texts: Have any aircraft ever been attacked by chemical, biological, radiological or nuclear weapons? Information security compromises?

texts:
Have any aircraft, military or civilian, ever been attacked by chemical, biological, radiological or nuclear weapons?
Terrorist attacks and test firings included. Attacks on persons on-board the aircraft (rather than the aircraft itself) included.
Information security attacks on the aircraft itself (such as computer viruses) would also be of interest, although I'll exclude jamming of communications and sensors such as radar.
Sources I've already consulted:

Airport and Aviation Security, Elias
USACBRN School, Wikipedia
The Jihadist CBRN Threat, Stratfor
Flying High, Flying Safe, Wolff
Practical Aviation Security, Price & Forrest
Counterterrorism: A Reference Handbook, Steven & Gunaratna

Definition of 'chemical weapon': sure, explosives are made out of chemicals (as is everything else) but I'm talking about chemical weapons as defined by the Organisation for the Prohibition of Chemical Weapons:

The term chemical weapon is applied to any toxic chemical or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action. Munitions or other delivery devices designed to deliver chemical weapons, whether filled or unfilled, are also considered weapons themselves.
The toxic chemicals that have been used as chemical weapons, or have been developed for use as chemical weapons, can be categorised as choking, blister, blood, or nerve agents. The most well known agents are as follows: choking agents—chlorine and phosgene, blister agents (or vesicants)—mustard and lewisite, blood agents—hydrogen cyanide, nerve agents—sarin, soman, VX.

For 'radiological weapons', I'm not talking about visible electromagnetic radiation (light) or invisible electromagnetic radiation (radio etc) but rather radiological dispersion devices, defined by the US Department of Defence as:

any device, including any
weapon or equipment, other than a nuclear explosive device, specifically designed to employ
radioactive material by disseminating it to cause destruction, damage, or injury by means of the
radiation produced by the decay of such material

Ford, J. (March 1998). Radiological Dispersion Devices: Assessing the transnational threat. National Defense University - Institute for National Strategic Studies - Strategic Forum, No. 136. as cited in Rickert, Paul R., "The Likely Effect of a Radiological Dispersion Device" (2005). Faculty Publications and Presentations. Paper 47.
'Biological weapons' as defined by the United Nations:

Biological weapons are complex systems that disseminate disease-causing organisms or toxins to harm or kill humans, animals or plants. They generally consist of two parts – a weaponized agent and a delivery mechanism. In addition to strategic or tactical military applications, biological weapons can be used for political assassinations, the infection of livestock or agricultural produce to cause food shortages and economic loss, the creation of environmental catastrophes, and the introduction of widespread illness, fear and mistrust among the public.
Almost any disease-causing organism (such as bacteria, viruses, fungi, prions or rickettsiae) or toxin (poisons derived from animals, plants or microorganisms, or similar substances produced synthetically) can be used in biological weapons. The agents can be enhanced from their natural state to make them more suitable for mass production, storage, and dissemination as weapons. Historical biological weapons programs have included efforts to produce: aflatoxin; anthrax; botulinum toxin; foot-and-mouth disease; glanders; plague; Q fever; rice blast; ricin; Rocky Mountain spotted fever; smallpox; and tularaemia, among others.


texts: Why does the A320 IR2 MEL OPS procedure suggest to switch to ADR3?

texts:
The A320 34-10-05B IR2 MEL OPS procedure additionally calls for Air Data switching to FO3.
When ADR 2 is working fine why replace its data on the FO PFD when only IR data is lost?


texts: Are flight schools required to verify citizenship of all students?

texts:
Is the requirement to confirm citizenship and provide a logbook endorsement required for those who already hold a pilot certificate?

Does another instructor's prior endorsement that confirms citizenship was verified act as a substitution for subsequent instructors, or does each instructor need to check and make their own endorsement verifying citizenship no matter what? This is with the assumption that there are multiple freelance CFIs rather than a flight school employing many CFIs who take turns teaching the same student.

