?
(Doesnt metter which type of airfoil is..)


texts: Can BOTH instrument rated pilot under the hood and safety pilot log PIC time in IFR flight?

texts:
This question is somehow related to question: Can a non-instrument rated safety pilot log PIC during an IFR flight? , but the scenario is different.

Scenario

Pilot A and Pilot B are BOTH instrument rated. Pilot A wants to fly under the hood to practice and Pilot B will be the safety pilot. They will be flying in an IFR flight, in VMC conditions.

Question

Can both pilots log PIC time? Pilot A would be logging PIC time for being the sole manipulator of the controls, and Pilot B would only log PIC as a required crewmember/safety pilot when Pilot A was under the hood.


texts: Is there still a minimum height required for becoming a Lufthansa pilot?

texts: basically what the title says. Do I still need to be at least 165 cm to become a pilot or has this changed? There is no limit stated at their website but they also don't tell you that there is no limit.


texts: What does the snowflake with temperature symbol on an approach plate mean?

texts: I've only seen the snowflake symbol with temperature listed on this one approach plate for KASE airport in Aspen, CO. I looked for it in the legend but didn't find it. Does anyone know what the snowflake symbol with temperature means?


texts:
If I'm reading this post right: What is the effect of airfoil thickness on aerodynamic lift?

Airfoil thickness increases the lift coefficient.

And from here: What are the effects of the Boeing 787's very flexible wings?

Wing flex reduces wave drag.

I'm wondering about the how. My theory is that the air sees a thicker airfoil in a flexed wing, without actually building one. Is that assumption correct? Or is it related to the end-plate effect?

Front view of a flexed wing. Orange indicates that perceived increase in airfoil thickness.


texts: Airplane longitudinal control: pitch or power?

texts:
I recently came across some slides from a flight school teaching, for the initial climb after take-off and for the approach, the strategy of controlling/adjusting

  RoC/RoD with power

  Speed with attitude

I tried to inform myself a bit on the subject, because I am more familiar with the idea of controlling

  RoC/RoD with attitude

  Speed with power

I came to understand that this is mostly a difference between VFR vs IFR flight.
Is this true?
Does the first approach actually have benefits in terms of ability for the pilot to control the plane in VFR flight? If yes, how and which?


texts: How do turbofan engines work efficiently at cruising altitude, when the air is thinner?

texts: At FL350, for example, the air is considerably thinner than at ground level. How do jet engines efficiently provide thrust when considering fuel consumption for a certain throttle setting?


texts: CO-meter indicates 10ppm of Carbon Monoxide when I turn on Cabin heat - should I be concerned?

texts:
Our Cessna 172P is equipped with a digital CO-meter rather than the traditional Quantum eye carbon monoxide detector.
Today I was flying along in winter conditions, and naturally used cabin heat. During the flight, I heard some occasional short beeps, and couldn't figure out what it was. I looked at the CO-meter which has a red alarm light, but that light was definitely off.
On the ground, after shutting down the engine, I heard another short beep, and it definitely came from the CO-meter! The digital readout was showing 10ppm.
During post-flight, with the door open, the readout dropped to 0 ppm.
I routinely check the CO-meter battery during preflight, so I'm pretty sure the beep is not a reminder for a dead battery.

According to these sources: http://www.coheadquarters.com/ZerotoMillion1.htm , http://library.thinkquest.org/10121/textonly/exposure.htm and wikipedia 10ppm is nothing to be concerned about with exposure over a two-hour flight.

Does anyone else have a digital CO-meter and can tell if a reading of 10ppm is normal with cabin heat?
Or should I be concerned our exhaust or heat exchanger is faulty?


texts: First actual flight lesson, what to keep in mind?

texts:
With any luck, I'll soon be going into the air for my first actual flight lesson.

Short of the obvious (get a good night's sleep before; eat appropriately; try to not stress out; etc.), what should one keep in mind in anticipation of such a milestone in one's pilot training?


texts: SR-71 flew 2193 mph. How can this mathematically be Mach 3.3?

texts:
Virtually every time I read about the Lockheed SR-71 (including other threads on this forum), I see that its speed record is listed as approximately 2193 mph.  The same blurb will invariably say this is "about Mach 3.3".

But when I search for how fast Mach 1 is, the number that almost always comes up is 767 mph.

Now 767 * 3.3 comes out to 2531, well above 2193.  If I take 2193 and divide it by 767, I get Mach 2.85

I doubt I've stumbled on something new here.  So what am I missing? How can 2193 mph be Mach 3.3 when 767 mph is Mach 1?


texts: Do I have to prove my flight training time abroad when applying for a standalone FAA license?

texts:
I have done flight training in Germany and hence hold a German EASA Private Pilot License. For this I did the appropriate flight training which is documented in my logbook. But in Germany these logbook entries are not endorsed by an Instructor, it is the flight school sending the paperwork to the CAA that confirms you fulfilled all requirements.

Now I am in the situation, that I want to get a stand-alone FAA license. The two Part 61 flight schools I enquired so far both stated, that without logbook endorsement, non of the flown hours could be credited for the requirements of 61.109. But I also have German pilot friends that claim they also had no endorsements and that this was no problem while getting the license.

Is there maybe an official position paper of the FAA or something that states in more detail, what a foreign pilot needs to bring to prove being eligible?

And of course I know, that I will need additional training, but hopefully not 45 hours again. Therefore if the assumption of StephenS in the first answer is correct and I can use my logbook to prove part of the 20h DUAL (later night training is endorsed and 2.5h flying with CFIs in the US), then maybe I can reduce the requirement to about 15h. But where does the interpretation of only the 20h DUAL must be endorsed come from and not the SOLO or the rest to 40h? And what about the specific requirements in the section below in 61.109? If I have a cross country which is not endorsed, does it fulfill the requirement or not?

To keep this topic straight on this point, I am aware of all the necessities to start flight training:  Regarding medical, I have a Class 3. Regarding student license, I have a 61.75 validation of my German license with ASEL and Instrument. Regarding Visa I am already staying in the US and working legally on a visa, the flight training is just part time.


texts: What are the random, differently-coloured rectangular patches on the top of this Boeing 737's fuselage?

texts: The top section of this green-painted Boeing 737's fuselage was slightly faded and I noticed a few dark-green, rectangular patches on its top. They look like patch kits on a bicycle tyre's inner tube. What are they? My understanding is that hairline cracks/weaker spots in the fuselage can't simply be patched like this?


texts: Was "the right stuff" ever really the right stuff?

texts:
In the history of the culture of aviation, to what extent has the popular image of "the right stuff" required of a pilot ever matched the characteristics actually sought in aviation?

In this popular image, the pilot with "the right stuff" is imbued with, amongst other characteristics:

fearlessness
adventure
masculinity
a strong streak of individualism
stubborn single-mindedness
quick-thinking
sexiness
cool
self-sufficiency
a disregard for limits that bind lesser individuals
a distaste for rules
a stronger belief in himself than in authority
a strong intuitive sense of how to deal with problems in the air
... and others corresponding to the picture of the pilot who gets to walk around with a swagger because he deserves it, as vividly described in Tom Wolfe's The Right Stuff, but also represented that way through countless other descriptions and depictions in popular culture.


texts: Can light GA aircraft with FDs or couplers use the RVR reduction clause on an ILS?

texts:
If you are in a modern GA aircraft, you may have a flight director and/or autopilot that can be coupled to your ILS receiver.  (Certainly, this is true of GA glass...)

Some ILS approaches provide a clause (marked by the * on the minimums and in the notes box on the plate shown below) which allows the RVR minimums to be reduced from 2400 to 1800 if you are using a flight director, HUD, or coupled autopilot to fly the approach to the decision altitude.

Does this clause apply to light GA aircraft with the appropriate hardware (say a C172 with a G1000 in it), or is it limited to use by transport category/multi-crew operations?


texts: Which CPUs and programming languages are used in new airliner flight control systems?

texts:
Are the new systems of today built with the same CPUs and programming languages and development software as those of 20 or more years ago?

By new I mean that these systems are currently being designed for future airliners, or have seen service for the first time recently.

Any specific examples of new designs as used in a major latest-generation airliner (the A350 and 787 be the most obvious examples) would be better than general answers.

I'm interested in examples from any flight-essential systems (but not, for example, on-board entertainment).

As part of this question: does the industry tend to update its products through incremental updates to the microprocessors and programming languages it adopts, or does it tend to make once-in-a-generation shifts to new technologies? And, are there significant differences in the way airline manufacturers (as opposed to military/general aviation industries) approach this?


texts: Has there ever been a diesel-electric helicopter?

texts:
Occasionally I come across the diesel-electric (DE) design for submarines and freight trains. They say something like "a diesel engine powering an electric drive lets the two operate at their most efficient RPMs, and the electric drive has very little losses in efficiency."

So the question hit me: Has there even been a DE helicopter? Is there something about the DE system that makes it bad for the aviation industry? Weight maybe? But note we do not need a bunch of batteries like on a submarine. We don't need to store the power, we just convert it to electricity which goes immediately into the electric drive for the rotors.


texts: How long do airliner tires last? Can this be improved?

texts:
I imagine that the tires on commercial jets wear out pretty fast with all those squealing landings as the tire suddenly has to spin up from zero to the speed of landing.

2 questions:

How many landings does any average commercial airliner tire last before it is discarded?

