texts: How are bags transported from the terminal to the airplane?

texts:
I'm curious how bags are transported from the terminal sortation system to the aircraft. I'm mostly trying to understand the "average tarmac distance" a bag will travel. If anyone has direct insight into that metric that might be even more helpful than understanding the process.
I grabbed a screenshot of the United Terminal at DIA to try to map out how this could be implemented. Can anyone help with insight into which process implementation is generally used in the industry?

Each gate has a "sort point" and bags are transported a short distance from that gate sort point to the plane parked at the gate.

One sort point serves "N" number of gates. One baggage handling Cart serves only one plane. (How big is "N" if this method is used?)

One sort point serves "N" number of gates. One baggage handling Cart may serve several planes, detaching a section of the the train at each craft.

Are any of these methods used? Or perhaps could several sort points feed one aircraft? Does this vary airport-to-airport or airline-to-airline? Who is generally responsible for the design of the process - the airport or the airline? Do ULDs have a different process than each-loaded bags? What about smaller regional jets loaded at the far ends of the terminals - are their sort points further away? How does the process look for offloading bags from the aircraft?


texts: Is there a formula for calculating the pivot point of an aircraft while turning on the ground?

texts:
I'm working on a program that requires a taxiing passenger aircraft (of any model) to perform a semi-accurate turn given a steering angle of the front landing gear. For this I need to calculate the pivot/center point for the aircraft to rotate around. There seem to be a few factors that influence this (including some basic specifications of the aircraft) but I can't seem to find even a general equation that breaks it down.

I'm aware that there are also a number of more complex factors that would influence this, but for my purposes I'm assuming an ideal situation with minimal interference.

Thanks in advance!


texts: Why do I never see fighter jets on sites like FlighRadar24 and ADBSExchange.com

texts: On ADS-B Exchange they even have a filter option for military aircraft, and it will show all kinds of transport, mid-air refuelers, helicopters, and even training aircraft like the Texan, but I don't think I ever see fighter jets on there. Even when I see some F/A-18s fly overhead IRL I still never see them show up on any websites. Or like right now I noticed that Air Force 1 was flying out of Palm Beach I think it was but I didn't see any fighter escorts show up. Are fighters allowed to just turn off their transponders in civilian airspace?


texts: What is this strange structure, of a type often seen by pilots in hilly regions?

texts:
I spotted a strange structure near a few paragliding spots in italian Alps. It's a screen about 10 meters wide, 6 meters tall, mounted on concrete base on ridge top. Someone said it's a training target for fighter jets, is it true? If so, is it targeted with real ammo or some kind of video-based training system?

Pictured: Monte Dolada, 46°11'34.68"N, 12°20'25.41"E


texts:
On a recent passenger flight my son asked me, "How come we're able to build a 737 for \$50M - \$80M with fantastic reliability and technology but can't design a PA system so that we can understand the pilot's announcements?" Many are quite un-intelligible but the cabin crew announcements generally are intelligible. I didn't have a good answer. Does anyone know?

As a follow on and of more concern, if pilots' microphone technique / equipment is so poor then how does air-traffic control understand them? I know there is a limited vocabulary set and that standard phrases are used to avoid mis-hearing but there must be some problems.


texts: Could a commercial plane like Airbus A320 glide with no working engines from 11000 meters?

texts: I have heard that pilots learn in simulators to fly also commercial planes without working engines, so that they glide. And still I have the impression, the chances that a plane could float from 11000 meters height are nearly 0. Could someone explain, if a commercial plain CAN BE THEORETICALLY (Physics) and PRACTICALLY landed from 11km with all failed engines? How important is the altitude from which all engines fail?


texts: How does hovering in ground effect (IGE) reduce drag?

texts:
I understand that when IGE the induced velocity and thus the induced angle is reduced, rotating the total aerodynamic force (TAF) closer to the vertical and hence increasing the vertical component of lift (for the same power).
What I don't understand is why drag is reduced (some texts refer to a reduction in induced drag, others to rotor drag). Diagrammatically, the horizontal component of drag (parallel to the tip path plane and that which opposes rotor RPM) actually appears to increase.
I've concocted this diagram which may itself be incorrect and the source of confusion, or maybe its just semantics?


texts: if temperature is increased but the volume contained in a area, will an air balloon lift?

texts: I understand the archimedes principle as it relates to water, but am having trouble reconciling a thesis related to a hot air balloon.  If theoretically, I could increase the temperature of air contained in a fixed pocket/container, would the increased pressure exerted upward lift the container?  The archimedes principle would argue against the prospect of lifting the container due to the fact that the container remains the same size and therefore displaces the same amount of air outside.  However, I find it difficult to understand why increased upward pressure on the container would not lift the container.  Can you explain?


texts:
My question: Where is V15 and how do I find it?

The question referred to in the practice test:

  Refer to the figure 21, area 2 below: What is the floor of controlled airspace along V15?

The correct answer was 1200 ft AGL.

I want to thank @757toga, and @JScarry for the help on this. I made an 88 on my Drone certification that I took today (10/11/2018)


texts: How hard is it to certify a kit aircraft if it is based on a production design like a Cessna 180?

texts:
I was looking at older planes, specifically the Cessna 180. It is discontinued, but people love them, so they fetch premiums. I saw St. Just Aviation has a kit Cessna 180. There are only 25ish planes in existence.

I'm curious if it would still take a large amount of testing to certify their replicated design - since the Cessna 180 already went through all that years ago?


texts: Aircraft fuselages being shipped on a boat

texts:
Earlier this morning, my wife and I were down by the docks in Southampton (UK), watching cruise-liners move about with our binoculars. Whilst panning around, we noticed two old aircraft bodies (/fuselages - are the terms interchangeable?) on a large trailer, looking like they were waiting to be loaded onto a cargo vessel.

They had the wings, tail & nose removed, but the cavities that this exposes had been covered by yellow maintenance covers. I can't imagine they are simply being scrapped if the innards were protected like this.

So, I imagine they are being shipped somewhere for spares, is this trade a regular thing, and we just don't normally see it?


texts: What are the differences between these IFR Low Altitude Chart Navaid Symbols?

texts:
Below are three NAVAID chart symbols. There is almost no explanation on the aeronautical chart user's guide. It even says that a navaid with an FSS will be shaded but the third box has an FSS and it isn't shaded!

I would like to understand what everything on each of these boxes stands for.


texts: Is there a benefit to a pilot/aviator having an FCC GROL license?

texts:
I am an avionics technician (c-130) in the USAF and plan on learning to fly helicopters when I separate in about a year.

I have debated whether or not to pursue a GROL or possibly A&P.  From what I know, these are generally intended for maintainers/technicians rather than aviators.

That said, would there be any benefit to having a GROL or related license for an aspiring helicopter pilot?


texts: Why does the U-2 use a chase car when landing?

texts: Why does the Lockheed Martin U-2 spy plane need a car behind it during landing? Is that to help the pilot in case of excursion off the runway?


texts: Is it legal for an SEP airplane to fly above its service ceiling?

texts:
Let's take a Cessna 172R for example. According to the POH this airplane has a service ceiling of 13,500 ft.

I know that the service ceiling is the maximum altitude where a 100 foot per minute climb can be maintained.
So that would mean that it can technically continue the climb and fly well above his service ceiling, until full power is required for level flight (Correct me if i'm wrong here).

My question is, besides the physical barrier, is there any regulations that would prevent and aircraft to fly higher than his certified service ceiling?


texts: Can an American citizen schooling abroad join the airforce?

texts:
I am a citizen of the U.S who is studying abroad from the age of 9.
If I am to Apply to become a test pilot will there be any impediments?
Due to security issues as it deals with classified aircrafts.
Aviation is something I really want to get into and I plan on taking aerospace for my college course, becoming a test pilot is an overlap of both worlds and is something I always wanted to be. I feel such reasons could be a hindrance.
Any links and answers will be much appreciated and If this question is not within guidelines a point in the right direction would awesome.


texts: How is the correct air speed for fuel combustion obtained at the inlet of the combustor?

texts:
Many jet aircraft travel at speed of about Mach .8 which at an altitude of 11 km represents an airspeed of about 300 kt or 150 m/s.

If fuel was injected into air at this speed, the mix would just leave the engine before being burnt, combustion would occur behind the aircraft. From different readings, I believe the correct airspeed in the combustor must be around 10 or 20 m/s to maintain the combustion within the combustor.
In the compressor section, air from the intake is forced to rush into a convergent annular tunnel to compress it. Intuitively, this design won't slow air, or not slow it enough.

General Electric J85-GE-17A, source: Wikipedia

How engineers are able to slow air without decompressing it?


texts: How is crankcase ventilation handled in R-2800?

texts: I just finished R-2800: P&W's Dependable Masterpiece and noticed there's no mention of a pump for crankcase ventilation. Is this handled by the oil scavenge pumps?


texts:
All this confusion over flight 370 has me wondering if it would be possible to hack into an airplane and control the autopilot or other on-board systems in a way that the pilots couldn't regain control.

I know some basic searching reveals some articles such as this one. If the plane can't be hacked, could someone with the proper knowledge snip or disable the pilot's override?

Disclaimer: I know 0 about aviation, but I am a programmer. So my guess would be that anything that doesn't have a physical disconnect would be vulnerable to being hacked without being able to override it.

Additional Disclaimer: This is a question about curiousity / possibility, not a how-to.


texts: What is the reason for the T- shaped rudder trim tab on the DA42?

texts: Why does the rudder trim tab on the DA42 have a T-shape?


texts: Does an uncovered naval aircraft suffer any weathering affects?

texts:
This question is for WW2-era naval aircraft.

I noticed that some cruisers and battleships carried a couple seaplanes, launched by catapult and recovered with cranes.

Obviously these are unprotected by a hangar. So it raises the question, is a hangar really necessary to protect naval aircraft from the weather? Naval aircraft should be more stalwart against seawater at the very least, and I can't imagine that freshwater rain would do anything to even a land-based plane. Dirt and sand also seem a remote possibility. Only thing left I can think of is sunlight over long periods.

The question pertains to seaplanes as well as wheeled aircraft, if they are carrier aircraft. (I understand that carriers have a hangar for maintenance and/or an armored roof, but my question is about the need, or not, for weather protection.) Can naval aircraft just be left on the deck without ill-effects?


texts: How much the true altitude will be lower than indicated altitude by 10°C colder?

texts: Aproximately how many perecent the true altitude will be lower than your indicated altitude , if the temperture is 10°C colder than standard ?


texts:
What are the standard stability derivative formulas and typical GA values?