If no, would that not imply that each flight review with a new instructor would need a new citizenship verification or are currency checks exempt?


texts: How does one determine the freestream and ultimate slipstream velocities to estimate thrust?

texts:
The task before me is estimating the thrust of a propulsion system (a ducted fan) using this equation for thrust (Eq. 2.1.1)1:

$$T = (mass\; flow\; rate)\;(slipstream\; velocity - freestream\; velocity) $$

I know what the ideal inlet and exit velocities of the system are, but how does one determine the freestream and slipsteam velocities so that estimated thrust may be calculated?

1 Warren F. Phillips, Mechanics Of Flight Second Edition, John Wiley & Sons, Inc., Hoboken, New Jersey, 2010, p.153


texts: How far are shortened replies to ATC allowed to go?

texts:
Pilots often use non-standard-phraseology for readbacks. Some examples:

  ATC: DLM, switch to tower, 121.2

  P: tower, for DLM

or

  ATC: DLM, identified, climb via the RIDA9 departure

  P: roger, climb via, DLM

or

  DLM, cleared for takeoff runway 17

  P: cleared for takeoff, DLM

The last two example are from two videos by Boldmethod, How To Fly An IFR Departure Procedure With A "Climb Via" and How To Fly An Instrument Arrival Procedure (STAR), used by an ExpressJet-pilot.

Especially the two last ones were a bit shocking to me when I heard a professional pilot using them. So I now want to ask, how far is this "ATC-Slang" allowed to go?


texts: Why did Avianca have A318s with PW6000 engine?

texts: I want to know about the upgraded PW6000 Avianca A318s. Why did those get upgraded? Did they not produce enough thrust already?


texts: Is there an actual rated thrust for a Cessna 172 engine at takeoff power?

texts:
I could approximate the thrust by knowing the weight of my aircraft and timing the acceleration to takeoff speed, but I think that would be a little dangerous of me as well as only an approximation due to rolling and wind resistance as well as inaccuracies of the airspeed indicator.  I also realize the thrust would vary as airspeed increases due to changes in propeller and engine efficiency.

Nevertheless, was there every an actual rated or measured thrust for the C172?  You can use whatever year model you want, although I usually fly the C172N at 160Hp using a stock propeller.  I would also assume if there was a measurement, it would be at standard atmospheric conditions (sea level, 15C, standard 29.92 pressure).


texts: Is there a way to obtain real-time METAR data?

texts: I know that METAR data are available at hourly intervals from the US National Oceanic and Atmospheric Administration (see e.g. the report for Karpathos Airport, Greece ).  However, I would have thought that at the age of the internet it would have been possible to obtain (near) real-time data regarding an airport's weather.  Is such a service available?  Is there a better (more frequently updated) internet-accessible source for global METAR data than NOAA?


texts: Which aircraft feature stock exterior cameras?

texts:
Watching a video on YouTube of an A340-600 takeoff, I noticed that it has at least two exterior cameras — one for lining up the nosewheel, and the other on the tailfin:

After the NTSB recommended the use of exterior cameras in 2012, I'm wondering how widespread these are? Which models of Airbus aircraft have them? Do any Boeings?

Do these record or are they realtime-only?


texts: Are there regulations on building homes at the end of a runway?

texts: I live next to a golf course (Butter Valley Golf Port) in Bally PA that has a paved single engine air strip that runs through a portion of the course.  Off the end of the runway (in one direction) perpendicular to the end of the runway is a single lane public road that runs in both directions.  I live on this road down the street from this same end of the runway. Currently on the opposite side of the road at this end of the runway is 80 acres of farmland.  A developer has submitted plans to build 236 condos on this 80 acres directly across the street from the end of the runway.  Are their regulations about building homes on the landing/take off flight path of a registered runway?  Where could I find these regulations?


texts: Why do I have to turn off my (non-cellular) iPad before takeoff?

texts:
Every time I travel on an airplane, the stewardess forces me to shut down my iPad.
I just lock it, and start using it again 5 minutes later.