Before landing, why not have a small motor assembly on the landing gear to spin up the tires to the correct speed? Surely this would avoid the degrading tire burn. The tire might last a lot longer and might even offset the cost of the motor assembly.


texts: Why are Israeli planes followed by an armored police truck at ZRH?

texts:
While I was actively traveling to Zürich (for three years before Covid pandemic), I noticed that the Israeli airplane is always being followed by an armored police car with a machine gun turret on top. The car moves parallel with the plane all the way during taxiing.
As far as I could notice, no other planes/companies had this security measurement. Does anyone know why is this happening? Are there some increased security risks connected to the planes/passengers coming to/from Israel?


texts: Optimizing the airplane for best cruising altitude and velocity

texts:
In the conceptual phase of the design, I am optimizing various entities of an airplane for the best cruising altitude and speed to reduce the cost, which also includes MTOW and fuel weight. Consider a scenario where airplane is undertaking a mission which will burn the entire mission fuel estimated. Now, in-flight it is very much likely that airplane is not able to fly at the best cruising altitude and/or speed. This will result in increase of fuel burn which might not be enough. How to tackle this problem of estimating fuel load for off-design conditions while optimizing the airplane?
One way to address this issue is to rely on the reserve fuel estimated for reserve mission such as loiter time. But, it might happen that airplane has to rely on the reserve fuel and due to increase in fuel burn during cruise, reserve fuel is less for loiter time. I don't think this is a desirable condition. Another way is to optimize the airplane for worst scenario. Now, the question arises what is that worst scenario. Is it flying at the cruise ceiling (cruising altitude and cruise ceiling are different) or something else?
Let me know how to address this problem. Thanks in advance!


texts: Does EASA allow IFR, NVFR or SVFR in gliders?

texts: Is it legally possible in Europe to get clearances for IFR, night VFR or special VFR while flying gliders? Specifically, I'm interested in sailplanes, powered sailplanes and ultralight sailplanes (MTOW below 472.5kg).


texts: I'd like to know the name of this aircraft

texts: I recognize it but can't recall the name, if anyone can tell me that would be great.


texts: Why didn't Cirrus make the SR-22's parachute steerable?

texts: After the parachute is deployed there is no control where the plane is going, so why didn't Cirrus make the SR-22's parachute steerable?


texts: Is there a list of aircraft types to be used with a callsign?

texts:
In the U.S., general aviation aircraft use the airplane type with the callsign when talking to ATC, such as "Skyhawk 123CS" or "Citation 321CT". ATC likes to know what type of airplane you're flying so they know how what its performance is.

It gets complicated with airplanes like the Cessna Corvalis, which is a Cessna (formerly Columbia) but it is faster than a Cirrus and can fly an approach at 200 kts if required. So what would the callsign of a Corvalis be? "Corvalis 123TT" or "Columbia 123TT"? I doubt it would be "Cessna 123TT".

Is there an official (or unofficial) list of airplane types to use when talking to controllers?


texts: Why does it feel like a plane accelerates just before touching down?

texts: On commercial flights it often feels like the plane gets faster just before touching down. What creates that sensation?


texts: How much thrust is gained from placing a propeller in a duct?

texts:
Assuming that the power and diameter are the same, how much extra thrust can be gained by placing a propeller in a duct? How does it influence the RPM?

To clarify: take any prop, place it in a well-designed duct, what can we expect? I expect higher RPM for same power, but also duct enhanced thrust. An approximation based on sources would be great.


texts: How much fuel does it take to start/land an aircraft, compared to normal flight?

texts: I'm wondering how bad it is to fly a short distance, such as ~50km, with a big airplane. How much less fuel does it take to fly at high altitudes compared to low? And how much of the fuel is spent on start/landing? Flying between continents is never a problem, but if a politician flies a shorter distance all hell breaks loose.


texts: Do the spinning parts of the tail mounted jet engines produce yaw on pitch changes?

texts: For example: on takeoff at rotation, would the clockwise rotation of the 2 engines have enough force to move the nose of the aircraft left? Precession would be the force, is it strong enough?


texts: Why is the Tu-95 so efficient despite having propellers that spin faster than the speed of sound?

texts:
I've ready many, many times that propellers are not efficient near the speed of sound because it's so hard to get a tip-speed above Mach 1.

Then I came across this:

It's the Tu-95 "Bear", a propeller-driven bomber whose blade tips actually move faster than the speed of sound. This is the only propeller aircraft I've ever seen whose blade tips do this. There were even reports that submarines' SONARs could hear it from a long way off because those supersonic blade tips were so noisy.

And the plane has a range of 15,000 km. That's pretty good, on par with today's huge commercial airliners.

So how can propellers be very inefficient at supersonic speeds, yet something like this is buildable on propeller-power only?

Edit: Here is the main point of my question: It seems that "all my life" I've been told, "propellers are not efficient at supersonic tip-speeds, and this is what drove the industry to jet power." And yet here is this apparent counterexample, the Tu-95. So how is this possible? What am I missing?

Here is a somewhat related question asking if helicopter blades regularly go supersonic. This is another point I've heard many times: heli blades don't do that because that would make them very inefficient. I'm assuming the rotors are effectively governed by the same laws of efficiency as a propeller for a fixed wing aircraft.

Edit: the B-52 was mentioned in comparison so here are some figures:

$$\begin{array}{|l|r|r|r|} \hline
 \text{Model} & \text{Fuel capacity [L]} & \text{Loaded weight [kg]} & \text{Range [km]}\\ \hline
\text{B-52} & 181,610  & 120,000  & 16,230 \\ \hline
\text{Tu-95} & 95,000  & 171,000  & 15,000 \\ \hline
\end{array}$$

This to me says the Tu-95 is very much more efficient, because it has significantly more weight and significantly less fuel capacity, yet has about the same range.


texts: What is typical sink rate of sinking air, and the typical rate of climb for a glider with a sustainer engine?

texts:
What is the typical rate of climb for a glider with a sustainer engine with only lift provided by the engine (no thermal lift, ridge lift, etc.)
I understand a self launching glider is almost like a modern ultralight with motors in the 80 Hp range. That probably puts the rate of climb at 400-600ft/min for a weight of 1,200lbs.
In Canada, the light aircraft specifications for homebuilt type aircraft specify a minimum rate of climb of 300 ft/min, which is at the low end of what many modern  homebuilts are capable of, at least those with around 80 Hp engines.
I understand gliders with sustainer engines are meant to "sustain altitude" and cannot self launch. I'm told they are typical about 20 hp.
Yet, what happens if you are gliding over a flat farming region just prior to sundown, thermal lift is long gone and you are "in sink", i.e. in a sinking air region with 100 ft/min sink, and your glider can only climb at 50 ft/min.  This means you're going down at 50 ft/min, no matter what. Having said that, I understand sink typically stops several hundred feet off the ground, which means you won't be slammed into the ground by the sink, but it also means you would have to fly below 1,000ft obstacle clearance and less than 1,000 ft above ground level ( AGL)
I'm sure there is a typical sink rate of descending air over fields and a typical rate of climb even for sustainers.  Just wondering what those two values are.
I would imagine that the typical rate of climb of sustainers is engineered to be above a typical rate of descending air in sink.


texts: What is the difference between a private and a commercial flight according to the US Customs and Border Protection?

texts: From what I understand, whether or not a flight is classified as private or commercial in the eyes of US Customs and Border Protection (CBP) has nothing to do with the Federal Aviation Regulations (FAR) flight rules that they are operating under. For instance, I understand that I can legally be operating under FAR Part 91 and still be a commercial flight in the eyes of CBP. What then is the determining factor?


texts: Can a mistake of a single air-traffic controller cause a collision between planes?

texts:
I am watching season 2 episode 13 of Breaking Bad and in the episode it shows that:

  an air traffic controller, distraught from his daughter's death,
  causes a mid-air collision, resulting in debris and human remains
  raining down onto the Whites' residence, as well as the rest of
  Albuquerque

It is at the very end of the episode and it looks like he has done nothing malicious just forgot to tell something. To me this sounds really surprising that a single human error can cause such damage.

As a programmer, I know that most of the scenes about computers depicted in the movies are complete nonsense. Is this a similar nonsense about aviation or is this really possible?


texts: Why are the toggle switches in cockpits of new aircraft painted white?

texts:
The toggle switches in the cockpits of new aircraft are painted white. e.g. 737 MAX:

but a 727

Why?


texts: What medications for depression are approved by the FAA?

texts: I understand that there may be additional medications on the approval list.


texts:
I am currently trying to understand the ground roll and climbing stage of normal aircraft.
I came across this formula which is an expression of the airplanes drag:

$X_a = c_{{x}_a} S \frac{\rho V^2}{2}$

where: $ c_{{x}_a} = c_{x0} + A c^2_{x_{a}}$

S: wing area
$\rho$: air density
V: velocity
$c_{x0}$: drag coefficient when the lifting force = 0
$c_{x}$: drag coefficient

A is said to be the wing inductance. Could somebody explain what is meant by wing inductance?


texts: Is there a list of what information different airlines track about their flights?

texts: It has been suggested in the media and in some answers here that airlines vary in the information they track about the status of their flights. Is there a publicly available resource that lists what information different airlines have about the location and status of their flights? For example, could a British Airways flight over the Atlantic or the middle of the Pacific have "vanished" in the same way that the Malaysian flight over the Gulf of Thailand?


texts: How to understand "Stage length, for payload calculations includes 85% wind"?

texts:
Reading "Long Range Aircraft-AEA Requirements".

In appendix, Para 1.2 "Definitions and specifications", the definition for "Stage Length" states

  Stage length [...] for payload calculations includes 85% wind.

What does that mean?


texts: What are the largest airports in terms of size, gates, and stands?

texts:
What is the largest airport in terms of:

Size of developed area?
Size of all terminal area?
Total number of gates?
Total number of gates + remote stands?


texts: Are taxiing aircraft to hold short of taxiway hold short markings if not instructed by ATC to do so?

texts: At some airports, some taxiways have taxiway hold short markings (single dashed yellow lines against a black background). Do taxiing aircraft by default need to hold short of these markings if they're not instructed by ATC to do so?


texts:
There is this question but I am hoping for more general answers to why airships are not more commonplace.