I suppose values for the C172 would be the best benchmark.


texts: What is the stall speed of the Antonov An-225?

texts: Under certain circumstances - maximum gross weight, unaccelerated 1G flight, clean configuration (landing gear up and flaps)? Indicated airspeed (KIAS) of course.


texts: Why is a turbofan engine less efficient when air leaks over fan blade tips?

texts:
Image source

I understand part of the reasoning for minimal clearance between the casing and the fan blades, is to have the larger fan blade possible, which generates a larger low pressure area to increase air intake.

However I don't understand why, if leaking occurred, it would reduce the overall efficiency.

If it was to leak, it's still going through the intake to the compressor or bypass duct.


texts: What happens when a pilot has no Instrument Rating and visibility drops?

texts:
Note: I'm not a pilot, so I don't have much basic knowledge of how the pilot licence ratings work

If a pilot doesn't have an Instrument Rating, and the weather conditions drop below VMC; what do they do?

Presumably you can't instantly land, but nor can you safely continue to fly without sufficient visibility?

I know the basic licence includes some instrument training, but is this enough to fly and land without visibility? I was under the impression that was the entire point of gaining an Instrument Rating... To train the pilot to fly on instruments alone


texts: Why does my Surface Analysis chart indicates radar returns / rain when none exist?

texts:
I'm using 1800wxbrief.com to get all the information necessary to brief myself on an upcoming flight.

I have noticed each time I've done this, that the Surface Analysis chart shows light / spotted rain where I can be nearly positive there is none. When cross checking this chart with sites like weather.com, it is confirmed through their weather products that there is no rain in the area.

Do these Surface Analysis charts sometimes show spotty false positives?


texts:
The KC-46 tanker aircraft (the U.S. military's designation for the 767s it uses as tankers, and which every other country calls the KC-767) uses an early version of an MCAS.1  This was ostensibly developed to cope with shifts in the aircraft's weight and center of mass during aerial-refuelling operations:

  ...  The KC-46 uses a similar system because the weight and balance of the tanker shifts as it redistributes and offloads fuel. The KC-46 has a two-sensor MCAS system, which “compares the two readings,” the Air Force said.

However, even though changes in weight and balance as a result of onloading, transferring, and offloading fuel are common to all tankers, and, yet, the KC-135, KC-10, KC-130, KC-30, et al, do just fine without any MCASesque system.

What makes the KC-46 special in this regard?

1: The KC-46's early-model MCAS was later developed (incompetently) into the MCAS version used on the 737 MAX.


texts: Can wing clouds caused by a high angle of attack be recreated in a lab? Also, why doesn't this work for smaller wings (e.g. r/c planes)

texts: Can this be recreated in a lab? Any equations would be helpful if so. Also, why doesn't this happen during high angles of attack on a smaller wing, such as that of an R/C plane?


texts: How should the pressure coefficient distribution from a wind tunnel experiment be interpreted?

texts:
I'm doing a wind tunnel experiment and I'm trying to plot the pressure coefficient distribution for the upper and the lower surfaces of an airfoil based on experimental data. The airfoil chord is 150 mm.

I have the pressure static ports located at:

Upper static port #: 1    3    5     7     9     11    13    15     17     19
X-coord [mm]:        0.76 3.81 11.43 19.05 38.00 62.00 80.77 101.35 121.92 137.16

Lower static port #: 2    4    6     8     10    12    14    16    18     20
X-coord [mm]:        1.52 7.62 15.24 22.86 41.15 59.44 77.73 96.02 114.30 129.54

And the pressure readings for each static port are the following:

Static port #:     1      2      3      4      5      6      7      8      9     10    11     12     13    14     15     16    17   18     19     20
Pressure [kPa]:   -0.034 -0.113 -0.087 -0.172 -0.136 -0.168 -0.148 -0.17 -0.15 -0.156 -0.133 -0.15 -0.124 -0.139 -0.12 -0.13 -0.13 -0.13 -0.117 -0.12

I also have Pitot velocity reading: $U_\infty=12.26$ m/s, density: $\rho=1.225$ kg/$m^3$ and $p_\infty=101.3$ kPa.

I know that to compute the pressure coefficient for each static port, I have to use:
$$c_p(x,z(x)) = \dfrac{p(x,z(x))-p_\infty}{1/2\cdot \rho_\infty \cdot U_\infty^2 }$$

I coded a MATLAB script that allows me to compute this equation for the upper part of the airfoil using the odd static ports readings, and for the lower part of the airfoil by using the even static ports readings of pressure.

But I'm having two problems that are a bit strange,

Pressure coefficient must be dimensionless. I have the pressure values in "kPa" and the problem is that if I convert them into "Pa" by multiplying a 1000 factor. The pressure coefficients values will not be around 1, which is what I'm used to seeing in the Cp-chord graphs. How can I fix this? I'm not sure it's correct to use a dividing 1000 factor to compensate this effect.
When I plot the the result I obtain the following result, which is not very similar to the typical Cp-chord plots I have seen in experiments. Am I doing something wrong? Or is it a problem of the experiment in which I obtained bad data?

Could you help me solve my doubts by giving me a little help based on your experience? I'm not asking to get the problem solved, I just want to know how to do it properly.


texts: Why is this plane circling around the Lucknow airport every day?

texts:
Saw this plane circling around Lucknow airport (LKO).
This is happening every day. Any idea what is happening?


texts: Are airport emergency vehicles' sirens louder than normal?

texts:
So there I was this afternoon, sitting in my car waiting on my wife's flight to get in to Dulles Airport (IAD), in the cell phone parking lot. I was listening to some music on the radio when the rescue vehicle (ambulance) got a call to go somewhere. I know this, because it absolutely deafened me. Turns out (one of) the firehouse is right next to the lot. I've been in front of firehouses before when trucks have gotten calls and they weren't THAT loud.

This started me wondering if airport emergency vehicles have extra-loud sirens, due to the greater than normal ambient noise on an airport?


texts: How does Garmin Autoland for General Aviation aircraft work?

texts:
Garmin recently unveiled a new technology for their G3000 General Aviation avionics system, the Garmin Autoland. They claim it can safely and fully autonomously land the aircraft in case of pilot incapacitation.

Traditional autoland systems found on airliners use Cat. II or III Instrument Landing System (ILS) approaches to guide the aircraft onto the runway (and keep it on the centerline afterwards). But according to this article Garmin will not use ILS, but rely on GPS approaches only:

  [t]he availability of a GPS approach with lateral and vertical guidance to the runway is also required when the system is considering various airports and runways.

Can GPS alone provide accurate enough guidance all the way to the runway including the flare? Usually RNAV approaches have higher LPV minima than even a Cat. I ILS.

As far as I know, the autopilot also cannot control systems like the landing gear, the flaps and the brakes, but all are needed for a fully autonomous landing. How does the Garmin system handle this?


texts: Why are pitot-static measurements preferred over other velocimetry techniques?

texts:
I believe hot wire anemometers (HWA, frequently used in wind tunnels to measure flow velocity) or other sensitive techniques could be used to determine the airspeed. Are there specific reasons for why the aircraft industry continues to use pitot-static instruments? Or is it just tradition?
A nice link on HWA's: The hot wire anemometer


texts: When can I log PIC time in a new category of aircraft?

texts:
I am currently a Private Pilot Rotorcraft and I am doing an addon for ASEL. When can I log PIC time?

I've been told it's only when you're the solo occupant but after some reading I'm not so sure. 14 CFR 61.63(d.2) says:

  Have received training required by this part that is appropriate to
  the pilot certification level, aircraft category, class, and type
  rating (if a class or type rating is required) for the aircraft to be
  flown, and have received an endorsement for solo flight in that
  aircraft from an authorized instructor.

Do you have to have your license in category to log pic time? Or is it after you have received your instructor's endorsement to fly solo per 61.63?

When I showed this to my instructor and we did the endorsement in my logbook we received some backlash from the flight school saying that PIC time is only accrued after you have your PPL in the applicable category of aircraft. During my flight lessons I was always operating the aircraft for the entire duration of the flight after I had received my solo endorsement which satisfies the requirements for PIC time per 61.51(e.IV).

Am I misinterpreting the rules? Can someone point out to me why I wouldn't be able to log PIC time even though it's in a different Category? Thanks for the input!


texts: Can a drone travel beyond the range of its remote control signal?

texts:
In a hobby drone, is it possible to set up the autopilot so that the drone travels to a distance far beyond the range of the remote control device and then comes back to the starting point? When I see hobbyists flying drones , it seems the drone always hovers within the boundaries of the field.

Is it possible for a drone to reach a friend's house on the other side of town and then come back to the start point?


texts: Can propeller driven aircraft sustain speeds at or above Mach 1?

texts: Has any propeller driven aircraft ever achieved and sustained supersonic speed? If not, why can't propeller airplanes achieve that speed?


texts: How much drag does the wings of a Winged EVTOLs like Lilium produces while take-off?

texts: I looked into several questions related to liliums design, and it is confirmed the wings of lilium produces drag during take-off but i just don't know how to calculate the drag produced due to the shape of the wing. What is shape of streamline in this design during take-off and what is the drag experienced by these wings? Can someone help me with a detailed calculation of the drag and power loss due to such structure during take-off alone!


texts: What risks come from passengers taking baggage during emergency evacuation?

texts:
In recent news, the pilot of an aircraft that caught fire was chastising passengers for taking their luggage.

What are the major concerns behind his criticism?

I like to put this in context:

All passengers and crew survived.
There were no injuries.
Crew reported that the evacuation was very orderly and efficient.

So what could be the reason for the pilot speaking out so critically? So critical, in fact, that he argues that overhead-compartment doors should lock between takeoff and landing. My guesses include:

another passenger cohort could have been less orderly, and pushing with luggage resulted in injuries or people becoming trapped.
sliding down inflatable exit slides with luggage could cause the slides to puncture and trap other passengers.
the inflatable exit slides are not rates to carry the weight of an adult + luggage (seems unlikely unless the adult is massively obese).

Would appreciate hearing a list that is not just educated guessing.


texts: Why does the V-22 Osprey have twin stabilizers?

texts:
I've noticed that the Bell Boeing V-22 Osprey has a twin vertical stabilizer, while the AugustaWestland AW609 has a T-Tail.

Bell Boeing V-22 Osprey with twin stabilizers. Credit: Boeing

AW 609 (T-Tail) Credit: Airliners.net

I understand why it was used for fast jet fighters, but why was it used for the V-22? What are the advantages?


texts: Which frequencies does VDL Mode 2 use when used via the ATN (rather than ACARS)?

texts:
If I understand the slide below correctly (source), CPDLC can be used either via ACARS or via ATN.