I wonder why this is? Is it because I have to have my hands free if the airplane crashes? Or is there any other logical explanation?


texts: I have a Grumman AA1. It’s been modified several times through stc’s to increase power and speed.  The aircraft requires full nose down trim to fly level in cruise. Is there a way to calculate the perfect angle of incidence of a horizontal stab for a given airspeed? It’s set at -3deg now, I wonder what moving it to 0deg would do? I have all kinds of load data for the horizontal stab.


texts: How did the windshield technology evolve?

texts:
I would really appreciate it if someone could please explain the differences and similarities between the cockpit windows of a Boeing 747-400 and Douglas DC-3.

I am just trying to figure out how the technology would have evolved, what aspects would have remained and what would have changed. Literally just a brief comparison - nothing technical.

I have been unable to find information specific to the two models. I have found out the basic information with regards to a cockpit window, but I am unsure as to whether it applies for a Douglas DC-3 as well.


texts: Do carriers such as Janet Airlines carry ADS-B transponders?

texts:
I was doing some casual browsing and came across some videos related to Janet Airlines. This is something I remember hearing of many years ago but this happened to jog my memory.

What jurisdiction would such an airline fall under? From the Wikipedia article:

  Due to the secretive nature of the airline, little is known about its organization. It is operated for the USAF by infrastructure and defense contractor AECOM through AECOM's acquisition in 2014 of URS Corporation, which acquired EG&G Technical Services in 2002, as derived from URS's history of providing this service to the Air Force and job openings published by URS.

If it's strictly military (all staff appear to require clearances, after all), would such planes be fitted with ADS-B transponders by regulation? If so, couldn't they just be looked up on websites like Flightradar24?

Also, if an emergency occurred on board, what special treatment (if any) would they be provided if they landed at a civilian airport?


texts: Can I legally land an airplane in in Badwater Basin, CA?

texts:
Would it be legal to land a light plane in the Badwater Basin salt flats in Death Valley National Park?

Let me add that you can obviously land in the park, as you have runways at both Furnace Creek and Stovepipe Wells. So another way of asking is simply: do you have to have an official runway to land? Obviously, you would need to stay >= 500 feet from people, but people don't typically wander too far from the parking lot and that's a big area. Staying away from people wouldn't be too difficult, especially in July or August when there's basically no one in Death Valley.


texts:
Is there anywhere where I can find a database of experimental or CFD-obtained NACA series four or series 6 airfoil data?
I'd like to have access to a relatively large set of high-fidelity drag polars/$C_L \times \alpha$ curves in order to train a neural network for a personal project, and I don't have the time to digitalize the plots in NACA's original contractor reports.
Any help is appreciated. =)


texts: Can Bell-lift distribution increase glider efficiency(L/D)?

texts:
Can a Bell-lift distribution without a rudder has higher overall efficiency (L/D) then current gliders, if the wingspan is not limited?
(Is it really possible that most of aerospace engineers don't understand the essence of Al Bowers' PRANDTL project?
What is stopping the aero-industry from accepting his "new" design ideas? Is he wrong, or do they not want the risk of an unproven concept?)
AL Bowers say at 13:20 that Bell distribution increase L/D ratio by 12.5% ! ?


texts:
US has bought or sourced many Russian fighter jets.

Was any Russian design feature incorporated in modern US fighters jets or vice-versa?


texts: Why are the aerodynamic characteristics of a finite wing different from the properties of its airfoil section?


texts: Why do flight attendants on the 787 lock the dimmable windows at different phases of the flight?

texts: I’ve heard of many passengers complaining about the FAs locking the dim setting at different phases of the flight. Seems to be something the passengers definitely don’t like. And the passengers cannot change it. What is the reason for locking the window brightnesses?


texts: Are there ILS approaches where a non-precision procedure isn't allowed?

texts: Are there ILS approaches where the LOC/non-precision procedure isn't authorized?


texts: Why do simultaneous-ops parallel runways need to be so far apart?

texts:
In the answers to this question about Denver's widely-scattered pinwheel of runways and this question about Schiphol's runway out in the middle of nowhere, it's mentioned that parallel runways are required, by both European and U.S. regulations to be over a kilometre apart in order to be able to have simultaneous departures or simultaneous arrivals on both runways.  In contrast, if one runway is departing an aircraft while a parallel runway is landing an aircraft, the runways need only be a few hundred metres apart.