The previous question does bring up the cost of production (mainly because of hi-tech fibers used in body construction) and the high capital costs for constructing hangars for these airships.

However, civilization did operate fleets of these before and I'm just not certain why they have not 'come back' in a meaningful way. For instance, here are just a few uses that I can think of off-hand:

For tourism! Instead of a water-bourne cruise tourists can literally sail all over (I'd pay for that!)...
As the previous question implied, they can be used to carry cargo vast distances (although I am unsure if there is any real economic advantage here).

I know we use them in a small way for various things (military, sports, etc) but why are they not more commonplace?

I imagine the answer is mere economics but at the same time I feel there should be a market if for nothing else than tourism.

No one has really touched on the possibility of a cruise ship style airship. We have mentioned brief aerial tours but I'm talking about a semi-luxury week long trip in one of these things over very remote areas such as Alaska or the Siberia or even a desert... I realise there would not be room for all the luxuries of a cruise ship (pool, casino, etc) but I image about the same luxuries as a small yacht...

I imagine there are a lot of issues with long trips but can airships make unimproved 'port calls'? IE can they just set down for a few hours to let the passengers stretch their legs?


texts: Why are most runways laid out in a generally East-West direction?

texts: Runways are named by a number between 01 and 36, which is generally the magnetic azimuth of the runway's heading in decadegrees. From what I have read, most airport runways are aligned along an East-West corridor. Why is the North-South direction rarely used?


texts: Is there a term for the general design used in most modern fighters?

texts:
Is there a term that encompasses the overall design of modern fighters (e.g. F-15, F/A-18, F-14, Su-27, Su-30,33,35,37, Mig-29, J-11, etc.), with dual vertical stabilizers, leading edge extensions, dogtooth extensions, very similar nose and canopy shape/profile, air intakes, dual engines, and so on?

I know they each fit into one or more of the air superiority, strike fighter or interceptor categories, but I'm looking for a term (if it exists) which describes and/or encompasses this particular design style. Or is "modern air superiority / tactical / strike fighter" as close as I'm likely to find?


texts: Why does the CF6 have a lower bypass ratio than the TF39?

texts:
The General Electric TF39, which powered the original C-5 Galaxy, was the very first high-bypass turbofan brought into mass production, with a previously unheard-of 8:1 bypass ratio.  Yet, when it came time to make a civilian version of the TF39 (what would become known as the General Electric CF6), GE cranked the bypass ratio back to under 6:1 for the lowest-thrust version, and to 5.31:1 or lower for the beefier CF6s.

Why did GE decrease the bypass ratio of their engine, rather than increasing it further?


texts: What is ATR Automatic Thrust Restoration in MD-83?

texts: What is ATR Automatic Thrust Restoration  in MD-83 ?


texts: Was the Coanda effect known in 1868 to Matthew Piers Watt Boulton (the one who described the first ailerons)?

texts:
Matthew Piers Watt Boulton is known as the inventor whose 1868 British patent No. 392 nullified any claim of the Wright brothers that they discovered the ailerons (see FIG. 5-7).
It seems now that another invention in the same patent (see FIG. 1) shows an engine similar to one that uses the Coanda effect (see the picture: "Diagram of a generic engine that harnesses the Coandă Effect to generate lift (or forward motion if tilted 90° on its side)" for comparison).

The question is: Did Boulton have really in mind the Coanda effect when he proposed the engine in FIG. 1?

This is the explanation Boulton gave to FIG. 1:

"A body is provided having the form of a solid of revolution tapered at the stern and prow on front. An annular jet of aeriform fluid is caused to issue at its fore part in front of its convexity so as to mix with air and create a mixed stream which flows or sweeps over the convex surface, finally quitting it backwards. In this case the action of the jet causes reduction of pressure on the front and thus produces propulsive effect."

"Figure 1 is a longitudinal section of a body or vessel constructed according to my Invention, propelled by an annular jet issuing at its front. a is the body or vessel containing fluid under pressure and shaped so as to offer little resistance to longitudinal movement in the direction of the arrow e; b is a tapering front or prow connected to a by thin ribs; and c is a cavity so formed with an opening round its periphery that an annular jet of fluid can issue by it perpendicularly to the longitudinal axis of a or nearly so. When the jet so issues it tends to reduce pressure on all sides. By virtue of this reduction of pressure the air (or other medium in which the body is placed) in front being free to move flows backwards towards the jet and mingles with it, while the body a being also free to move, moves forwards in the direction of the arrow e. The jet instead of issuing from c perpendicularly to the longitudinal axis of a may be made to issue at any desired angle by suitably forming the passage round the periphery of c."

FIG. 1 shows an engine that seems to use the Coanda effect and FIG. 5-7 a wing with ailerons (driven by a pendulum but the patent specifies they can also be controlled by hand).
The entire patent of Boulton can be consulted HERE

A diagram of a generic engine that harnesses the Coandă Effect to generate lift (or forward motion if tilted 90° on its side).


texts: Why photographing airports is banned if everything is perfectly pictured in Google Maps?

texts:
While staying at Premier Inn, next to Abu Dhabi International Airport (AUH/OMAA), I was more than surprised to find out warning signs that I'm strictly prohibited from taking photos of the nearby airport form the hotel's roof pool.

Can someone explain me, why such regulations are still in place or how do they aid to airport security, if everything (what I'm banned from photographing from this distance) is perfectly pictured, in a far better details, in Google Maps?


texts: What are the disadvantages of a tailless ultralight design?

texts:
What are the disadvantages of a tailless ultralight design with say 20 deg swept back wings with wing tip rudders, 20-60mph, max 25 hp?

I'm not an aerospace engineer, so I stand to be corrected:

The only 2 disadvantages I can think of are:

Increased wing area/more weight/stronger spar

I understand the wing area would need to be larger as the "aerodynamic wing span" would be smaller than the physical wing span. I understand the wing only produces lift with the velocity component perpendicular to the leading edge ( which I understand would be V0*cos(radians(20)))

Possible reduced or no side slip angle.

I understand you're not supposed to side slip a Velocity aircraft as the leeward wingtip vertical tail may stall ( rudders only move outward). I understand only the right rudder deflects outward when turning right ( the left rudder acting only as a vertical stabilizer, in this case) I'm attributing this to too thin of a vertical tail airfoil ( low stall angle ) with too high of an aspect ratio. ( I stand to be corrected on all the above). I understand Velocity reduced this problem by reducing the max angle of rudder deflection.

Are there any other disadvantages in terms of stability, cross wind landing, etc?

See pic below of the Mitchell Flying Wing:


texts: What are the requirements for grass height around runways and taxiways?

texts: I am looking for the requirements for grass heights around runway and taxiway edges, signs and lights?


texts: Listening to KSEA, what does orange, green, or blue line mean?

texts:
I'm listening to an LiveATC stream for the Seattle Tacoma airport.

I keep hearing things like "push approved on the blue line".

I'm pretty sure I've heard orange, blue, and green as colors.

What does this mean?


texts: What twin engine is this USAF-painted plane?

texts:
I keep trying to identify a group of aircraft, what bimotor is this plane?

(photos: own work; click to view)


texts: Would it be a viable option to make the engine generate lift?

texts: I was thinking that if you made the engines generate lift it might help a tiny bit with the amount of time to takeoff, and thus lowering runway lengths.


texts: Are there any places I can take an FAA written test in Japan?

texts:
I want to ask FAA in person. But, I was not able to reach them. I tried phone call 8668782498, sent e-mail to local FSDO. But nothing coming back.

I guess I have some possibility to take it in military base placed in Japan.
Do you know something about this?


texts: Constant speed propeller blade pitch compared to fixed-pitch

texts:
I just transitioned to a complex airplane (Piper Arrow II). While I get how to use the Manifold Pressure / Propeller levers, I still find myself trying to piece together how all the components would function in a given situation.

One such situation is with the prop lever full-forward. If you back off the manifold pressure with the prop full-forward, the RPM will drop because there isn't enough air / fuel for the engine to turn at a the request rate. Think coming in to land (prop full toward and start reducing manifold pressure).

My question is: Does the propeller flatten out (relatively speaking) more than in a fixed-pitch propeller aircraft in this situation or is it the same net effect as operating a fixed-pitch propeller plane?

I've heard that putting the prop full-forward and then just using the throttle is the equivalent of operating a fixed-pitch propeller plane. How accurate is this statement?


texts: When to reduce power on takeoff (Cessna 182 or similar)?

texts:
There are two sides I've heard when taking off in a Cessna 182 or other small airplane with a normally aspirated engine driving a constant speed propeller:

  As soon as your wheels are off the ground... Or,
  When you're 700-1,000 feet off the ground...

  Reduce to about 23" of manifold pressure and then reduce the RPM to 2,450 (or 2,300) depending on the plane.

The POH or Owner's Manual (in my case a 1972 Cessna 182P) simply says Full Power under the Normal Take-Off procedure.

The reasoning I've heard is to try not to over-stress the engine (whatever that means exactly), but on the flip side, I've heard that if an engine is going to do something funky, it's probably going to happen when you do a power reduction, or otherwise do something.

I personally want all the power I can have until I'm far enough off the ground to have options if the engine quits or sputters (turn back if high enough, or glide to a suitable spot if not).

I'm asking is there an "official procedure" as to when you should perform this power reduction (inches off the ground or 700-1,000 feet), and if so, have there been actual studies that say why one way is better than the other, or is this one of those groundless, "endless debates" that are so prevalent in aviation?


texts: How often are heavy aircraft brake pads changed?

texts: How often are Boeing 747-800 and Airbus A380 aircraft brake pads changed?


texts: What is the purposes of grid-like pattern route for small aircraft?

texts:
In these days, I see small aircraft like P68 fly with a very accurate "grid-like" pattern. I'm sorry but I don't know the correct word. Here a couple of examples, grabbed today at the same time:

and

What kind of job they might do with these routes?
I don't think it's about agriculture because the patterns are too long and they fly over cities and sea as well (and I don't think this kind of aircraft is the most suitable for such a task).