I know that, in the case of VDL Mode 2, there are specific ACARS frequencies. Which frequencies are used when CPDLC runs over ATN?


texts: Why is Tromsø Airport's runway 01 referred to as 36 in the sign before the runway?

texts: Runway designations can change due to the changing direction of the magnetic north. Using Google Earth, we can verify that Tromsø Airport's runway 01 has not changed its designation since at least 2005. Nevertheless, as we can see at the start of this video the sign just before the runway refers to the runway as runway 36. Does the 36 on the sign refer to the true direction while the number painted on the runway is the compass direction?


texts: How do ATC radars know where to position a primary target?

texts:
Primary target: An aircraft not reporting mode-C, the only thing the controller has is the return on the radar.

When a controller reports a primary target as traffic to other aircraft, the controller does not have the altitude of the target. Given this, I conclude that ATC radar does not have the altitude (angle-up) to the target, and only provides azimuth.

So then without the altitude, how does the radar-system know where to put the target laterally on the screen?

Example, a radar picks up a target that is 10 miles from the station. If the target is 0 AGL, the proper position would be 10 miles out. However, if the target is at 15,000ft, the proper position would be 9.5 miles out.

Since the difference is so small, does the radar just put the target at 10 miles, and the FAA separation guidelines factor in the discrepancy?


texts: Does air travel in the same time over the top of the airfoil and along the bottom?

texts: If we assume two particles of air arriving at the leading edge, one flowing over the airfoil, the other under the airfoil. Do they arrive at trailing edge at exactly the same time?


texts:
When arriving at a busy airport, airliners may be stacked in holding patterns, increasing flight time. I know airliners are required to carry extra fuel in case of rerouting (including a safety margin).

Once in holding pattern, aircraft may be reordered (not as simple as a FIFO), thus some aircraft may stay longer in their holding pattern.

Is there a legal maximum time an aircraft can stay in an holding pattern? If needed, the question may be narrowed to EASA and FAA regulations.


texts: Is a VFR flight following request implied when talking to tower and advising them of your intended airport?

texts:
If I am at a towered airport in class delta airspace and I'm departing VFR and tell the ground where I want to go, is it implied to the controller that I'm requesting VFR flight following?

Let's say I'm at the Chandler Municipal airport (KCHD), and I'm headed to the Scottsdale airport, which is in another class delta, and I probably need to transit the Phoenix bravo airspace.

I call Chandler Tower up and say:

"Skyhawk 283JS with information sierra, FBO, north departure to Scottsdale airport"

Will the tower controller coordinate flight following for me and assign a squawk based on this request? Or do I need to specifically request "VFR flight following" if I want it?


texts: How to understand the requirements for IFR currency?

texts:
So the requirement reads "six instrument approaches;
Holding procedures; and
Intercepting and tracking courses through the use of navigation systems."

I am still a little unclear on how to interpret that statement. I have been told you need to have a combination of the above that equal 6, but you could also read that as you need 6 approaches, 6 holds, 6 Intercepting and Tracking through Navigation Systems. Can someone help explain what I am missing from that rule?


texts: What happens when more than one agency investigates a plane crash?

texts:
Does one accident report overrule the other or would there be two possible outcomes for the disaster?

Some examples

EgyptAir Flight 990 had the NTSB and the ECAA investigate and produced two different reports.

SilkAir Flight 185 had the NTSB and the NTSC investigate and also produced two different reports.


texts: What does aerodynamic noise of an airliner sound like in landing configuration?

texts:
I want to know what aerodynamic noise an airliner makes when flying with both engines shut down. Specifically, it is the sound made by air passing a plane which is in landing configuration, with gear and flaps extended, at a normal approach speed.

I know that it makes a loud noise especially during landing, but normally we cannot distinguish it from the engine sound.


texts: Is it better to have the engines center or apart on a plane?

texts:
Are there any advantages or disadvantages to having the engines closer or farther to the center of the plane?

How is the ideal engine spacing determined length or span wise for performance?

Related: How is the center of mass controlled in planes with multiple tail engines?


texts: How can I design and build an aeroplane from scratch?

texts:
Let's say I want to build an aeroplane completely from scratch (not downloading some blueprints on the internet, I mean really designing it myself). The goal is to create a flyable aeroplane from scratch, that can safely fly.

What would I have to take into consideration and where are good resources for it? I don't want to depend on a wrong formula, and have the wing break off the aeroplane in mid-flight, because there was an error in the equation. So what resources are free (or cheap) and trustworthy?

I know, that the aeroplane should be reasonably aerodynamic and the wings should create lift. How do you test it, when you don't have a wind tunnel?

How can you compute the necessary wingspan and wing area and how do you test and analyze your design? They don't have to be that big, as you can see with the "jetman", who has a relatively small wing strapped to his back.

What programs would you use to run simulations? Are there free alternatives, that could be used instead and are they any good?

The design phase shouldn't cost much, except time. However, if there have to be certain precautions taken that cost something, that's OK.

What materials should be used (fiberglass, wood, carbon fiber, metal)?

How do I get the proof of airworthiness (on a design)? After this is done, I might actually go and build it myself.


texts:
My question stems from the fact that, although this is a very fierce looking, and formidable aircraft with a very powerful engine, Ka-52 Alligator has not seen many export success. Its export is very limited as only Egypt uses this type of helicopters as a foreign customer.

Are there disadvantages of coaxial rotor on attack helicopters?


texts: How do pilots manage to keep aircraft on centerline during taxi?

texts:
Cockpits usually seem to have windows that are high up and it doesn't seem from pictures that they would allow a pilot to look down so easily while sitting in their seat. Please correct me if that is wrong because that is the basic assumption of this question.

Then how do pilots know where the centerline is on the taxiway and runway? They always seem to taxi with nose wheel almost always on that line even when turning. Are there some instruments that help them? Or its the same logic as in a car as to how you find out where the lines are?


texts: What's the difference between ATIS and D-ATIS?

texts: What's the difference between the two? Do you need a special digital VHF radio to receive D-ATIS broadcasts?


texts:
The resources explains that SWEN is the start for Snowtam. (Ref: Snowtam help ) But many snowtams I found starts with SWES which I could not find anything about. What is the difference? Can it have other values? Does snowtam always need to start with one of them?

Example Snowtam from Pilotweb

SWES0701 ESSB 12270841
(SNOWTAM 0701
A) ESSB
B) 12270841 C) 12 F) 4/4/4 G) 1/1/1 H) 5/5/5
N) G1 R S T Y Y1 Y2 Y3
Y4 Y5 YU YW/4/GOOD
R) 1 2 3 4 6 7 EAST NORTH/4/MEDIUM
T) RWY 12 BA 60/48/41. RWY 12 COVER 100 PERCENT. APRON SANDED. ICE
PATCHES ON APRON.)


texts: How long does it take for a regular size airliner jet engine to be warm?

texts: How long does it take from starting of turbine or turbofan or turboprop, either by using an APU or other methods, until the engine is warm enough for safely extracting full power for takeoff?


texts: For an airport to be designated as an IFR alternate, does it have to have a TAF?

texts: For an airport to be designated as an IFR alternate, does it have to have a terminal aerodrome forecast at the alternate airport to confirm that the forecast 600-2 and 800-2 will be in place at the time of arrival?


texts: How quickly could a commercial airline integrate advances in technology into its fleet?

texts:
How quickly would a commercial airline be able to integrate significant advances in technology into its fleet?

Specifically I am interested in large commercial airlines and advances in technology that would substantially increase the efficiency of fuel consumption in passenger aircraft, but I don't have enough of a background in commercial aviation to make an educated guess and have not been able to find a comparable historical example. If someone could provide me with either it would be much appreciated.


texts: Is an aeroplane's design only functional?

texts:
Many parts of a car are not obligatory. They are attached or formed to make the car look better.

Are aeroplanes(especially airliners) only designed for function or are there any parts that are purely for aestethical reasons (On the outside of course)?


texts: What is acceptable visual cue at Decision Height when performing CAT II approach?

texts: For CAT II approach, the decision height is below 200ft but not lower than 100ft with RVR of 300m. In this case, if the aircraft is at 100ft above the ground, should the captain of that aircraft be able to see the runway threshold lights (green) at that moment? Or seeing the approach lights is considered sufficient to continue?


texts: What examples are there of top-mounted engine motor gliders?

texts:
I would like to know which motor gliders are there with regards to the following criteria:

Top-mounted engine
stowable landing gear
great L/D ratio
high maximum g-load
at least 180kg usable weight?

I know of Pipistrel Taurus, but are there any other examples out there with a good glide ratio (Taurus has 41:1 L/D, and 5.33 g-limit)?


texts: Why doesn't Concorde stall when passing Mach 1, where a normal airliner does?

texts:
As Jay Carr asked: What is a high speed stall?, Jan Hudec explained:

  A difference from normal stall is that after supersonic flow separation the lift remains proportional to angle of attack and so the aircraft continues to behave more or less normally except for the change in trim.

This has leaded me to a question: Why doesn't Concorde stall?


texts: 61.129 (a)(3)(v), can it be with multiple instructors?

texts: My question is can the 3 hours in prep for the check ride be done with different instructors, or does it have to be all 3 hours with the same instructor? Thanks.


texts: If you make up your own IFR waypoints, how does ATC know where they are?

texts:
If you make your own IFR waypoints, how does ATC know where they are?

Just finished my IFR course in Canada.

Was surprised to learn that you can make up
your own IFR waypoints.

If all IFR flights must register a flightplan, how does ATC know where your waypoints are if you make them up yourself, or do waypoints need to be registered first?

My flying club has their own IFR waypoints and I heard that some of the fly in fishing camps have their own IFR waypoints.


texts: Can airflow reverse over the flight surfaces of a uav in high wind conditions

texts: Can airflow reverse over the wing of a uav in high tail winds and low forward airspeed i.e 25knt fwd airspeed in a 35 knt tailwind? What would be the overall effect on the elevator and rudder? I suspect the rudder would be remain the same but operate at a reduced efficiency however, wouldn't the function of the elevator reverse and/or become ineffective, especially at high angles of attack? As a point of note, this uav does not have ailerons, I believe the roll effect is achieved as a combination of pitch and yaw.


texts: Why does the Pratt & Whitney 747 have an extra engine on the right side but not left side?

texts: What’s the purpose of this design, and why only on one side?


texts: How do I choose the correct NACA airfoil for my requirements?

texts:
How do you find the correct NACA airfoil to use when you already know the requirements?