Why is there such a large runway-separation requirement for simultaneous arrivals or simultaneous departures from parallel runways?  It can't be for aircraft separation, since an aircraft is allowed to land on a runway quite close to a parallel runway that is simultaneously departing an aircraft, despite the possibility of this resulting in a head-on collision if one or both aircraft drift off track, so what, in fact, is the reason for this?


texts: In this 2nd brace position, should your head lean against the seat in front?

texts:
Air Crash Investigation: M1 Plane Crash (S14E01) motivated this question, the relevant timestamps for which I greened. Neither the audio or picture below (in which the hands are hiding the front of the head) explicitly resolves: For maximal safety, in the 2nd suggested brace position (on the right, timestamped at 42.10), should the head touch or rest on the seat in front?
I know nothing of physics or aerodynamics, so please explain in as simple English as possible. The original video appears too dark, so I did enhance the originals (using Gamma Correction):


texts: How are electronic systems locked and connected in the electronic bay?

texts:
On aircraft the electronics bay contains multiple systems, e.g. for the A320:

A320, photo by B-2230, source: JetPhotos
How is the electronic equipment locked (it seems there are two mobile screws) and how are the wires connected? Details will be appreciated: standards, diagrams, images...


texts:
Lift is a term that is used very frequently here, but I cannot find any post explaining what it is exactly. I am looking for the exact definition of lift, not an explanation of how it is generated.

It seems a very simple question, but I have not been able to find consistent answers to it. Some very well respected sources even contradict each other:

At https://en.wikipedia.org/wiki/Lift_(force) Lift is defined as:
A fluid flowing past the surface of a body exerts a force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction.

But according to NASA (https://www.grc.nasa.gov/www/k-12/airplane/lift1.html):
  Lift is the force that directly opposes the weight of an airplane and holds the airplane in the air.

If a plane is flying straight and level (at constant altitude) these definitions are the same, but otherwise they are not the same at all. So, which one is correct?


texts: How does a fixed-pitch propeller changes the blade's angle of attack?

texts:
Studying I have found a question that states that in a fixed-pitch propeller in flight at a given TAS, the blade's angle of attack will change if RPM increase, but I don't understand how can the blade's AOA change if the pitch of the blade is fixed.
Am I missunderstanding the concept of fixed-pitch propeller or the question is wrong?

Question answer and explanation for source:

Q:For a fixed-pitch propeller in flight at a given TAS, the blade angle of attack will:
A:increase if RPM increases.
E:For a fixed pitch propeller the pitch angle cannot be changed (it varies from root to tip to maintain near-constant angle of attack along the blade).

The angle of attack as in the case of a aircraft wing is defined as the angle between the chord line and relative airflow. With a propeller however the relative airflow is the resultant of the airflow due to rotation and forward speed. Change either of these values and the angle of attack will change.


texts: What are the duties of an ATC supervisor?

texts:
We know that each air traffic control facility has a "supervisor", a person who is "in charge of the controllers", so to speak.

What exactly are the duties of the supervisor? Here are some of the things I've guessed:

Resolve conflicts between a pilot and a controller (by assigning a different controller to the position? Taking over the radio directly?)
Assist in emergency situations (coordinate with nearby airports / approach sectors?)
Deciding when to merge / split sectors, when to bypass noise reduction procedures due to weather etc.

Am I correct?


texts: What are the characteristics of the F-16 airframe lifetime?

texts:
What limits the lifetime on the F-16 airframe? I assume it is material fatigue, but what kind, and where on the airframe?

Moreover, what exactly happens? What will happen if this problem is ignored? Will the wings break off? Will the airframe collapse or break somehow?