I thought about observation of restriction for COVID-19, but I would use helicopters instead of aircraft, and again the patterns are so long for just be sure if anyone goes out for a walk.

Any sort of collecting photographic data? Like Google does for its Maps?


texts: What are the standards on displaying Crew Awareness Messages?

texts: Are there any standards on where in display Crew awareness system messages needs to be shown and how many messages at a time needs to be displayed. I checked SAE ARP4102-7 but I didn't find any guidance.


texts: Can I Return Back to the Destination Airport after I Diverted to the Destination Alternate?

texts:
Can I Return Back to the Destination Airport after I Diverted to the Destination Alternate (while enroute to the destination alternate)?
I highly appreciate an answer with reference please.


texts: Does temperature affect dynamic pressure?

texts:
Taking off on a cold day (5°C), it can take 10 seconds to reach rotation speed but on a hot day (40°C) degrees it will take longer to reach the same speed.

Is this due to the dynamic pressure? How does temperature affect it?


texts: What is "settling with power" and how does it differ from vortex ring state?

texts:
I've always heard these terms used interchangeably. I figured that "settling with power" was what the pilot did to cause the vortex ring state (VRS). But comments on another question indicate that they are two entirely separate aerodynamic phenomena.

I understand VRS, so what is settling with power?


texts: Do US military aircraft have tail numbers beginning with "N"?

texts:
Military aircraft usually display a serial number along with other insignia on the tail or body of the aircraft, as described here.  However military serial numbers are not the same as FAA tail numbers on civilian US aircraft, which begin with the letter "N".

Do military aircraft also have an "N" number, or do US military aircraft simply not have an "N" number?


texts: Why do lavatories in modern planes still have ash trays?

texts: Last week I flew on a modern B737-700. I noticed that the lavatory was equipped with ashtrays  (both on the inside as on the outside) even with the smoking sign on it. Smoking on airplanes has been banned from quite some time now, so why are lavatories still built where ash trays are provided?


texts: How to deal with turbulence while flying glider? (Cautions in applying rudder)

texts:
I just watched video explaining how the American Airline Flight 587 crashed

It led me to think about glider flying. The cause of that crash was that the first officer aggressively and unnecessarily applied full rudder left and right in turbulence, the air force against the moving rudder stressed the vertical stabilizer and caused it to snap.

Is such risk realistic in glider flying? If one encounters air turbulence in while flying glider, how to deal with it, and what to avoid?


texts:
I was going through social media and I came across this GIF image that showed a plane doing some sort of roll.

It was labeled "Barrel Roll" but in the comments to the post, someone said that it was an "Aileron Roll". What is the difference between a barrel roll and an aileron roll?


texts:
What biplane is this a model of?
What biplane is this a model of?


texts: I have seen this part on a me 262 model kit but I don't know what it is... I've make some research on it but I find nothing! Maybe it can be radar, or a weapon? Do you know what is this? And also its function?


texts: Why is the Tu-204 virtually immune to wing and tail icing?

texts:
Atmospheric icing is extremely hazardous to heavier-than-air aircraft, as it badly disrupts their ability to generate aerodynamic lift (the inherent roughness of accreted ice encourages the airflow to separate from the upper surface of the wing, causing the aircraft to stall at a much lower angle of attack, and a much lower lift coefficient, than it would otherwise) and greatly increases aerodynamic drag (the rough, non-streamlined surface of the ice has much the same effect on the aircraft’s motion through the air as gluing a big sheet of 00-grit sandpaper to your butt would have on your motion down a playground slide).  As such, built-in anti-ice equipment (generally consisting of heaters using either engine bleed air or electrical-resistance heating elements, or of pneumatic deicing boots that mechanically dislodge ice) is generally a must for the wing(s), tail surface(s), and propeller(s) (if any) of airplanes intended to fly in icing conditions, in order that any accumulated ice can be melted or broken off before it can significantly affect the aircraft’s aerodynamics.  If these systems are inoperative, the aircraft must not be flown in icing conditions until its anti-ice capability is restored, and aircraft lacking these systems are generally forbidden from entering ice altogether.
The Tupolev Tu-204 is an unusual exception to this.  Its wing and tail surfaces are (supposedly) so resistant to ice accumulation that it can fly in heavy icing conditions without needing to be equipped with wing or tail anti-ice equipment:

...The wings and tails are relatively resistant to ice build-up, and as such anti-icing systems are not equipped.  Among today’s airliners the Tu-204 is the only one which does not require wing anti-icing systems.  During the test flight safety has been confirmed without the anti-icing system on the bearing surfaces and the aircraft obtained Russian and European certificates...  [Wikipedia, “Tupolev Tu-204”, section 1.1 (“Technology”).]

This seems like a rather suspect claim; atmospherically-generated ice has the well-documented tendency to stick to essentially whatever it hits (as long as it’s not warm enough to melt the ice off), no matter what its composition, shape, or surface texture.  Even if the Tu-204 goes the usual route of making the tail bigger so it works fine even when iced, this doesn't explain how they can get away with non-anti-iced wings; how does the Tu-204 supposedly manage to do this?


texts: What is the easiest way for a new private pilot to visit Manhattan?

texts:
As a goal, I would like to:

Limit the difficulty of the class B airspace by staying at uncrowded areas
Minimize the time it takes to get into the city


texts: What is the difference between fail-safe and fail-soft?

texts:
I have heard the following terms related to safe system design but I cannot really see a difference between fail-safe and fail-soft (graceful degradation).

To get a common understanding I will just write out the terms that I've heard. Please feel free to correct me, if I don't explain something properly:

Safe life: A system does not show any fault during its lifecycle
Fail-Safe: A system goes into a safe operating mode with reduced functionality after a failure
Fail-Soft: A system goes into a degraded mode after a failure
Fail-Operative: A system still has the full functionality after a failure

From those explanations, it seems to me that Fail-Safe and Fail-Soft are actually the same concepts. I would be glad if someone could explain to me the difference between the concepts by using some examples from aviation.


texts: In the US, do ultralight aircraft have tail numbers?

texts: Just wondering if ultralight aircraft in the United States have tail numbers like the larger general aviation aircraft have?


texts: Why did an iPad software failure cause a return to the gate?

texts:
I was amazed to read this which implies that a software failure on iPads caused departing flights to return to the gate.
I used to be an avionics engineer up until a point before the current generation of consumer electronics and now develop "field" apps for phones and tablets.  I know two things to be true.

Consumer phones and tablets of all persuasions used in field applications have nowhere near the reliability of certified avionics.  I own an iPad, amongst many
other devices, and it does not get close to six nines reliability (as do
none of my other consumer devices).  In particular, since the latest iPad updates over the last year or two, it's been quite buggy.

The hardware is not designed and built to the standards required for avionics and, without appropriate hardware, the
software cannot be to aviation standards either.

I know that these devices have been certified for use and I know why and what they are used for but I thought they were only convenience devices.  It seems that they have become part of the safety chain.
Are they MEL items?  Does anyone know what's really going on here?


texts: What is the purpose of multiple autopilots?

texts:
I have read that some airplanes have multiple autopilots, specifically airliners.

What is the reason for this, and how does that system work?


texts:
I have some questions about ATA 21, how packs works?... I mean, what's inside them?, what are their mechanims? And How the warm air becomes into cold air?. (On a airbus A320)

I'm starting my major at aeronatics and i don't have any idea about ATAs.
I couldn´t find clear information about it on my lenguage, But found this forum and i hope that somebody can help me.

Thanks.


texts: What are the applications, advantages and limitations of Gyrodyne rotorcraft?

texts:
Gyrodyne is a VTOL rotorcraft. It has ability to power both rotors and propellers for generating lift and thrust. What makes it of lesser popularity than helicopters. Are there any applications of Gyrodyne?

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


texts: Can thrust reversers alone steer and stop an airliner?

texts: Is it possible to use ONLY thrust reversers to steer and bring a smaller size commercial jet aircraft, with a minimum amount of fuel onboard, to a complete stop, after touching down on a longer than average length commercial airport runway?


texts: Why are the F/A-18 rudders deflected in opposing directions during takeoff?

texts:
Looking at some videos and photos of F/A-18 Hornets and Super Hornets taking off from carriers and from airfields, I recognised that the left rudder is pointing right, and the right rudder pointing left.

Here's a picture:

Why is that? Are there any aerodynamic advantages?
Is it also used as an airbrake to slow the plane down at landings?
At which point of the flights are the rudders in this position and why? (Takeoff, landing, cruising, or both?)
Does the pilot steer them or is the work done by a computer?


texts: What is the difference between component service and inspection?

texts: What is the difference between component inspection and component service? And is overhaul / restoration a service or an inspection?


texts: Do fuselage rip/crack/damage sensors exist?

texts: Are there sensors that can detect a rip, crack or damage in the fuselage skin by not using air pressure differential on aircraft?


texts: If the speed of wind at ground is 200 kn, could an Airliner land vertically if it's course is opposite to the wind's direction?

texts:
I'm not a pilote and my field is programming, but I was thinking about that question:
If the speed of wind at ground is 200 kn (just an example), could an Airliner land vertically (per reference to ground) if it's course is opposite to the wind's direction?


texts: What is the best design for a small flying wing with special flight envelope?

texts:
I'm designing a small, light and portable flying wing UAV that will launch and land vertically via a Tilt-rotor system. I'm attempting to use the program XflrV5 but am having difficulty understanding the numbers. I'm a design and electronics guy, but a poor engineer.