All of the research I have done on this has shown how to determine what kind of camber/chord/aspect ratio etc. only, but not how to actually pick the proper NACA airfoil. I would like to know if there is some website or program where you can easily find the correct airfoil given different circumstances. Then I would be more sure of having the correct airfoil when performing my tests. I understand I could just eyeball it, but I would like to be able to find the exact lift that my wings would produce, and that would only come from knowing the exact NACA airfoil.

It doesn't necessarily have to be a NACA airfoil, but it should be some type of airfoil where data can be taken from it.

I also could be approaching this from the wrong way, as I do not have an experienced mentor, so if using NACA is unnecessary or outdated please let me know because I really am at a loss of how to select the proper airfoil.


texts: Are the same units used for stations and waterlines?

texts:
I'm trying to decrypt a US aircraft manufacturer's plan. Could W.L. (waterline) and Sta. (station) references use different units?

For example, I have different distances from W.L. 0 to W.L. 200 and from fuselage Sta.3000 to Sta.3200. Are these references always in inches?


texts: What is the definition of "geometric pitch angle" for a propeller?

texts: My question is regarding the geometric pitch angle of a propeller. Is it the angle between the rotational/propeller plane and the zero lift line of the particular airfoil at a propeller section? Or is it between the propeller plane and the chord line of the airfoil?


texts: Are 'climb via a SID' instructions actually used in the US?

texts:
In the USA, a departing aircraft is instructed to climb:

to flight level and maintain, or
via standard instrument departure (SID)

That's according to US Aeronautical Information Publication (AIP). But pilots say they never hear climb via SID. Can anybody clarify if climb via SID instruction is really used by ATC?


texts: Was this Gulfstream way below the glideslope?

texts:
I saw this YouTube video about a Gulfstream jet that came into landing on Princess Juliana International airport and the landing does not seem to be by the book at all. It seems like the landing gear is only a few centimeters from hitting the fence and a meter from hitting the people on the beach. It looks like to me that he is way below the glideslope, but since I'm not that familiar with Princess Juliana I really can't confirm anything.

Is there any more information available about this incident? Was it actually a normal landing, or was it caused by wind shear or pilot error? How often does this occur?

UPDATE:

I found this comment in the comment section from someone who claim to be a long time pilot:

  Juliana is Class D so 91.129 and 703 applies:

  FAR 91.129 (E) "An airplane approaching to land on a runway served by
  a visual approach slope indicator shall maintain an altitude at
  or above the glide slope until a lower altitude is necessary for a
  safe landing."
  See also FAR 91.703 (a)(1) "Each person operating a civil aircraft of U.S. registry outside of the United States shall: when over the
  high seas, comply with annex 2 (Rules of the Air) to the Convention
  on International Civil Aviation and with 91.117(c), 91.127,
  91.129, and 91.131;

  They were way below the visual glide slope indicators i.e PAPIs (for Juliana), and (from flying this approach myself) it's not necessary for a safe landing. Besides ...it's just not very good practice.

  Sincerely, Long time pilot. (:

I have to say that by my logic thinking: I agree with this guy. I am not a pilot myself, but here is why I agree with him:

Low approach method:
If the plane hits the fence: It could cause the gear to break of (And maybe hit someone) and when the plane touches down on the runway with broken landing gear at flying speed: It could cause a rapture in the fuel tanks, igniting it. And you are essentially a tumbling fireball down the runway.

High approach method:
If you fly higher to avoid the fence: The chances of hitting it and cause a tumbling fireball are greatly lowered. However: You may overrun the runway. But this would be preferred (In my book atleast). Since the plane has touched down on the runway and slowed down: You decrease the chances of fuel ignition when you overrun. And if the fuel ignites at the end: You will most likely end up with the fish. And the fire may not be put out completely, but greatly suppressed. And since the speed also is lowered: The chances of survival is greatly improved.

This is just my personal look on this. And some may or may not agree with me. But since the YouTube comment is there: I though there might be something to this.


texts: Why are emergency-instructions by cabin crew like "heads down!" not given via PA?

texts: I just saw a YouTube video of a landing airliner with the gear not fully extended and the cabin crew gave the instructions "Stay down! Heads down!" repeatedly to passengers but without any technical help like PA. Why is that the case? Why don't they use the PA system for commands like that?


texts: What ISA temperature to use in the density altitude calculation?

texts: In the density altitude formula: DA = PA + [120 x (OAT - ISA Temp.)], should one use the ISA temperature at the field elevation or the ISA temperature at the pressure altitude?


texts: Is it possible and effective to perform a forward slip in a large commercial jet?

texts: I'm wondering if it's possible to forward slip a large commercial aircraft, like the A320 or even B777, and if so:  is effective or useful, since most small aircraft which I gather do it have no spoilers for instance which large aircraft do?


texts: What is the A350's procedure for stained cockpit windows?

texts:
Recently I read of this Ethiopian B737 incident at Dire Dawa on Jan 9th 2020. The aircraft flew through a swarm of locusts, which didn't cause any significant damage, but it rendered the cockpit windows completely opaque. So it clearly can happen.

Now on most aircraft, including B737 from that incident, the cockpit side windows can be opened and provide enough forward visibility to land the airplane from basically any available instrument approach.

However, A350 does not have any opening window that could be used, and Cat IIIB approaches that can be executed without any visibility are much rarer than just any instrument approach, so none may be available in range.

So what would the pilots do?


texts: Why does TCAS not issue turning commands as Resolution Advisory?

texts:
The TCAS (Traffic Collision Avoidance System) is capable of issuing RA (Resolution Advisory) when a mid-air collision is imminent by telling the pilots to "climb", "descend", "increase climb" etc.

Why does the system only issues commands in the vertical direction, but not the horizontal direction? It seems an oversight in the design of the system to not make use of all available maneuver options to resolve a traffic conflict. Why can't the system tell the pilots to "turn left", "increase right turn" etc.?


texts: What is the minimum allowed altitude for helicopters over a residential area in the US?

texts:
I observed a helicopter hovering over a residential area/houses for more than 20-30 minutes. I would guesstimate about 500 feet altitude or more for the helicopter. The low altitude and long duration of the hovering created lots of what I would call unpleasant "noise pollution".

What is the FAA minimum allowed altitude for helicopters over a residential area?

re "possible duplicate":

@fooot I already googled and read that entire question. That question is asking about "when is a Helicopter legally allowed by FAA to fly below the FAA's minimum allowed safe altitude?" and that question is even more specific to a specific situation observed by the OP. They both have wording that talks about minimum altitude but are not the same question.

As others have noted in the comments, they agree this is not a duplicate.


texts: Has there ever been a seaplane with retractable pontoons?

texts:
I would like to know if there's ever been a seaplane in which all of its pontoons or sponsoons are retractable after takeoff.

This could be a seaplane with 1 or 2 main pontoons that somehow retract. Or more likely, this could be a flying boat (bouyant hull) whose under-wing pontoons retract into the wing. I will also count a flying boat with only sponsoons that can retract somehow.


texts: What was the normal flight path for a passenger aircraft from New York to Miami in 1955?

texts: What was the normal flight path a passenger aircraft would have flown from New York to Miami in 1955? Like Pan American, flight 914.


texts: What is the chime that can be heard roughly 30 seconds after takeoff?

texts:
This may be confirmation bias on my part, this might be impatient passengers pressing the call button, and it might be me imagining things, but it's one of those I've wondered about. I'll try to describe as best I can.

Of all the times I've flown recently on an airliner, of which most of the time it's a short haul carrier often flying smaller Boeing/Airbus aircraft*, I have been aware that there is an audible chime which can be heard throughout the cabin (ie, not only when sat in the vicinity of crew seats) very soon (30-45 seconds) after take-off.

It is heard well before the passenger seat-belt signs are switched off.

Can anyone describe what I am hearing and what its purpose is? Who is this a signal for, and who is sending the signal?

* the two times I've flown on an Embraer I don't recall hearing it


texts: What high-lift devices are used on the Bombardier Dash 8 Q400?

texts: What type of flaps, slats or other high-lift devices are used on this aircraft?


texts: When filing a VFR Flight Plan, where/how do you include intent to use a Class B transition?

texts:
When intending to use a VFR transition route through Class B airspace, do you put the intended route on the flight plan, the alternate route (if you don't get clearance for some reason), or both?
Which fields does the information go in? e.g. Does the intended route go in route of flight and the alternate in "Other Information" or vice versa?
Example:
I am planning to fly from KHAF to KAPC. Ideally, I'd like to fly using the Bay Shore Transition, as marked on the SFO TAC:

KHAF VPSCS VPOYS VPSBT KAPC

If I'm not cleared into the Class B, I'd instead fly

KHAF SAU KAPC (staying outside the Class B)

How would I file this plan?
Where does one request a VFR transition route through class B? deals with the ATC, not the filing.

Here is the form I will be using:


texts: What could cause a lower manifold pressure at full power after an annual?

texts: I recently completed the annual on my E33 Bonanza.  I notice on takeoff at full power that the MAP is about 1" less pressure than it was in the past at my home airport.  It is also about 1.5" less than ambient.  I notice less power slower Acceleration and lower climb rates.  Fuel flow looks normal.  Where else should I search and troubleshoot?


texts:
How does bypass air exiting the bypass nozzle produce thrust in a turbofan engine?

I thought that thrust was produced by air reacting with the fans. So if thrust happens when there is an action-reaction pair with the air and fan blades, is there additional thrust provided when the mass of air pushed back by the fan blades exits the back of the engine?


texts: What makes airplanes pitch up during landing?

texts: So what exactly pitches the plane upward with the rear end down? Do flaps help lower the nose when deployed 80%-100% down with such low speeds?


texts: Does drag increase with increasing bypass ratio in turbofan engines?

texts: Does drag increase as the bypass ratio increases in turbofan engines? Is there an analytical expression describing the increase in drag related to an increase in the fan duct diameter? How else might one consider this effect?


texts: Steep turn: do we need rudder once we rolled into a bank angle?

texts:
Say a Cessna 172 is in a cruise level flight and clearing turn is just finished. I barely feel a left-turning tendency during the level flight (Maybe torque and slipstream are less significant).
I understand that we should use the rudder simultaneously when rolling into a bank attitude (45 degrees-ish) and then add more power + apply back pressure on the elevator.
But once we've entered into a bank, do we still step on the rudder to stay coordinated? For example, I'm making a left steep turn. After I've rolled into a bank attitude and start turning, do I still need to step on the left rudder?


texts: What would happen to a flying aeroplane if there's suddenly a brick-size hailstorm?

texts:
What would happen to a flying aeroplane if suddenly there is hail in the sky?