What can be done about this problem? Can the airframe be maintained somehow, repaired, replaced? For how long can this be done, indefinitely, or only up to a point where it is financially feasible?


texts: In the U.S., what are the requirements for being an Executive airport?

texts: Are there statutory or regulatory criteria for a facility to be called, say, Elbonia Executive Airport as opposed to County, Municipal, Regional, Field, or something else? Is it strictly marketing?


texts: Why do people say aviation regulations are written in blood?

texts: I have heard it said that all aviation regulations are "written in blood". I think this means that every rule in the book exists because someone died - and there was a lesson learned. Is this accurate? Is there anything else to the story of this phrase?


texts: What material was/is used on the skin of the Blackbird SR71?

texts: What material was/is used on the skin of the Blackbird SR71 and how was it cooled.  How was it manufactured to be stronger with age


texts: If you’ve ever seen an airliner park at its gate, you’ll likely note that sometimes it will move beyond slightly beyond its designated parking line. However, you may see that after the brakes are applied the aircraft moves back in “reverse” onto the correct parking line. It appears to me that this is as a result of gate ramps being at an angle. Is this correct? If not what are other possibilities for this phenomenon?


texts: What are the protrusions on the sides of the fuselage of the F-16I?

texts: I've noticed that the F-16I has these protrusions on the sides of its fuselage. What purpose do they serve?


texts: Are GPS airspeed meter and altimeter going to replace traditional measurements?

texts: When are GPS Airspeed meters and Altimeters going to be introduced if they not already in use?  Are they more accurate than systems in use now and? How much would it cost to install them to older aircraft?


texts: Is there a proper term to use when you're referring to the total number of people on an aircraft, including both the passengers and crew/pilots?

texts:
I've found that often when people quote the number of passengers on an aircraft, they exclude the crew/pilots, which they'll provide separately.

Is there a proper term to use when you're referring to or asking for the total number of people on the aircraft, including both the passengers and crew/pilots?


texts: How do aircraft stall warning systems work?

texts: If an aircraft stalls, there are stall warning systems called as Stall computers. Anyone has idea how they predict that its a stall and how they raise the alarm/warning?


texts: What does one do when the weather report has a bogus altimeter setting?

texts: I saw a METAR for a nearby airport that had A2248 ... SLPNO in it with no maintenance indicator.  Is the SLPNO a sign that the altimeter setting in the METAR is untrustworthy as well?  How else does one get the altimeter setting (assuming ATIS is drawing from the same, messed up data source that the METAR is -- this is an RMK AO2A METAR), or is one grounded until the AWOS reading is fixed?


texts: Non-fueled, bladeless, minimally-noisy aviation engine --- Science fiction or real theoretical science?

texts:
As a non Aeronautics expert I ask if non-fueled (electric?) vehicles which are minimally-noisy only science fiction or a real theoretical scientific concept aimed for close or very far future development?

I ask if there is any theoretical science that tries to describe how such a thing would be possible in the future...

Characteristics of such a vehicle:

Some non-fueled thrusting; if electrical, than an enough powerful battery or enough powerful solar energy exploitation mechanism
Fireless
Bladlessness: No jet, no propellers/rotors or turbines
Wingless
Silent or almost silent: Not the regular noise. Something very very quiet - at least 75% of the noise will be air molecules rotating solely from the whole objects' motion, but not from the engine itself.

This flying object may or may not be able to fly both in earth's atmosphere and out of it.
Bob Lazar's flying saucers maybe?


texts: Can planned runway closures prevent a plane from leaving an airport?

texts:
I was on a flight recently where, due to the long runway at my airport being repaired, we had to fly to another nearby airport to get enough fuel for the rest of our trip.  We couldn't take off with enough fuel for even a two hour flight because of the runway closure, and this was at a major GA airport.

I'd imagine there are runway closure regulations to prevent this kind of thing from causing serious logistic issues, but do planned runway closures ever make a trip impossible even with refueling?  Considering factors like airspace restrictions, distance, heavy cargo, etc.  it's easy to imagine that a flight normally possible could become impossible due to a planned runway closure, even if you try to refuel at the nearest allowed airport.  What airport regulations are there to mitigate this and how big of an issue is this? For example, can an airplane ever be stranded while airport construction is occurring? How are airports required to notify pilots in advance of planned closures and are there regulations to prevent stranding airplanes or causing logistic issues by closing the only long runway at a critical airport?