The craft has a span of 6', root chord of ~8". Since it is a VTOL it does not need to fly slowly - below 15-20 MPH. I would like a top speed of ~100 MPH. the end product will be likely built with carbon fiber so compressibility shouldn't be a problem. After some reading I am tentatively using the s5020 airfoil but I'm not married to it.

My primary priority is forward flight efficiency, second priority is reasonable stability as it for recon use (forest fires, search/rescue military) but this can be mitigated by use of a stabilized camera gimbal. Maneuverability is a low priority if it has to be to accommodate the above items.

My question is with these parameters what type of wing design would work best and would sweep and twist be needed considering the speed envelope?

A UAV with a similar envelope would be the Boeing Scan Eagle as it is catapult launched and flown into a net for retrieval.

-------------------EDIT 1 -----------------------

I have included some pics of possible designs  to help show some ideal designs to meet the portability requirement. Note: the outer 2' (660mm) of the wing will be removable for portability.

It would be a great help to hear your opinions which would be best.

-------------------EDIT 2 -----------------------

A similar model to mine is the Firefly6... mine will have some improvements as well as a different market. I forgot to add that the AUW will be 6 - 7 lbs. (~3Kg)


texts: What is the correct formula to calculate propeller efficiency?

texts:
How to calculate in the right way the efficiency of a propeller?

If we know the engine power, speed of the plane and the thrust of its propeller, what is the correct method, (1) or (2), for calculating the efficiency of the propeller?

Assuming that Method 1 is the correct one, it appears that the efficiency of a propeller must satisfy the inequality:

Update:

It looks like Method 1 is correct and 2 is wrong as long as the page Performance of Propellers, MIT calculates the efficiency on an ideal propeller and gets the same inequality.
If a propeller of diameter, d, delivers the thrust, T, while the plane travels at the speed, V, it always has a maximum possible efficiency that can be calculated, is below 1 and can not be improved. Not even an ideal propeller of diameter, d, has, in general, an efficiency that reaches 100%. The absolute minimum, reference power, is always $TV$ and not something else and the efficiency is always:
$$TV/Power_{absorbed}$$
where the minimum absorbed power is calculated with Froude's Propeller Theory.


texts: How do friendly stealth planes locate each other?

texts:
Stealth planes can't be seen (very well) on radar. So one stealth plane should be unable to locate another stealth plane on its radar and vice versa.

So how would one stealth plane locate another, friendly, stealth plane?


texts: Why was the DC-9-80/MD-80 so successful despite being obsolete almost from birth?

texts:
The McDonnell Douglas DC-9-80/MD-80 series of narrowbody jetliners was the second-to-last DC-9 major version produced (from 1979 through 1999), the second-largest, the most-produced (just under half of all DC-9s ever produced were of one of the five DC-9-80 minor versions), and the last to be powered by the Pratt & Whitney JT8D low-bypass turbofan.

By 1985, however, the JT8D was already obsolete, with the first small-to-midsize-narrowbody-sized high-bypass turbofans having entered service in the first half of the 1980s, simultaneously offering greater fuel efficiency and lesser noise than the old, outdated JT8D.  Yet, despite this, the DC-9-80 only got more successful as the 1980s wore on and rolled over into the 1990s, with the single best year being 1991, and the years from 1987 through 1992 accounting for over half of all DC-9-80s produced.

Why and how was the DC-9-80 able to be so successful in the late 1980s and onwards, despite its 1960s-era engines rendering it obsolete just a few years after it entered service?


texts: Do bluetooth aviation headsets and/or music negatively affect safety?

texts:
I'm in the process of getting my private pilot's license, and I've come to the point where it's probably time to think about buying a headset.

As I understand it there are a few options ranging from a standard mic and speakers, to passive noise cancellation, active noise cancellation, and even bluetooth for use with iPhones/MP3 players, which I think is awesome, however I'm concerned about distraction while flying.

Has listening to music and/or noise cancellation been at all shown to increase pilot error?

My main concerns are

What if I have a noise cancelling headset on, and the engine undergoes detonation, or what if the aircraft does something I should be alarmed about based on auditory cues that I can't hear?
Same situations as above, but even worse because I'm rocking out to some sweet tunes, is there the possibility that having music will exacerbate the aforementioned issues, or what if ATC comes on, and I hear them, but I don't register what they say because I was jamming to some Kenny Loggins?

Additionally, are commercial pilots permitted to use bluetooth headsets for phone calls? For music? Do crash statistics indicate that music and flying leads to more pilot-error? It certainly can't help...


texts: If the "Fuel Shutoff Valve" is ON, wouldn't fuel be cut off?

texts:
Ok, so this may be more of an english lanugage question, and I can confirm from context that when the fuel shutoff valve is ON fuel does indeed flow to the engine, but wouldn't that just make more sense to call that valve the fuel valve?

If the component that shuts fuel off is on, operational, in use, functioning, etc., shouln't fuel be shut off, as the name implies?

I realize this could be seen as a quibble, but confusion causes accidents and IMO this is wildly confusing.

EDIT

Looking at the Cessna 152 checklist today I noticed this interesting quirk. On the regular checklist side (pre-takeoff, maneuver, etc.) the checklist reads "Fuel Shuttof Valve - ON", but on the emergency checklist for an engine fire it merely states "Fuel Valve - OFF".


texts: What is the difference between climb angle and flight path climb angle?

texts:
Consequently, which of these two angles does wind affect?

Thank you everyone!


texts: I'm a student pilot and am thinking about putting a tasteful decal on my log book, if for no other reason than to identify it as my own.  Is that OK, or would that be frowned upon?  Thanks.


texts: Are nearest VOR stations always tuned to?

texts:
I am flying under IFR.

My current leg route is Z401. I am between TIPRU and VOR VLM (VLASIM). I am on inbound radial 304° VLM:

This is an RNAV route. But let us imagine it is non-RNAV and I am flying a non-RNAV plane.

On the NAV1 receiver I tuned and checked I have VLM.

I have a spare NAV2 receiver. Should I tune on NAV2 the nearby VOR VOZ (VOZICE)? If yes, why?

I assume not, unless I am flying  RNAV plane which will utilize it as source of position. Even then I am not sure if I should tune it.


texts:
What is the meaning of the track info found on Flightradar24, as seen below?

Would be the angle between the route and the equator?


texts: How can I know if North Atlantic Tracks have been amended?

texts:
Information about the North Atlantic Tracks is issued through Track Messages. The NAT Doc 007 document states that every track message is identified by the TMI (Track Message Identifier) number:

The originating OAC identifies each NAT Track Message, within the
Remarks section appended to the end of the NAT Track message, by means
of a 3-digit Track Message Identification (TMI) number equivalent to
the Julian calendar date on which that OTS is effective. For example,
the OTS effective on February 1st will be identified by TMI 032. (The
Julian calendar date is a simple progression of numbered days without
reference to months, with numbering starting from the first day of the
year.).

In case the North Atlantic Tracks are modified, a letter is appended to the TMI number:

If any subsequent NAT Track amendments affecting the entry/exit
points, route of flight (co-ordinates) or flight level allocation are
made, the whole NAT Track Message will be re-issued. The reason for
this amendment will be shown in the Notes and a successive alphabetic
character, i.e. ‘A’, then ‘B’, etc., will be added to the end of the
TMI number (e.g. TMI 032A).

I would like to know how such change is notified to the interested parties; is some ATCs issuing a NOTAM to declare that some changes have been done to the TM? If yes, where can I visualize such NOTAM?
One possible way to overcome my problem would consist in constantly checking if the TMI number has changed but this is not a very efficient way to proceed. I would rather expect some NOTAM which notifies the TMI number change.
Can you tell me if what I ask is plausible? If yes how can I proced?


texts: Will the landing gear work mechanically in case of total power loss?

texts:
In case of a total power failure in all the aircraft systems like engine failure and APU failure, would it be possible to use mechanical means (manually) to open the landing gear bay door and deploy the landing gear through mechanical means?

I know it’s possible to glide the flight if the engines failed. But, wondering how they land.


texts: Can a safety pilot acting as PIC also log cross country time?

texts:
I am working on my instrument rating and I need to build up both my instrument time and Cross Country time to meet the requirements.  I am planning on making most of that time by flying with a friend who I will switch off between hood time and safety pilot.  We are planning on doing lots of cross country hood time to meet our hours.  Also the safety pilot will be designated PIC so that we can claim PIC time as safety pilot.

We need to build 50 hours PIC cross country time so my question is can the safety pilot, if they are designated PIC for the flight, claim cross-country time even if they are not touching the controls for that flight?


texts: Why do pilots normally fly by CAS rather than TAS?

texts: I think I know the answer to this question, but I want to confirm. Airline pilots normally fly a CAS/Mach profile, which means that above the CAS/Mach transition altitude they fly by Mach, and below it they fly by CAS (calibrated airspeed). Why do they fly by CAS rather than TAS (true airspeed)? My guess is that they use CAS because that is what their airspeed instruments show naturally, whereas TAS requires computation to determine. Is that right? Or is it also because it helps to slow down in descent and speed up in climb (since a constant CAS in climb corresponds to an increasing TAS)? Thanks.


texts: Does the reference for AGL include obstacles?

texts:
Let's say a plane flies 10m above some trees, that themselves are 10m above the underlying ground. Would that be 10m or 20m AGL?

Or, in more abstract terms: What exactly is the reference point for AGL? The actual ground that you would stand on as a pedestrian? The point where you would first impact something (even if it's just a very lightweight sprig)? something else?