For example, ice the size of a brick.


texts: Despite the lessons from DC-10 planes in 70s, why didn't Boeing ensure their cargo doors didn't fail even until the end of the 80s?

texts:
In the early 70s, DC-10 planes had disastrous failures with cargo doors. It proved how massive a havoc faulty cargo doors can have on the planes. Despite those two incidents with Boeing 747 planes in the 80s prove that Boeing were not careful enough to avoid problem with the cargo doors. In fact, there is a striking similarity with what happened to DC planes in 1972(a warning) and in 1974(not learned from the warning) and what happened to Boeing 747 in 1985(warning) and in 1987(not learned from warning).

Why didn't Boeing learn from what happened to DC-10 planes?


texts: Are there non-economic barriers to a 1000 passenger aircraft?

texts:
I know the number 1000 is just an arbitrary number that happens to have some zeros in it, but is there any non-economic obstacle to making a 1000 passenger aircraft?

Also, assume normal-ish space-per-passenger constraints, so 1087 people on a 747 isn't really a 1000-passenger aircraft.


texts:
Thrust-Reverser-Systems

According to various sources, Thrust-Reverser-Systems can be classified as follows ( see e.g. Bräunling's "Flugzeugtriebwerke", Rick's "Gasturbinen und Flugantriebe", Purdue AAE Propulsion's "Thrust Reversing", Aviation StackExchange Questions 1, 2, 3, 4, 5 and 6 ):

Beta Range Propeller
Alternative names: Beta Mode Propeller, Beta Operation Propeller

Engine Type(s): Piston-Prop or Turboprop with a Controllable-Pitch Propeller (CPP) / Variable-Pitch Propeller
Mode of Operation: The pitch of the propeller blades is changed such that the propeller pushes air forward instead of backward.
Specific Example: Allison T56-A-15 on Lockheed C-130H Hercules

Bucket Type Reverser
Alternative names: Bucket Door Reverser, Target (Type) System with External (Type) Doors, Clamshell Door Reverser, Post-Exit Thrust Reverser

Engine Type(s): Turbojet or Low-Bypass Turbofan or Mixed-Flow High-Bypass Turbofan
Controlling Mechanism: Hydraulic
Mode of Operation: Bucket-shaped doors are closed after the engine nozzle. These deflector doors redirect the exhaust air to flow towards the front of the airplane.
Specific Example: Rolls-Royce Tay 620-15 on a Fokker 70

Clamshell Door Reverser
Alternative names: Deflector Door Reverser, Pre-Exit Thrust Reverser

Engine Type(s): Turbojet or Low-Bypass Turbofan or Mixed-Flow High-Bypass Turbofan
Controlling Mechanism: Pneumatic
Mode of Operation: Similar to the Bucket Type Reverser. Distinction: The deflector doors are deployed before the engine nozzle (but after the last turbine stage).
Specific Example: BMW/Rolls-Royce BR710 on a Gulfstream Aerospace G-V Gulfstream V

Cold Stream Reverser

Cold Stream Cascade Reverser

Engine Type(s): High-Bypass Turbofan
Mode of Operation: The rear part of the nacelle (nacelle sleeve) slides back,

which activates the Cascades (guide vanes) to redirect the (outer/secondary) bypass air to flow towards the front of the airplane and
which pivots Blocker Doors to block the (outer/secondary) bypass air just after the Cascades so that the air cannot follow its usual flow direction.

Specific Example: Rolls-Royce Trent 800 Series on a Boeing 777

Cold Stream Pivoting Doors Reverser

Engine Type(s): High-Bypass Turbofan
Mode of Operation: The Pivoting Doors both to redirect the (outer/secondary) bypass air to flow towards the front of the airplane and block the usual flow path.
Specific Example: CFM International CFM56-5C2/4 on an Airbus A340

Question

Which Thrust-Reverser-Systems are used by which engines and aircraft?
So far, I just used standard search engines (web and image) and the Airliners.net Photo Search, but here you have to trust the photographers that they correctly identified the aircraft and engine.
Is there maybe an (official) list that provides the thrust-reverser-system for engine-aircraft-combinations?
If no one has published data sheets with specific engines and the corresponding thrust-reverser-systems and of there is no databases which can be queried for the used thrust-reverser-system of a specific engine, I will accept such an answer.

Note: Feel free to extend the above information and/or turn it into a wiki.


texts: "Report a 3 mile right base" - where is it measured from?

texts: At which position should you report to ATC?


texts: May a helicopter fly at night with only strobe lights?

texts:
I thought that all aircraft flying at night needed red/green/white position lights and red/white anti collision flashing beacons.

I observed a helicopter flying over houses with only its strobe lights. Is that allowed?


texts: Helicopters with landing skids, no wheels; How are they taken in and out of a hangar?

texts:
I'm sure many helicopters also need/use Hangars frequently. How do you take them to a hangar and take them out of it without wheels?

Specially when they have to be taken indoors for some maintenance work on them. Are there any special forklifts/carts used for ground handling of helicopters that do not use wheels and need to be moved without actually flying?


texts: What aircraft could make non-stop transatlantic flights in 1958?

texts:
According to Wikipedia:

  TWA flew to Europe nonstop from O'Hare starting in 1958

The Great Circle Route distance from ORD/KORD to LHR/EGLL is 3953 miles. Other major European airports would have been farther away.

What aircraft were capable of making that non-stop flight in 1958 (also, how long would it have taken)?


texts: Is there an upper age limit for pilots freight only?

texts:
When I asked my original question below, I should have been more specific. I will rephrase my question, however, I do wish to extend my thanks & appreciation to those who answered my question as previously written!

PLEASE ADVISE WHETHER THERE IS AN UPPER AGE LIMIT FOR PILOTS FLYING STRICTLY AIR FREIGHT AND/OR FOR COMPANIES LIKE fEDEX, UPS, DHL, ETC. THAT FLY A MIX OF AIR FREIGHT, DOCUMENTATION, ETC. FLYING ON AMERICAN (USA) FLAG CARRIERS WITHIN THE USA? AND, WHETHER IT MAKES A DIFFERENCE IF THE SAME USA CARRIER FLIES OUT OF THE USA TO ANOTHER COUNTRY SUCH AS CANADA, MEXICO, CENTRAL AMERICA, SOUTH AMERICA, EUROPE, ASIA, AFRICA, ETC.?  DOES THE US POSTAL SERVICE ITS OWN FLEET OF AIRCRAFT, AND, IF SO, DOES IT HAVE AN UPPER AGE LIMIT FOR FLYING US MAIL AND/OR PARCELS?  THANK YOU!
PRIOR QUESTION LEFT HERE FOR REFERENCE ONLY:
(Please advise if there is an upper age limit for pilots flying aircraft carrying only freight (not passengers) into and out of the USA?)


texts: Rotor Tip Speed vs Forward Airspeed - IAS or TAS?

texts:
I created this graph to illustrate how the tip speed of the advancing and retreating blades vary with forward airspeed but am confused as to what would be the most correct way to label the x-axis:

IAS
TAS
it doesn't matter
it depends on the application

NB: Graph is based on the following data:

  The y-axis is a derivative of the x-axis: $$y= 672 ± \frac{6076x}{3600}$$

  eg: At $x = 100KTS$, $$y=672±169 FPS$$
  From POH: rotor RPM @ 100% = 510RPM = 672FPS @ 151 inch rotor diameter


texts:
I have been reading a lot about how altimeters work, and from what I understood, most common altimeters are based of atmospheric pressure to calculate the altitude.

The question that I still have though is: If left stationary at a specific height, would altimeter change the displayed value over time? Something tell me there would be slight variation, because air pressure changes almost daily, or am I totally off with this one?


texts: Why aren't 3-surface aircraft more popular in general aviation?

texts: From everything I can gather, canards offer significant gains in performance characteristics, and most the drawbacks apply only if you remove the tail. Why not mix them together? What does Piaggio know that we don't?


texts: Could most commercial jet engines today run on ethanol without any problems?

texts:
Most commercial jet engines today would be those large jet engines on large passenger craft like a Boeing 747. Can these run on straight ethanol without any problems?

Would more maintenance be required? Would the engine lifetime be reduced? Would it be more susceptible to flameouts or other mechanical risks? Would the airplane never make it off the ground? (I imagine thrust reduction will be limit the takeoff weight.)

One reason I'm asking is because eventually petrol will be gone. (I'm not an apocalyptic saying that will happen next year, but somewhere down the line it will certainly be gone.) Will jet engines require a major redesign, or could they just use ethanol for a few years/decades and be fine?

Note: I'm talking about jet engines (turbofans, but turbojets are okay too), but not piston engines and turboprops.

EDIT: A lot of talk has been generated that ethanol contains less energy than kerosene. I assure you I'm aware of this. Ethanol is like 25 MJ/kg and kerosene is more like 40 or 45. I'm not asking this question with energy efficiencies in mind, but rather out of curiosity if the same engine geometries will work well with both fuels.

A rephrasing: Would current jet engine geometries (blade angles, compression ratios, volumetric flow, etc.) work well with ethanol instead of regular jet fuel?


texts: How can I calculate the lift force on an aircraft pulling out of a dive?

texts:
Any ideas on how this question is answered?

  Consider an aircraft dived [sic] along a path inclined to horizontal,
  perhaps even a vertical path. The manoeuvre whereby the aircraft
  recovers from this condition and is restored to level flight is known
  as a pull-out. Calculate the maximum and minimum theoretical lift
  force and its geometrical position in terms of the load factor n.


texts: Can you feel passing through the sound barrier in an F-16?

texts:
Is it possible for the pilot to feel passing through the sound barrier in an F-16?

What about other modern aircraft, will you feel anything? Do you need to go back to really dated designs before you can notice this, is it a problem of the past, or did the documentaries I watched which discussed this problem grossly exaggerate it?


texts: Which countries provide the parameters for their national height reference model in the AIP?

texts:
There is a standard in Annex 15 1.2.2.3 "When a geoid model other than the EGM-96 model is used, a description of the model used, including the parameters required for height transformation between the model and EGM-96, shall be provided in the Aeronautical Information Publication (AIP)". According to this provision, I could not find any Country which published the parameters required for height transformation between the model and EGM-96.