Note: I'm not concerned with weather-related closures here, but rather planned runway closures.  My question is aimed at GA where things are more flexible, but applicable answers from commercial aviation can be accepted too.


texts: Is the induced drag independent of wing span?

texts:
I am a new aviation student and I was reading about induced drag the other day. I know that it is produced as a result of the tip vortices and that the greater the aspect ratio of an airplane the less the induced drag force. But when it came to the equation of the force, it is equal to:

$D_i = \frac{1}{2}\rho V^2 S \frac{C_L^2}{\pi  AR \epsilon}$

If we substitute aspect ratio $AR$ with span/chord $\frac{b}{c}$  and plan area $S$ as $b\cdot c$, the span term will be cancelled and the induced drag will be affected by the chord length only.

It kind of contradicts the effect of aspect ratio on the induced drag force, doesn't it?


texts: How to know if an aircraft is climbing or descending?

texts: As a ground observer, how can you tell if an aircraft is climbing or descending?


texts: What are the checklist items for a runaway stab trim on a B737 MAX 8 and MAX 9?

texts:
This is a follow up question to this question.

This question is not directly related to the MCAS system in the new B737 MAX aircraft, instead, my question is about the checklist for a runaway stab trim. What are the items on the Boeing B737 Max checklist to deal with a runaway stab trim? (Better yet, a picture of the actual checklist would be awesome!).


texts: Why does the Tu-134UBL have a sharp/pointed nose cone?

texts:
Russian/Soviet aircraft design has always intrigued me, and even more so when coming across this photo of the Tupolev Tu-134UBL with its pointy nosecone.
Having looked up the performance characteristics of the aircraft, it "only" seems to fly at sub to trans-sonic speeds (max. speed 890km/h or Mach 0.72 at sea level).
Based on my limited knowledge reinforced by this great post, it only makes sense to use a pointy nose cone when the aircraft travels at supersonic speeds.
Therefore, would the reason for the nosecone design be for some other function rather than just aerodynamics? Radar?


texts: May aerobatics be performed over a controlled airport without getting a waiver?

texts:
CFR 14 Part 91.303 states:

Aerobatic flight.
No person may operate an aircraft in aerobatic flight--
(a) Over any congested area of a city, town, or settlement;
(b) Over an open air assembly of persons;
(c) Within the lateral boundaries of the surface areas of Class B, Class C, Class D, or Class E airspace designated for an airport;
(d) Within 4 nautical miles of the center line of any Federal airway;
(e) Below an altitude of 1,500 feet above the surface; or.
(f) When flight visibility is less than 3 statute miles.
For the purposes of this section, aerobatic flight means an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.

For the purposes of this question I want to focus on paragraph (c). Assuming we don't have any other specific permission (waiver), may aerobatics be performed above class B, C, D, or E surface airspace?
I know aerobatics may be performed under the outer rings of class B and C airspace.
There also doesn't appear to be anything preventing aerobatics above the outer rings of class B or C airspace.
So the question is focusing on the center core (the surface area) of class B and C as well as the typical cylinder of a class D airspace and whatever shape a class E surface area happens to be.
Paragraph (c) simply states "Within the lateral boundaries of the surface areas" but makes no mention of altitude (other than the 1500' AGL reference in paragraph (e)).
Obviously we are talking about surface areas that go to the ground so clearly you may not fly in or below these surface areas. But may you fly above them as long as you are 1500' AGL?
"within the lateral boundaries of" has no implied altitude restriction. That term, in English, implies surface to outer space. So it would seem that aerobatics may not be performed above a class B, C, D, or E surface area at any altitude.
But you may perform aerobatics above the outer rings of class B and C. So why restrict doing them over the surface area?
Is there an official answer? May I legally do aerobatics above class B, C, D, or E surface airspace?
I have searched and looked at many related topics but none address this specific question. Even the Hucker discussion leaves this unanswered (to me at least) which only clarifies being able to do aerobatics under (no mention of over) the outer rings of class B and C airspace.


texts: Why does an aircraft's nose tend to pitch downward at higher bank angles?

texts:
In the usual aircraft configuration, the center of lift is located behind the CG producing negative pitch moment (the horizontal stabilizer counteracts it by producing downforce - positive pitching moment). If the aircraft rolls to one side the vertical component of lift on the wings would decrease, so by that logic the aircraft should pitch up.