How does it work with objects like high bridges, that you could fly below but could still impact on a higher altitude?


texts: When receiving a TCAS RA, DESCEND DESCEND, and starting the descent, if a pilot received GPWS warning, TERRAIN, what would they do?

texts: The TCAS warning says: " DESCEND, DESCEND" and immediately after the crew receives: "TERRAIN, TERRAIN", what would they do?


texts: When and why is the SELCAL (Selective Calling Radio System) check being performed?

texts: When and in what scenario is the SELCAL (Selective Calling Radio System)  check being performed by crew?


texts: What are the advantages/disadvantages of in-fuselage engines (eg most fighter jets) vs wing/fuselage mounted engines?

texts:
Most modern jet fighter designs incorporate their engine(s) within the fuselage, while most other medium/large aircraft mount them either under the wings or on the rear fuselage.

What are the advantages and disadvantages of in-fuselage jet engine placement, compared to those mounted on the fuselage or wings of an aircraft?


texts: Why would an airport use an L/R runway combination and a second number instead of L/C/R?

texts: At KPHX, there's a Runway 25L/R and a runway 26. What would the reasoning be for using this instead of what seems to be the more common L/C/R designation?


texts: What is the standard for tachometer calibration / Hobb's equivalency?

texts:
I've heard that 1 tach hour = 1 Hobb's hour at maximum RPM.  I've also heard that tach equivalency is at "cruise" RPM, although that seems vague.

I believe I've also heard that the accuracy of tachometers is regulated (I think to within 50 RPM).

Because engine time, and often TTSN, is measured by tach hour, there surely must be a strict standard for each aircraft for what RPM the tach counter should be set to.

What is the standard for tachometer calibration? Max RPM? Cruise RPM? Something else?


texts: What is the width of seat tracks on airliners?

texts:
I've been scouring the internet for the track width of seats in airlines, and can't find anything on it. Does anyone know around what that dimension might be?

I'm not looking for the dimensions of the seats themselves, but the width of the tracks that the seats attach to.


texts: In reference to airspace, what does the FAA mean by "within the lateral boundaries of"? Is this construed to also imply a vertical limit?

texts:
Several FARs use the phrase "within the lateral boundaries of" (x airspace).  What does the FAA interpret this phrase to mean?  Specifically, what is the vertical extent of the airspace encompassed by this phrase?

The common-sense interpretation of this phrase would appear to include any airspace whose latitude-longitude coordinates fall within the boundaries of said airspace, regardless of altitude, from the earth's surface all the way to outer space, or at least to the upper limit of the airspace which the FAA has any regulatory authority over.

Otherwise, it would seem to serve just as well to dispense with the "within the lateral boundaries" phrase and simply say "within" (x airspace).

Is there any evidence that the FAA interprets "within the lateral boundaries of" differently than the meaning noted above?

The answer to this question affects the interpretations of certain FARs, describing, among other things, airspace where ADS-B-out is required, airspace where 3 miles visibility is required to enter a traffic pattern under Visual Flight Rules with no special VFR clearance, airspace within which aerobatic flight is prohibited, airspace where prior authorization is required to operate unmanned free balloons, and airspace in which an ultralight aircraft may not be flown without prior authorization from ATC.


texts: Is it dangerous for a supersonic aircraft to fly at exactly Mach 1?

texts: If a plane that is designed for supersonic flight, say the Concorde, kept flying at exactly the speed of sound, would there be any danger in that? If so, what could get dangerous at constant Mach 1 flight and how long can a plane survive in flying at Mach 1?


texts: In an ATIS broadcast, is the visibility in statute or nautical miles?

texts: I think I remember seeing somewhere that since it's an observation at the surface, statute miles are used for the visibility. Would be nice if someone had a reference.


texts: What is the minimum speed for a scale-model of a modern commercial aircraft to fly?

texts:
Suppose a commercial jetliner (say an Airbus A320 or Boeing 737) were scaled down into  a remote-controlled drone, so that its wingspan were two feet wide. My questions regarding this scale-model are:

1) Would jet engines work if scaled-down to such proportions?

2) Would the wings, tailplane, ailerons, flaps etc. work if exactly scaled down in the same ratio as the fuselage?

3) At what velocity should the scale-model taxi in order to take off?

4) At what speeds should the scale-model fly to achieve stable flight, if the length and breadth of the wings etc. are made correctly to scale?

5) Is it possible that the flight speed of a scale model of a commercial airliner can be scaled down to the extent that it can realistically be remote-controlled by a person on the ground in a city environment, such as a park?

6) One of the things I am asking here is: can the plane shown in this video be genuine? Or is it necessarily a hoax, made with computer graphics?


texts: Is a pilot's instinctive reaction to a stall counter-intutive?

texts:
Is the correct stall recovery action somehow counter-intuitive? I've read about crashes like Colgan Air 3407 where pilots experiencing a stall have done the exact wrong thing and pitching the nose up. It makes me wonder if pitching down does not feel right to a person.

Not being a pilot I can only relate it to driving a car. You're taught that to recover from a skid you should steer into it. An inexperienced driver will be in a turn, feel a skid and turn the wheel further into the turn resulting in loss of control. You have to teach yourself to overcome that instinctive reaction and remember what you were trained to do.

Is the reaction to a stall similar? When you feel the a/c lose lift and start dropping is it an instinctive reaction to try to climb? You're going down and you want to go up so you pull back. Do you have to teach yourself to overcome a reflex to use proper recovery technique?

If so do airline pilots practice stall recovery in a simulator? I know it took me a bit of practice in an icy parking lot to make skid recovery come naturally.


texts: Can a normal PASSENGER pilot a plane with no training?

texts:
This is an extreme question, but I am daring it because I want to.

Situation :

All pilots, officers, die.
just say no crews can pilot a plane
no former pilot in the passenger

Only option is for a normal passenger to pilot a plane. Is this possible?


texts: Which single pilot aircraft had a range of at least 2160nm in the late 90s?

texts:
I'm writing a book and looking for an airplane that can handle that distance (2160nm), was available back in the late 90s, and can be operated by a single pilot.
Thanks!


texts:
Every NetJets aircraft that I've seen has a tail number ending in QS. Knowing aircraft operators, I'm sure it stands for something, but I don't know what.

What does the QS stand for in NetJets tail numbers?


texts: What's the difference between "dumping" and "jettisoning" fuel?

texts:
There are some countries (Sweden, for example), they do not permit "dumping" fuel, only "jettisoning" procedures.
Is there any difference according to the amount of fuel that will reach the ground? And the area surrounded by the fuel released?


texts: How does an airplane move itself in the runway?

texts:
Basically do they move themselves using their powerful jet/propeller engines to propel themselves forward or do they just use an engine that powers the wheels used for landing?

I'm not really asking about planes that are readying for takeoffs just the ones that move on the ground like a car would.


texts: Is there a common route that Seattle GA pilots use to circle Mt Rainier while avoiding class B airspace?

texts: I'd like to fly around Mount Rainier in a C172 out of Renton (KRNT). What route do people usually take? I wonder if I can climb quickly enough once out of Seattle class B airspace for terrain around Mt Rainier. What do people usually do?


texts: What does the Emergency Avionics switch do?

texts:
In almost every light aircraft I've ever flown, I recall their being a rocker switch marked "Emergency Avionics". Here's an example:

It's never really occurred to me to ask an instructor/owner what it does nor when to use it. Can somebody here explain what it does exactly?

Also, it appears to always be an aftermarket addition (the switch never quite matches the rest of the panel), could there perhaps be a reason why this second avionics master was added?


texts: How loud was the Concorde's sonic boom at the ground level?

texts:
Before the Concorde was sent into retirement, their supersonic flight paths were restricted to the ocean because of concerns about sonic boom on the ground.

But just how loud was this boom? Was it significantly louder than the noise from a Mach 0.9 airplane?


texts: Is it possible to tow a smaller aircraft (like a LSA with a non-functioning engine) with a more powerful towplane?

texts: The idea is to move an otherwise flyable aircraft with a bad engine from an airstrip with no facilities, to an FBO with a AP mechanic available for an engine swap. Let's say perhaps 100-200 miles, VFR conditions, takeoff, climb to cruise altitude, descent, and landing.


texts: What does Airbus means by long product cycles?

texts:
I was reading this article. The article was about issues that Airbus may face if the UK does a 'Hard Brexit'.  At the very end of the Article though, Airbus says

  Airbus makes wings for all its jetliners in the UK. The France-based
  company campaigned against Britain leaving the EU ahead of the UK
  vote, but has said it would not make abrupt changes to its operations
  there due to long product cycles. - foxbusiness.com

Can anybody elaborate what the company means by long product cycles?


texts: Why do we need to know both groundspeed and airspeed?

texts:
As far as I understood it correctly:

airspeed: is obtained by measuring the difference in airpressure (using Pitot tubes I guess?) around the aircraft and the airpressure caused by propulsion.
ground speed: is the speed of the aircraft relative to the (immobile) ground.

Ok, I see that there are two types of speed. But why do we need both? Why not just one?


texts: What are Uses of thin airfoil and thick airfoil?

texts: I have heard that thin airfoils are used for fast fyling and thick airfoil a are used for more lift. Is it true? Can you explain specific uses of thick and thin airfoils ?


texts: How heavy is too heavy to land on a grass strip?

texts:
This is actually a tricky question, because it's not just about gross weight, but about how much weight each individual tire imparts into the ground.  This, of course, depends on the design of the suspension and the number of wheels.  Thus a really big craft, with a well designed undercarriage, can land on grass just fine (like a C-130 for example).

The point being, "how heavy is too heavy" has more to do with specific weight supported by each wheel during landing, and less to do with total landing weight.

So, kind of a two parter.  Firstly, how much weight can a grass field generally support when an aircraft is landing?  Secondly, how do aircraft designers make landing gear that can land on a grass field without plowing into the ground and ripping off?


texts: Does taking a long time to solo mean that I'll take a long time for training in general?

texts:
I have a fairly high (in my research - 80hrs and counting) flight hours and still no solo, with landings having been a major reason. There is definitely progress - but I am not convinced I'll solo before 100. I am 43 in decent shape and reasonably coordinated (no red flags).  In addition to being expensive and frustrating it begs a question whether any subsequent flying activities like an instrument rating would also take significantly longer (thus being more expensive and frustrating) and - more importantly - whether it is an indicator that my future piloting skills will always be mediocre.