For example: Canada uses the Canadian Geodetic Vertical Datum 1928 (CGVD28) as its vertical reference system. The Canadian Gravimetric Geoid 2000 (CGG2000) is the scientific model of the geoid for North America.

I believe this is important for Aviation users. I want to ask if there is any country which is trying to establish the parameters in the AIP?


texts:
I've seen this video from Airbus:

This is a capture from that video:

What is the process for attaching the wings to the fuselage?


texts: What does an absolute novice need to learn to make a successful emergency landing?

texts:
Suppose I am a passenger in a small, non-commercial plane (e.g. at most 8 seats), and the pilot suddenly dies or is otherwise incapacitated mid-flight. Suppose further that nobody else on the plane knows the first thing about flying, or that I were the only other person on the plane. I understand the basic physics of flying, and have been in airplane cockpits before for a ride, but never piloted one. Cockpits are an intimidating bank of switches and dials, and I imagine I'd have very little time to acquaint myself with them experimentally in an emergency.

What minimalistic, general information should I know in an emergency situation to try to land a small plane?

I'm looking for perhaps 5–10 fast-and-simple rules-of-thumb that would be useful in a life-or-death situation, yet easy to remember.

A great answer might include 2–3 sentence answers for things such as:

Where might I expect to find certain, key controls?
How could I contact air traffic control?
What kind of terrain should I aim for, if possible?
What rate of descent is too dangerous?
How to deploy landing gear? (What might this button look like?!)
How to control the aircraft speed, and how slow is too slow?
How might I determine a good angle of attack?


texts: What is the fastest unpressurized aircraft?

texts: What is the fastest unpressurized aircraft with oxygen  masks that can carry people?


texts: Under what conditions would a helicopter be allowed to fly at low altitude over populated areas?

texts:
Yesterday, the Department of Energy was flying a military helicopter at low altitudes over Boston and the surrounding area as part of an experiment of some type to measure radiation.

I saw one of these aircraft when I driving through Watertown and in fact it passed right over me. It was operating at a very dangerous altitude. Any kind of engine failure would have created a multiple fatality situation. Normally, aircraft do not fly at high speed below 500 feet and when helicopters descend below 500 feet they normally do so cautiously and in an area they know to be safe. Having a large helicopter flying at high speed over a dense city at 100 feet AGL is very dangerous and against FAA regulations.

The type of helicopter was not the civvy type pictured in the news story, it was a Chinook. For NASA to be circulating a photo with a little civvy helicopter and then actually flying around a big Chinook I thought was pretty deceptive on their part.

I have not filed a pilot complaint about this because I assume some kind of special "permission" or exception was created to allow for this dangerous activity. Does anybody know the legal authority involved here and conditions?

BTW, I did not check the NOTAMs and did not get any NOTAMs in my mailbox on this, so if somebody can link the NOTAM that would be useful.

Update: this may have been a medevac flight, with emphasis on the word "may". Apparently, in some cases military helicopters are used for medevac flights to Burlington. However, if it was, the pilot was hot dogging and off the normal routes, both of which are serious regulation violations, but nevertheless I am told some military pilots disregard the rules.


texts: How can reducing power too quickly on a piston engine damage it?

texts: In many places, it's been stated that you should reduce power slowly to prevent engine damage.  Depending on who you talk to, some say you should reduce the manifold pressure by 1 inch per minute, others say two. However, I'm not sure just how reducing power quickly will damage an engine, and if you do, what would happen. Could someone explain?


texts: Do military jets' radar jammers block their own radar? And, if not, why not?

texts:
Will a noise jammer block the fighter's own radar? If I have understood it, a noise jammer, e.g., a barrage jammer, will emit a noise signal across a wide frequency band. Won't this make it hard to interpret its own radar "hits"?

I and a buddy are trying to make a more advanced Mech game where we want to model the ECM war a bit more. So we are trying to learn :).


texts: Which country would employ foreign air traffic controllers?

texts:
Air traffic controllers from Pakistan hold ICAO approved Licences (ATCL).
Which other country will accept this ATCL for employment acceptance?


texts: What causes a "BATT DISCHARGE" CAS message on the Phenom 100E?

texts:
In the Phenom100 POH the descriptions for the "BATT DISCHARGE" CAS message is "During a normal system operation, at least one battery is discharging."

I'm a bit confused as to what exactly does normal operation mean.

Do I get the message as soon as I turn on both batteries ?
Does it show during the starting sequence if the GPU or other StarterGenerator is connected ?

And most important where can I find this information? I have not been able to find it in the POH or any other manual

I've also found this video on youtube but it seams to be from an older version and while it is showing the message during the first engine start it doesn't show it for the second when BATT1 should be discharging for sure because it's used to power the DC buses. Moreover this video contradicts what I know for sure from the EV and the simulator.

I've also checked the K-codes for this particular CAS message and it has none


texts: Can a jet engine benefit from nitrous oxide boost?

texts:
I just read this wiki article again about the GM-1 boost system. This was used in Nazi planes during WW2. It injected Nitrous Oxide (N2O) into the supercharger of the piston engine. The idea was to get more oxidizer in the engine, allowing for higher fuel-injection and therefore higher engine power temporarily. This could serve to climb faster or take-off better or maintain high altitude.

My original interpretation of the GM-1 system and the related MW-50 system is that they're sorta like afterburners of their era. But that analogy is not perfect. Afterburners use the same jet fuel as used inside the engine, but sprayed outside the back. GM-1 used a different fuel, N2O (actually a monopropellant with more oxidizer built into the chemical than fuel), injected inside the engine.

What I want to know is, can N2O boost work in a jet engine by injecting directly into the combustion chamber (along with increased fuel injection)? Is that a good idea for military jet aircraft (compared to afterburners)? Is it even possible without overheating something?

I'm interested in turbojets and turbofans, and would even consider a centrifugal jet engine.


texts: What exactly happened with the Flight Computers on XL Airways Germany Flight 888T?

texts:
I recently saw a documentation about XL Airways Germany Flight 888T. This made some questions rising in my mind:

Two AOA-Sensors failed (freezed) simultaneously. From Wikipedia:

  Two out of three angle of attack sensors have been frozen and rendered inoperative. System logic has been designed to reject sensor values which deviate significantly from the others. In this specific case, this principle led to the rejection of the single operative angle of attack sensor, and to the acceptance of the two faulty ones, which provided similar values, but have been stuck since cruise flight.

The Airbus "shut down" the computers because of unlogic values and displayed USE MAN PITCH TRIM. But as stated above, the Airbus rejected the third sensor and accepted the two working sensors.

What made the computers to deactivate and switch to manual mode?

Is it comparing the outside AOA-Sensors with the gyro data (Thanks to the user "mins" for clarifying the diffeence between AOA-Sensor and Artificial Horizon Data, but maybe the Airbus uses the Gyro-Data as a less ranked AOA reference, which flows into the detection of a faulty AOA-Sensor)

Why aren't Airbus-Computers switching to something like alternate law automatically, instead of deactivating the FBW and displaying a small warning?

It was really hard to form my questions and I'm sure I forgot something. But I would appreciate it if you could answer the questions.


texts: Wing vs wall to wall wing,total drag comparation at same AoA?

texts:
Compare total drag of wall to wall wing vs wing(open tips) in wind tunnel,AT SAME AoA.
My first intuition is that wall to wall wing has higher pressure drag at outward parts of wing,because side-walls "act" as big endplates,so that makes difference.Reslut is higher total drag.
But

•wall to wall wing
If aerodynamic force1 =70N and angle A = 75° Drag1 =cos75 x 70N=18.1N
•wing
Aerodynamic force2 has lower magnitude lets say 60N and reduced effective AoA is 1° ,then angle B=74°  Drag2= cos 74 x 60N =16.5N
(even if I choose 65N(only 7% reduction in aerodynamic force)drag will be smaller at wing ,cos74 x65N=17.9N)
I think Peter Kampf has best opinion,this can not be prove with data because we dont know how much is magnitude of aerodynamic force at wing is reduced compare to wall to wall wing..
Wing has tilted  aerodynamic force back but in same time has lower magnitude ,so it cant be prove is drag higher or lower,it can go in both directions.
Vector tilt back at wing is usualy very small,maybe 1°,so my general oppinion is that vector tilt back has less contribution than reduction of aerodynamic force magnitude at wing...
What is your opinion?


texts: Why do fabric skin constructions not show up much in larger single engine piston aircraft?

texts: I noticed that many ultra-lights use fabric skin but are not seen much in GA aircraft, especially compared to carbon fiber? Many skin makers advertise that it can handle that sort of weight. Is this due to difficulty manufacturing, weight, smoothness of surface, strength of material or other factors?


texts: G1000: Is it possible to balance the radio volume for pilots and passengers?

texts:
I regularly fly a DA42 4-seater equipped with a G1000 system. Sometimes my passengers in the rear seats complain that the radio volume is too loud for them but it is OK for me (intercom is just right for everybody). Reason probably is that I am using a very different headset than them which I assume has a higher impedance and thus requires more electrical power for the same audio volume. If I turned down the COM volume it would be too quiet for me.

I wonder if there is any trick to adjusting/balancing the volume in such a setup.


texts: How far away from a wing's surface does the air stream remain unaffected?

texts:
I would like to know how far above and below a wing's surface an observer must look in order to see no change to the airflow. Not simply visually but mechanically, assuming a perfect scenario. I am not particularly adept at mathematics, so if there is a rule of thumb, or a general upper boundary, that would suffice for the figure I need.

For a visual representation, a wind tunnel with smoke trails. At some point distant from the top and bottom of the wing in the tunnel, all flow lines will be identical again, implying that wings have an area of effect. How far is this point from each respective surface?

Another way to ask would be to say how far apart must biplane wings be (in a perfect scenario) for them to have no effect on each other?


texts: What exactly happens when power is reduced in trimmed, straight and level flight?

texts:
I understand that trimming an aircraft at a particular airspeed e.g. 100kts will keep the aircraft flying at that airspeed (100kts) even if you were to e.g. Lower power. This is apparently accomplished by the pitching down of the trimmed aircraft.

But I am not too sure if I understand the rationale behind the pitching down. I hope to seek advice on whether what I understand is correct:

When you elevator trim to fly unaccelerated straight and level flight (all forces balanced) at e.g. 100kts, you are relieving the pressure needed to keep your aircraft in that angle of attack that produces enough lift to counter the weight, at that particular airspeed (because any increase or decrease in airspeed also will affect lift, so speed will affect the amount of lift that needs to be created by the AOA to counter the weight so as to stay level). So if your speed starts to drop, the amount of lift that your AOA must make = increased. But since you have trimmed elevator to that position means the AOA is fixed. So what happens is that the aircraft will pitch down (trade height which is potential energy for kinetic energy so your speed increase), then your speed will be back to what it used to be and your that trimmed AOA will continue to be able to supply that exact amount of lift, which together with the lift at that same airspeed is just right to counter the weight. So the aircraft will be back to level flight again.

Since power is lowered, I would expect the aircraft to continue to lose speed and the whole cycle of pitching down then back to straight and level will go on and on.

Does this make any sense?


texts: What does a fuselage frame structure of a non-pressurized transport aircraft look like?

texts: What does a fuselage structure of a non-pressurized transport aircraft look like? I can find loads of examples for pressurized fuselages, but almost nothing for non-pressurized ones. The DHC-5 Buffalo comes to mind, but I can't tell how the fuselage frame is made, e.g.- how the I-beams in the floor are laid out, etc.


texts: What skills do aviators have uniquely that could cross over to another industry?

texts: I have developed sensitivities to several chemicals used in aerospace. I have to make a shift away from our industry, so I would like to know what are qualities in aviators that would be unique and set us apart from other candidates in a good way. One that immediately comes to mind is our respect for inherent risk. What other tacit knowledge or soft skills apply?


texts: I have a PPL in Australia and own a plane. I am wondering if I am legally allowed to hire my plane out to other pilots and make money?

texts:
I have found multiple answers that state I can lease to a school and things like that but I need to know if I can hire my plane out privately to other pilots (I.e mates) And actually make a profit from this. I won’t be flying it to make profit just through the hire costs. Note: I am in Australia and it’s an experimental (vans rv6)
Thanks!


texts: Can you have TCAS RA if your other traffic only have TCAS TA?

texts:
If you fly and have a TCAS TA, it announce "TRAFFIC, TRAFFIC!"

However, the other traffic executed a TCAS RA and did the "UNKNOWN" manouvre.

Is it possible? As what i remember, it does takes two aircraft in RA mode. Unless you selected TA MODE ONLY.

Please give me reference about this.

Thank you


texts: Why do some countries separate a transition level and a transition altitude?

texts:
The US airway system uses a single transition level (or altitude), but some other countries like China separate a transtion altitude and a transition level with the transition layer in between.

Could anybody kindly explain why they use this type of separate transition system? I can guess it's there to prevent possible mid-air collisions between two aircraft using two different altimeter settings (QNH and QNE) but I don't understand how exactly that works.


texts: Why do they tell you to tie your lifevest on the left side during safety briefings?

texts:
This might be UK specific, given I have only been flying internally recently.

During the safety briefings, when describing how to inflate the lifevest the instructions are always:

"Wrap the lines around you and tie them using a double knot on your lefthand side".

I have asked the crew and none of them can tell me why and I cannot find any reason online there is an emphasis on the lefthand side.


texts: When do pilots have to submit position reports?

texts:
While over non-radar controlled airspace (e.g. the North Atlantic, the Pacific, or over vast parts of Africa), pilots will submit position reports. Is there a regular time interval in between position reports, or is that only dependent on reaching a waypoint in the flight plan? What happens then, if waypoints are hundreds of miles apart (which would be the case for example over northern Canada)?

Can the position reports be also submitted via CPDLC (Controller-Pilot Data Link Communication)?


texts: Why are taildraggers considered more rugged than tricycle?

texts: Not trying to get into the age old debate of which is better. From mechanical perspective, all landing gears are just long cantilevered beams. With a greater instability, one would expect tail draggers to not be preferred for a rough ground surface.


texts: What does the FAA mean by "Make and Model" of aircraft?

texts:
Short Version: How does the FAA define the terms "make" and "model" in regulatory documents, particularly in the context of referring to pilot experience in aircraft?

Long Version
In  14 CFR 135—and doubtless elsewhere in 14 CFR—the FAA occasionally uses the terms "make", "model", or some combination of these, such as "make and model".
Specifically, §135 gives requirements for pilot experience to be eligible for certain operations, such as to operate under "eligible on-demand" rules or to act as PIC.
See, for example, 14 CFR 135.4, "Applicability of rules for eligible on-demand operations":

(3) Pilot operating limitations. If the second in command of a fixed-wing aircraft has fewer than 100 hours of flight time as second in command flying in the aircraft make and model and, if a type rating is required, in the type aircraft being flown, and the pilot in command is not an appropriately qualified check pilot, the pilot in command shall make all takeoffs and landings in any of the following situations: [omitted for brevity]
(4) Crew pairing. Either the pilot in command or the second in command must have at least 75 hours of flight time in that aircraft make or model

See also, 14 CFR 135.105, "Exception to second in command requirement: Approval for use of autopilot system":

No certificate holder may use any person, nor may any person serve, as a pilot in command under this section of an aircraft operated in a commuter operation, as defined in part 119 of this chapter unless that person has at least 100 hours pilot in command flight time in the make and model of aircraft to be flown and has met all other applicable requirements of this part.

See also, 14 CFR 135.244

(a) No certificate holder may use any person, nor may any person serve, as a pilot in command of an aircraft operated in a commuter operation, as defined in part 119 of this chapter unless that person has completed, prior to designation as pilot in command, on that make and basic model aircraft and in that crewmember position, the following operating experience in each make and basic model of aircraft to be flown:

In contrast to the foregoing, the FAA often uses the term "type" to refer to the group of aircraft that the pilot must be experienced or trained on. An example of this would be §135.225 (e), where a pilot is required to have logged 100 hours as pilot in command in that type of airplane.

My question is, what does the FAA mean by these terms, and how should we apply them?
I would typically understand the term "make" to refer to the manufacturer: Cessna.
I would typically understand the term "model" to refer to the basic model, without reference to sub-model designations: 172 (but not 172M vs 172R). However, note where the FAA uses the phrase "make and basic model", to make this idea clear, perhaps in contrast to a separate meaning where the word "basic" is omitted.
Type, in reference to pilot certification, seems clearly to refer to all types encompassed by a type rating designation.
To apply this, would a pilot's time in a Cessna Citation 550 Bravo count toward the time required when operating a Cessna Citation 560 Encore? What about in a Cessna Citation 500 or a Cessna Citation 560 Ultra? All of these fall under the same type rating.
Does the FAA offer some guidance on this, or is there a letter of interpretation perhaps?


texts: How do FAR 23 takeoff requirements compare to FAR 25 requirements?

texts:
What types of factors come into account when planning takeoff performance for dual engine aircraft under FAR 23, compared to the aircraft with certified takeoff distances under FAR 25

Obviously, the margin for light aircraft would be less, but does this difference make a significant change in the required (legal) distance or is it less that it seems?


texts: Can I fly through these military airfields' class C airspace?

texts: I am a low time private pilot now based in Pensacola. I’m a bit unsure how the Class C of PNS/NAS Whiting Field is handled. As you can see they all overlap. PNS is a civilian field while the others are military. If I was going to fly VFR to the northeast, can I fly through the Class C of Whiting field? I always get flight following when departing.


texts: Wouldn't a Snow Globe prevent pilots from getting disoriented?

texts:
Several times in aviation history a passenger aircraft has crashed just because the pilots were disoriented. They simply just did not understand what was the position of the aircraft that moment.

Wouldn't a Snow Globe prevent this?

There are 'earth' and 'snow'. Their position inside the glass bubble would give better clue of the position of the aircraft than current mechanisms.

One could also design a specified version for aircrafts. Maybe just bubble of glass filled with pebbles.

I think it would work brilliant as artificial horizon.

Has there ever been an experiment with 'snow bubble' as artificial horizon?


texts: What are the strategies for getting familiar with a GA aircraft before considering a purchase?

texts:
Looking over the comments and answers in this question got me to thinking: How does a new pilot get familiar with the large variety of GA aircraft when contemplating a purchase?

Initially there's a vast number of aircraft to even be aware of—for example, I'd never heard of a Citabria before today. So I suspect it would be easy to overlook the perfect aircraft by virtue of simply never having a chance encounter with it. I suppose the answer to this is to attend airshows and fly-ins.

Then obviously some considerations can be satisfied with light research, such as seating and performance characteristics. But outside of that, once you have a short list, how does a pilot go about getting a "test drive"..?

Like so many before, I'm presently learning in a 172. Afterwards, though, I'd be interested in getting endorsed for a low-wing. A nearby FBO offers training in Piper Arrows—but what if I was curious about flying a Mooney, or a V-tailed Bonanza ..or a ..Citabria?? :) How do the Mooney pilots get their first flight in one??

I'm mostly interested in light, single-engine models, and I realize this question is rather conversational, but I'll appreciate any insights.


texts: How do electric propeller governors (or electrically controlled governors) work and what are their pros and cons?

texts:
I am trying to understand why electric propeller governors are not (yet) prevalent given that they offer the ability to control the RPM with high accuracy. What is the typical architecture for an electric governor or electronically controlled governor? What are their pros and con?
As far as I know, there are two types of electric governors:

The governor has an electric actuator in the propeller hub like the Airmaster Governor. This removes a lever, but adds a number of switches in the cabin.

The governor is still hydraulic, but an electric actuator controls its position. (I think the PC-12 and TBM700 work like this?)

I am assuming that option 2 is not ideal as you need a separate actuator to control the governor cable.
I guess I do not understand how airplanes like a PC-12 or TBM700 (that only have a single lever in the cabin) regulate propeller RPM.
Thanks!


texts:
CNN's French inventor makes 'beautiful' flight across Channel on hoverboard reports that:

  "French inventor Franky Zapata has successfully crossed the Channel on a jet-powered hoverboard for the first time, after a failed attempt last month.

Later in the article it says:

  The inventor said that he tried to "take pleasure in not thinking about the pain," even though "his thighs were burning."

What is it exactly about flying a Flyboard across the English channel that made Zapata's thighs burn? 20 minutes of standing shouldn't be that stressing, what is it exactly about flying this board that requires so much muscle activity that it would be painful?


texts: Why would the Speedbrake be required for such a long time on approach?

texts:
As far as I was aware, the Speedbrake is designed to slow the aircraft down. On landing, I do understand why they are required. Once the aircraft has hit the tarmac, they are deployed to 1) slow the aircraft and 2) prevent the aircraft from bouncing up and down. The airflow over the wing increases doesn’t it? To ‘push’ the aircraft down, as I say, preventing it from jumping up and down.

I have (7 hours ago) just landed on a B757, but the Speedbrake was up pretty much for 70% of the descent and approach.