My CFI says that "everyone hits a plateau" but I am concerned that past may be an indicator for future...

Couple notes to address comments
- I have passed my medical
- Hours were spread over 10 months and there was a 2-3 month lull (due to weather + ski season) in winter and 1 month break in summer.  Otherwise I was pretty religious about 2-3/week lessons.
- I actually changed CFI at about 50hr mark and quite like how my current CFI teaches

So while it would be nice to look at outside issues - I think the problem is more likely to lie with me than with others...  Now back to my original questions...

Any thoughts?


texts: Would an aircraft with contra-rotating propellers longer than the plane's wingspan be able to fly?

texts:
I enjoy taking the time to try and visualize how fictional aircraft might actually work in reality. Unfortunately there are some that seem highly impractical from an engineering student's point of view.

One in particular is the Bella Ciela from "The Place Promised in Our Early Days." It features a set of blade-like wings that protrude out front and deploy into contra-rotating propellers, sustaining flight after its jet-assisted takeoff. The blades spin much slower than a conventional propeller as well.

I can get by the closed-loop wing. The V-tail has no issues as far as I can see. My main concern is the large rotating blades that extend far beyond the wingspan of the plane. Taking the Bella Ciela's design out of the equation and focusing on concepts alone..

How feasible is it to use a propeller larger than the wingspan? Is there any law of physics that prevent this configuration?
What immediate consequences would be seen in the airflow behind such a large propeller? Would the wings aft of the flow still be able to produce stable lift?
The blades remain flat when stowed and act as an additional lifting surface; but I assume one could position them so that their loss of lift doesn't affect the balance of the plane (like in the sketch, with them centered)?
Without twist, can a propeller still provide efficient thrust? Could you reproduce the twist's effect by instead varying the length of the blade's chord from root to tip?
Are there standard equations for calculating thrust and drag of a propeller that does not have twist? Or of a propeller in general?

I can already see how drag would be a huge issue with spinning something so big. Is there a limit to how long propeller blades can get?

My apologies if I am asking [too many] questions that do not fit this board's criteria. This is just a concept that has had me Googling around for the past few hours. It's neat, and I hate dismissing things as just art without at least trying to justify them.


texts: How does an airspeed indicator look from the inside?

texts: How does a typical GA airspeed indicator look from the inside and how does it work?


texts: Where is the 36 month ATPL theory exam validity before CPL/IR test listed and described?

texts:
The provider of my EASA Integrated Training Course states that my ATPL theory exams are only valid for 36 months before a CPL or IR skills test.

Where is this regulation listed and described?

Additionally, is this from the date the ATPL theory series is completed, or when the earliest ATPL exam is completed? Finally, do both the CPL and IR skills tests both have to be completed within 36 months, or, just the CPL?


texts: What is the optimal way to climb fastest between two points on a Cessna 172N?

texts:
Cessna 172N’s POH has Vx = 59 Knots.

Let’s assume you need to climb from 1000 msl on traffic pattern just after you finished turning cross-wind and are clocking 85 Knots, to 2000 as fast as possible, say to clear the noise restriction zone.

Is it better to let the plane get to some 100 Knots then pull back and climb or just start the climb right away?

As an example practicing full speed stall maneuver I have noticed I climb at a rate of 1500 feet/min while on Vy my rate is never more than 650 feet/min.


texts: What was the first aircraft fitted with both an FDR & CVR?

texts: What was the first production aircraft to be fitted with a Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) as standard by the manufacturer?


texts: Does a glider pilot need to file an IFR flight plan to legally fly in cloud in class E airspace in the US?

texts:
Does a glider pilot need to file an IFR flight plan to legally fly in cloud in class E (controlled) airspace in the US? Or could he or she contact ATC and receive a clearance to enter cloud without actually filing an IFR flight plan?

Assume that the glider pilot has an instrument rating in airplanes (as required by FAR 61.e.3), and the glider has all the equipment required to legally operate in Instrument Meteorological Conditions under Instrument Flight Rules.

Background information-- I know of a case several decades ago where a glider pilot legally thermalled high into a towering cumulus cloud to set a state altitude record under conditions similar to those described above.  The state record would not have been granted if the flight had been conducted in violation of any FARs.  I don't know whether or not an IFR flight plan was actually filed.  Note that FARs 91.619 and 91.153 do contain the phrase "Unless otherwise authorized by ATC" when describing what information must be included on in IFR flight plan, so if an IFR flight plan was filed in this case, it may have looked quite different from a typical one.

Related--

Does a request for a Pop-Up IFR clearance constitute filing a flight plan?

Can you file an open-ended IFR flight plan?

What IFR clearances may a pilot obtain from ATC directly without a pre-filed flight plan with FSS?

What IFR clearances may a pilot obtain from ATC directly without a pre-filed flight plan with FSS?


texts: What are these ribbons on the wing of an MD-83?

texts: What are these triangles and ribbons on this MD83's wing, and what do they do?


texts:
I am considering enrolling in a PPL course, and am getting information about the flight schools in my city (Rome, Italy).

What should I be looking for?
How can I choose among them?
Their fees differ by at least €3000. Are there differences between the schools that justify such different prices?


texts:
The MEL, minimum equipment list, defines whether fault of some equipment on the aircraft prevents it from being dispatched for flight or not.

However, sometimes (e.g. in comments to this question) there is misunderstanding regarding what it means to say something is on the MEL. So, when I say something is on the MEL, does it mean that:

the aircraft can't be dispatched without it, i.e. the list contains the required items, or
that the aircraft can be dispatched without it, i.e. the list contains the optional items?

This answer suggests the former, but I've heard/read it used in the other way, so I would like some clarification.


texts: What are the performance adjustments for a Beechcraft B1900D on a wet runway?

texts:
I am doing runway analysis for B1900D and AFM Section 5, does not provide correction to V1 or the takeoff weight for takeoff on a wet runway.

Appreciate if someone can provide information regarding such correction or the method.


texts: What help do you have to provide if you are seated in the emergency row and there is a situation?

texts:
Follow up from What if there are no volunteers to sit in the emergency exit row? and @mins 's comment:

  I'm curious... What prevents someone to say they will assist and then just rush out of the plane when the need to assist is here? Tons of people are ready to promise anything to get what they want, and then just say they didn't understand what they were asked for (or more likely swear that they were not asked anything... show me the evidence...)

..What are actually your responsibilities in case an actual emergency occurs and you have to do the assisting tasks?


texts: KC-130: What are the four tanks/tube on the wings in between the engines used for?

texts:
On the KC-130, what are the 4 tanks/tube on the wings in between the engines used for?

I've seen them in photos but without explanation. I cannot find any mention of them whatsoever. If not storage tanks then what else would they be used for?


texts: Is this a wing-tip device on the A-10 "Warthog"?

texts:
Source: Flickr courtesy of: U.S. Air Forces Central Public Affairs, photo by Master Sgt. William Greer

Notice at the side edges, the wing peels down and back around towards the fuselage. (The airplane is upside-down in this photo.)

Never noticed this before. Is this a wing-tip device producing more lift? If so, what kind is it? I would like to read more about it.


texts: How common are regulations limiting when the FO can be PF?

texts:
I was reading that in India regulators have specified certain airports at which the FO is not allowed to take off or land.

  The Pilot-in-Command shall not authorise a Co-pilot to effect supervised take-off or landing when TODA/LDA is  marginal. A margin of at least 1000 feet must be ensured.  Critical airfields,  [Mangalore, Port Blair, Leh, Agartala, Lengpui, Shimla & Kullu airports]  are specifically excluded for supervised take off and landing.

As a matter of fact they have several limits in place where 'supervised takeoffs and landings' are not allowed and the PIC must fly the plane.

In this unique to India or are limits on FO's common?


texts: When will the Canadian ADS-B satellite system be implemented?

texts:
It is interesting that ADS-B is not mandated in Canada as of yet. If you fly in the US you quickly realize the benefits. Now as I understand it Nav Canada is the largest shareholder in Iridum but ADS-B in the SDA (Southern Domestic Airspace) is still far off.

Some people may hate the idea of a mandate but I fly in the south and it is crucial to be able to see other traffic. XM is great for WX but expensive. I am curious as to why Nav-can is not hot on the ADS-B trail other than the politics of mandated dollars for Mode-S transponders.

Does anyone know the timing for implementation of the ADS-B satellite system for Canada?


texts: What is this aircraft with wings seemingly fixed the wrong way?

texts:
In this page there is this image:

Is it a concept model or a real model?
If this is the latter, then are there real aircraft with such wings?


texts: Why is tangential velocity a loss of kinetic energy in a turbine section?

texts:
While researching turbine engines I came across a statement

The mass of airflow naturally does not change in the transfer of energy to the rotor system, but the velocity of mass flow being slowed axially is said to account for the energy of flow as the energy of shaft power is increased. In other words, tangential velocity is essentially a loss of kinetic energy to the engine.

Why and how does this the loss occur, and how can this loss be reduced?
I'm not trying to get an in-depth mathematical aspect on that topic as I'm still a beginner with the study of gas turbines, a simpler theoretical non-math explanation would very much be appreciated, thanks!


texts:
As I wrote last week, I'm doing a Benedek 10355 airfoil performance report.
At this point of the work I am analyzing the stall of the profile at a fixed Reynolds number.
The Benedek 10355 airfoil has a thickness of 10.1%.
Figure 1 shows the polar calculated with Xfoil at Reynolds number = 500,000.