Thinking back to my previous introductory paragraph, the reasoning must have been excessive speed, no? Or a need for the aircraft to slow down dramatically. Is this the case, or am I missing something obvious?

I know Air France flight 447 considered deploying the Speedbrake when their Airbus gave them faulty warnings of speed and altitude; it was advised then that this would have been completely the wrong thing to do.

I have never seen it before, as much as I did today on descent, and I wonder why the Speedbrake was required for near on 70% of our approach?


texts: Does lift coefficient for maximum range change for a glider experiencing headwind?

texts:
When a glider or unpropelled aircraft experiences headwind, I understand that the flight velocity and sink velocity for the "new" maximum possible range both increase (see velocity polar from How does wind affect the airspeed that I should fly for maximum range in an airplane?).

Intuitively I would think this means that $C_{L}$ needs to decrease so that the now higher $\frac{1}{2}\rho v^2$ can be compensated (small glide slope assumption $L \approx G$ i.e. $L >> D$).

For the theoretical $C_{L_{R_{max}}}$ equation for a symmetric $C_{L}-C_{D}$ polar, I don't see this playing a role:

$C_{L_{R_{max}}}=\sqrt{C_{D_0}\pi\Lambda e} $

...as $C_{D_0}$ to my knowledge doesn't change with velocity.

Does lift coefficient $C_{L_{R_{max}}}$ for maximum range change for a glider experiencing headwind?


texts: What are the different types of take-off minima at the bottom of a Jeppesen airport diagram?

texts: Anyone that could explain the bottom plate, what’s the difference between all those minima?


texts: Is there an online source for European Instrument Approach Procedures?

texts: The FAA offers instrument approach procedures on their website free of charge (FAA Charts).  Is there a similar site provided by EASA or the EU?


texts: Are there any accident reports that mention hacked/compromised avionics as a factor?

texts: Does anyone know of any documented examples of airline accidents caused by hacked or otherwise deliberately compromised avionics?


texts: How do you calculate wave drag of a cone as well as friction drag?

texts: I need this for a python program, so I would appreciate it if you made it possible to input it into a computer. No graphs please, just a formula to calculate the wave and friction drag of a cone. Thanks!


texts: How to calculate the drag on an airfoil from momentum equation (Fundamental of Aerodynamics 5th edition, J.D.Anderson)?

texts:
If you got the book, please read 2.6 section (page 135). Here is my sumary of this section:

An airfoil in a wind tunnel (wingtips were butted against both sidewalls of wind tunnel). The control volume is 'abcdefghia', it has unit depth in the z direction (perpendicular to the page). Through some steps that you can read from pages, we got:
$$ Drag\space on \space the \space airfoil =  -\unicode{x222F}_{ai+bh}(\rho \vec V.\vec {ds})u $$

In experinment, how can we know where the line bh is, how long it is..?

In the picture above, can we move line bh backward (to the right) ?

How big is the wind tunnel or how far from top to bottom walls of the wind tunnels (with given airfoil)is in oder to have the lines ab and hi ?

Do you feel this method is very inaccurate with a lot of negligibly and pitot rake thing (page 141) ?

@Peter:
Thank you, nice to hear that !! . Actually, I thought I understood this section until I face the problem 2.2 at page 198 (by the end of chapter 2). I reviewed this section and a lot of questions arised. First, sorry because English is not my mother language.

1st question: I really have no idea where the line bh is (both in vertically and horizontally) and how is the length of bh ?.

2nd question: Suppose we already have the line bh located properly. My physical feel tell me that the line bh can move backward and the velocity gradinent $ u_2 $ = f(y) stay the same. But imagine in real life, if we move the line bh far enough, the velocity gradient $u_2$ will be uniform and equal the freestream velocity $u_1$ !!

About the third question, I think: we must have top and bottom walls of the wind tunnel that the pressure over them is equal to the free stream pressure, I mean: move them far from the airfoil in vertical direction so that the pressure over them is uniform and equal to freestream pressure.

4th question: I still had no idea because I never use my hands to do these kind of experiments, but my instinct tell me it will have a lot of errors.
My word maybe too dumb but I'd like to learn what people do in real experiment.


texts: Under which conditions is full rated power instead of METO power required for takeoff (DC-3/C-47 with Pratt&Whitney 1830 twin wasp engines)?

texts:
OK, so my explanation is going to be quite long, but please bear with me. My question is in two parts, but first I'll explain what I know.

I was reading the C-47 Pilot's Flight Operating Instructions and the DC-3 Organisation Control Manual, and they both say that takeoff should be performed at full-rated power.
This link shows a bunch of good reasons why one should always use maximum power for takeoff

[FAA mandatory for commercial operations; P&W endorse it;

  'The distance the pistons travel in the cylinders (stroke) is related
  to the power used. The piston rings, over time, wear a ridge into the
  cylinder wall at the top and bottom of the stroke. If 42" is used for
  takeoff, the bottom ridge will develop further up the piston wall than
  in an engine that has seen rated power for Takeoff. If the time comes
  when full rated power is needed (short runway, engine failure, etc.)
  and a power setting greater than 42" is used, the piston is now forced
  past the ridge in the cylinder created by many hours of using de-rated
  power. Forcing the piston rings past this ridge can cause them to
  break'

;carburator has additional cooling feature past 45"; engines last longer],

but also mentions the fact that full-rated should only be used for one minute at a time (which is apparently one of the reasons some people choose to take off with METO power instead).

One minute sounds like a very short time to me (and to the person defending T/O with METO power), but I'm not a pilot, so I do not know how long a  normal T/O roll with a DC-3 at maximum takeoff power  would take.

The DC-3 performance information sheet (found here) mentions that (at sea level and normal runway conditions) a 1700 ft T/O roll is enough to reach 100 mph (which I am assuming is the minimum takeoff speed ), but it says nothing about how long  the DC-3 would take to reach that.

They also mention that at 5000 ft altitude it'd take a 2300 ft T/O roll to attain that same speed. But that still doesn't tell me how long that would take because I don't know the acceleration rate the DC-3 has. I've checked the charts, but I admit I couldn't conclude anything from them (doc is semi-readable, plus, it might have been way over my head anyway). I'm sorry if this question is stupid, maybe I need to brush off my physics , but I really am not managing to figure this one out on my own ...

I am aware there are a number of variables that come into play here, but I'd be happy if anyone could give me an approximation , or even an example of what conditions need to exist for the DC-3 to take only a minute to do the T/O roll (if one wanted to use full-rated power).
And, more importantly: Would a wet grass runway at an almost 6000 ft altitude airport, plus having the aircraft at maximum takeoff weight (or close to it) justify choosing to take off with METO instead of full-rated power? I mean, such a T/O roll would definitely take over a minute, right?

Thanks a lot


texts: Where does turbine vane and blade cooling air come from?

texts:
Some large jet engines have a high combustion temperature to increase maximum thrust. First vanes and blades of the turbine must be cooled to prevent them from melting. One method is to circulate cold air from the compressor inside the element and/or create a coating of air on the element faces using channels and holes.

Trent turbine HP blade with cooling channels, source

How is air from the compressor channeled to the vanes and blades? How is cooling air prevented to escape to the space between rotor disks instead of going to the cooling channels, under turbine gases pressure?

What approximate fraction of core power is used for such cooling?


texts: Is it legal to begin pilot training on a jet?

texts:
Disregarding financial and difficulty concerns, would it be possible (legal) for someone to obtain a PPL license on a jet aircraft?

If it is possible, would there be any restrictions on the license on operating piston engine aircrafts?

EDIT: the linked question asks about EASA regulations. This question is about FAA regulations, thus, the answer in the linked question does not apply.


texts: Could I use a powered parachute to fly around New York City?

texts:
NYC traffic is so horrendous that it would be pretty convenient to be able to take off with a powered parachute (PPC) from the top of a building or from a park and be able to fly above all the traffic to your destination. I'm wondering if anyone has any insight into this.

I know the class B extends to the surface in upper Manhattan but how about downtown? Class B starts at 1100' (plenty of space for a PPC); could one fly around there without talking to anyone? Also, could one potentially get a class B clearance to fly around at low altitudes in upper Manhattan?

Finally, does anyone know how much space a PPC can take off in? Is there any way a STOL PPC could take off from an NYC rooftop (or more realistically an open space such as Central Park)?

Don't give this question too much thought, just something fun to consider. I think the real limitation would be regs here, even if you could go to the Great Lawn or something to take off.


texts: Has any accident been caused by poor time management, despite a perfectly done checklist?

texts:
This is a question I've heard from an aviation psychologist. I've searched on that but couldn't find a satisfying example. The full question is:

Has there been any accident which was caused by poor time management by the crew, despite a perfectly done checklist?

Thanks in advance.


texts: Why are combi airliners no longer being built?  Is the reason structural, economic or regulatory?


texts: Is there a 3-dimensional airspace viewer?

texts:
I am using SkyVector to have an idea of what the airspace looks like in terms of waypoints and airways.

I was wandering if anybody knows a website that displays such information but in 3D (or 3D + time) in order to navigate through the airways and check out some information as viable flight levels or altitude constraints.

I am imaging of a website/software that allows to navigate like on google earth or cesium and see what the airspace is like (qualitatively at least).


texts: What are the pros and cons of having canard control surfaces versus a horizontal tail control surface?

texts: For a normal civil aviation aircraft, what are the pros and cons of having Canard control surfaces or horizontal tail control surface?


texts: What is the form of information stored in black box?

texts: Black boxes contain the information regarding to a flight. What is the form of those information? Any particular language log?


texts: Relationship Between Aircraft Thrust and Jet Exhaust Velocity?

texts:
What is the relationship between aircraft thrust and jet exhaust velocity & thrust and mass flow.

Actually, my question is how to reduce or decrease jet noise without decreasing the thrust ?


texts: What educational qualifications are required to become a pilot in the UK?

texts:
In order to obtain a pilot's licence in the UK, are any formal educational qualifications (such as school-leaving certificates) required?

As well as any statutory or other formal requirements, do employers of commercial pilots typically require any education qualifications? Or is holding a pilot's licence generally all that is needed?

In the absence of relevant educational qualifications, are there other skills, capacities or demonstrable advantages that would help someone who lacked them, but still hoped to become a pilot?


texts: Where can I find airport diagrams from airports all over the world?

texts:
I am trying to build a database of airport diagrams (PDF documents). For the US, the FAA seems to be the best source. Are there any other free sources for Europe, Asia, etc...

Also the data needs to be reliable.