Analyzing this curve, and comparing it with this answer, it seems to me that we are in the presence of a trailing edge stall.
In fact, after the stall angle ($\alpha_{stall} = 11.0°$), the decrease in the lift coefficient is gradual ... Then, however, at about $\alpha = 21°$ there is a sudden change in lift, as if a laminar bubble had "burst".
Figure 2 shows the separated zone for $\alpha = \alpha_{stall} = 11.0°$.

Looking at the pressure coefficient, there appears to be a laminar bubble very close to the leading edge (Figure 3).
As the incidence increases, this bubble moves more and more towards the leading edge and, when $\alpha = 22°$, it "disappears".
This makes me think that maybe at low incidences there is a trailing edge stall and then, going further, a leading edge stall ...
Maybe I'm missing something?
Thanks.


texts: What do the pilots do if the plane they are operating does not have an anti-ice system?

texts:
Anti-icing equipment is designed to prevent the formation of ice, while deicing equipment is designed to remove ice once it has formed. These systems protect the leading edge of wing and tail surfaces, pitot and static port openings, fuel tank vents, stall warning devices, windshields, and propeller blades.

.What if the plane does not not have any anti - ice systems
Here is my research about one type of plane that does not have an anti - ice system and what do the pilots do to deice the plane.

A Cessna 172 has no anti icing system, as long as I remember a electrical pitot heater for preventing freezing over the pitot tube and a carb heater for preventing formation of ice in carburetor are the only two ways to prevent ice from forming; for that the C172 cannot fly in icy conditions.

I have researched about this topic and I am still looking forward to learn from the users who answer my question.


texts: How do you win a simulated dogfight/Air-to-Air engagement?

texts:
When simulating/practicing a dogfight/air-to-air engagement obviously real, live weapons aren't used. So therefore, how is it that these missions are "won"?
So my first question is: In a within visual range fight (assuming FOX 2/guns distances) how is the fight won? Is it determined by who can sit on the 6 o'clock of their opponent, or is there a system kind of like laser tag to determine if a gun shot (or missile simulation) lands on target.
And 2: How can you simulate/practice BVR engagements? Is there a way to effectively use a "virtual reality" missile that can simulate if the target is hit, and further to that, do Countermeasures have any relevance in these practice engagements?


texts: How does 'standalone' propeller efficiency change with altitude?

texts:
I've seen questions regarding propeller aircraft and altitude and their interaction. But I'm wondering what the relationship between just the propeller and altitude (changing air density) is. How does the efficiency and ability of a propeller scale with altitude?
Real-life scenario which inspired this question: a two-bladed two-engine propeller system is being used to propel a payload on a balloon platform (i.e lift is handled by helium buoyancy, no minimum speed required to stay afloat). The propeller is only used to move horizontally slowly (< 5m/s). This occurs at 65,000 feet and the propellers were analyzed at these conditions. Now, the new altitude is going to be 85,000 feet. How does that affect the scaling and re-design of the propulsion system? The Reynolds number will of course be different for the same desired airspeed. Additionally, the system drag will be lower so less thrust will be required at the same airspeed. But if the required thrust needed was the same, how does that and other factors affect the efficiency? And knowing that the required thrust will be lower scaled to air density, what is the expected change in propeller requirements?
Addendum: can the same 65,000 feet propellers be used at 85,000 feet, or is a new design required?


texts: Can a 737NG still fly when every single electric run device/system is dead?

texts: So, as my title suggest, I wonder if the 737NG can still fly without any of it's electric run systems, which means anything that runs on electricity is dead.


texts: Which manufacturer produced this fan blade?

texts:
I acquired a fan blade a few years back, but have not had any luck finding out who manufactured it or what engine/aircraft it may have come from.
The only data I can find on the blade is as follows:

4922T12P01
99207 6018730P02
KGA 65444
GR.IN.
15.620

65444 is hand engraved again in larger size above the data listed, which I assume is the serial number. The blade is about 15" from tip to root. I am curious about the root itself, as I have not seen other blades with a mount like this one. If anyone can help out it would be greatly appreciated.

Images can be seen in full size by clicking on them


texts: Would the wings of a Boeing 787 be snapped off in the same turbulence in which a DC-8 lost an engine and parts of a wing?

texts:
From forbes.com:

  In 1992, a DC 8 cargo aircraft suffered turbulence so severe over the Front Range of Colorado’s Rocky Mountains that its left outboard engine was completely ripped off as well as some 12 feet of its left wing’s leading edge. Mercifully, the pilot was able to make an emergency landing at Denver International.

If a 787 was put in the same turbulence as the DC-8, would the wings snap off? The DC-8 is from the '50s while the 787 is a new aircraft.


texts: I understand the need for a trimming mechanism, but why use a secondary control surface placed on top of the first, when you could just adjust the resting position of the aileron/elevator/rudder itself?


texts: How do class E/G airfields charge for stops without refuel?

texts: Do many Class E/G airfields charge for short stops without gas purchase? Sorry for the stupid question...recent PPL here and my training has mostly been T&G rather than full stops to the FBO. Planning a XC to KSHD and wanted to stop in for a bit to check out the facility.


texts:
Excluding how a runway would exist at 30,000 ft, could landing a plane at that altitude be done? What would it take to do so?

Very Basic Wind rose for Mount Everest
Weather Phenomena That Could Impact Aviation Operations:
High Density altitude (1/3) density altitude of sea level. Planes capable of a ceiling of 35000 ft required. Ground effect deceleration landing required.  Strong crosswinds and updrafts present year-round. Build from ice, the runway is 3 to 5 times longer to compensate for Density Altitude, wind, and ice. 10 percent chance of rain year-round. In the middle of June to September the monsoon season produces heavy precipitation. The temperature ranges from -2º F to -76º F. Banner clouds often present. The Subtropical jet stream maybe present with winds exceeding 80mph. If the Polar jet stream merges with the sub-tropical jet stream wind could exceeded 120mph. Supplemental oxygen maybe needed. Presume landing is done in head-wind only.


texts: Why don't helicopter rotors use curved blades? Curved from the top view.

texts: I'm studying blade element analysis and I tried applying it to curved rectangular blades instead of straight ones. It doesn't really show any significant changes in the inflow ratio computation. Why not use curved blades? Is there any reason apart from the obvious problem of increased flapping?


texts: Are there differences in air traffic services between western nations?

texts: What are the major differences (if any) between the air traffic control service in Europe vs. USA vs. Canada?


texts: Is it a common airline practice to base T/O speeds on the actual T/O weight when an assumed temp thrust is used?

texts:
Let's say the current outside air temp is 15 C and you have decided to use 50 C as the today's assumed temperature for your takeoff. In this case, use of the T/O weight the assumed temp thrust supports gives you the balanced V1.

But our company rules are to use the T/O speeds of the "acutual" T/O weight instead of those that the T/O weight the assumed temp thrust applied provides. I assume this rule has been made to give a greater safety margin for a runway overrun in the event of a possible rejected takeoff at the expense of decreased obstacle clearance, since use of the actual takeoff weight invariably brings lower V1, Vr, and V2 speed than when the T/O weight of the assumed temp thrust is used. My question is: is it a common practice among commericial airlines to use the actual T/O weight instead of the assumed temp T/O weight?


texts:
The engine was turned off at 1000m above sea level. If you ignore the landing pattern, how long can the runway be within a few kilometers of the landing to safely land? However, the wind is blowing at 72 km / h from behind.

Empty weight = 90kg, fuel = 30kg
zero lift drag coefficient = 0.05
Oswald = 0.75
Span 4.5 m
Wing w Area 3.7m^2
Cl =0.1(alpha + 1)

I am really confused if the wind is blew from head or tail how it influence on range.


texts: What is the FAA Approval Basis for an FMS upgrade on a Part 25 aircraft?

texts:
Does anyone know of a recent approval for an upgrade from a Universal UNS-xx FMS  to a Universal UNS-1Ew FMS on a FAA registered aircraft, other than a TC, TC update or an STC?

I am looking for the specific guidance which would allow a FAA Principal Inspector to do a Field Approval and/or sign the Flight Manual Supplement approval.


texts: What does RPM mean in a propellor aircraft, compared to a jet aircraft?

texts: What is the practical significance of speed RPM in a propeller aircraft for a pilot? I am not able to correlate it with RPM in jet engines?


texts: Why is the mammatus cloud formation so dangerous?

texts:
I have read and heard that the mammatus cloud formation presents a danger to aircraft and is often associated with funnel clouds and tornadoes. How is it formed and why is it dangerous?

Source: Wikipedia


texts: What type of flow is preferable for jet engines?

texts: I would like to know how laminar/turbulent flow affects engine performance. Any additional thoughts on the topic, even if not strictly related to the main question, are welcomed.


texts: When are the engine bleed air, APU and packs turned on in the B737?

texts: When do I have to turn on the engine bleed air and APU? In videos I have seen that they are always on, and sometimes they turn them off after take-off. I also have the same question about the packs.


texts: Are student pilots required to have spin entry and recovery training?

texts: Do trainee pilots learn to enter into spins and recover from them in any basic trainer aircraft? Does any regulation mandate this?


texts: A Lockheed T-33 crashed near my hometown (Outer Cove, Newfoundland) in 1956. This year we have had some very strong storm surges, and a piece of metal has washed up on the shore. I am posting this picture to see if anyone  can tell if it is part of the crashed T-33. Thanks.


texts: Why simple paper planes fly better than most "realistic" paper plane models?

texts:
Just a A4 paper sheet folded into a plane seems to fly decently. But a model of actual (big) plane made out of paper is only good at falling...

What is different for paper planes? Are there "modern and improved" designs of paper planes?


texts: What's the point of separating the Alternator and Battery switches?

texts: What's the point of having a different button for the battery? Why does the alternator turn on simultaneously with the battery? I need an easy and short explanation, if possible.