Why does it pitch down? What am I missing?


texts: Propeller effect on the L/D of an aircraft (Pusher Propeller configuration)

texts:
I recently performed an aerodynamic analysis of a fixed-wing UAV with a pusher propeller configuration. I found out that the L/D reduced by about 15% when compared to the body alone without propeller. I am investigating methods to mitigate this problem.

The following are some details about the aircraft,
Wing Span = 2.5 m

Fuselage length = 2 m

MTOW = 25 kgs

Tandem wing configuration. The following image is a representative image.

Courtesy: Raytheon Coyote

Any suggestions will really be helpful.


texts: What is the difference between MMEL and MEL?

texts: What was the need to introduced MEL if MMEL is there and is less restrictive than MEL ?


texts: Could an AN/APG-79 AESA radar "lock-on" a single bird?

texts:
Could a fighter pilot in 2015 using an AN/APG-79 AESA radar "lock-on" a single bird?

I know that modern radars like the AN/APG-79 in modern combat aircraft like the F/A-18F filter out false alarms with Doppler processing and use what could be called "filters". Could an F/A-18F pilot "lock-on" a single bird using STT (Single-Target Tracking) mode or by using any other radar modes?


texts: What is the most 'environmentally friendly' way to learn to fly?

texts:
As this question indicates, I've been thinking recently about the environmental impact of flying (since when automated cars are the only means of ground transport, aviation will be responsible for most greenhouse emissions).

So, as an amateur, novice pilot, I would like to know which is more environmentally friendly, learning in a glider or learning in a single engine prop (Piper Tomahawk, Cessna and the like)?

At first it seems obvious, the glider doesn't have an engine while the latter does. But if we assume the launch method of the glider is tow rope, this would be powered by a single engine prop, using more fuel than it would if it wasn't towing, plus the climb is the most fuel-expensive part of the flight anyway, leading me to think there might not actually be that much difference.

Clarification on this issue would be greatly appreciated.


texts: Why is the top left corner cut off on the cg location envelope for small airplanes?

texts:
Why does the PA-28 C.G. envelope have the top left corner cut off rather than allowing higher weights at a forward C.G. like it does at the aft C.G.?

(source)


texts: How do airliners get from the factory to the client if the aircraft does not have the required range?

texts:
Today I flew on an Embraer 190 of Kenya Airways. Checking in the tech specs this aircraft has a range of roughly 2900 km. Considering it is built in Brasil, I was wondering how do they deliver it to Africa since they would have to cross the Atlantic Ocean which I suppose is more than 2900 kms of range it has available.

Do they add temporary tanks and, of course, by flying the aircraft empty get more range out of it?


texts: Will an Airbus A320 plane go into an unrecoverable nosedive and crash if a single angle of attack sensor fails, like on Lion Air JT610?

texts:
For example, has an Airbus gone from cruise flight into an automated unrecoverable nose dive until it hit the ground because an AOA sensor failed in flight?

Moreso, are there any cases of an AOA sensor failing on an Airbus, and the plane not crashing?


texts: What does the sign "Caution your blast" mean?

texts: At London City Airport (LCY) there exists a "CAUTION YOUR BLAST" sign. This isn't one I've seen before. What does it mean?


texts: At what altitude does aerodynamic forces become negligible?

texts:
If I sail on a boat from North to South the boat will be dragged by the oceans which it floats on, and the oceans are dragged by the Earth. Now when you go higher let say 10 km an airplane will also be dragged by the atmosphere, so the plane would "feel" an aerodynamic force against the atmosphere (rotating around Earth) if it is stationary.

But when you get higher and higher the atmosphere will get less dense and the force of the atmosphere will drop, till you probably reached satellite level where there is almost no drag of the rotation of the Earth at all.

What is the altitude an airplane can no longer "feel" aerodynamic forces because the atmosphere is so thin?


texts: What's the story behind U-2 flying from aircraft carriers?

texts:
This video from the CIA YouTube channel shows U-2 aircraft launching via catapult and trapping with a tailhook:

The description only offers this:

  After stopping U-2 flights over USSR in May 1960, the IC looked for new ways to use this unique reconnaissance asset. One idea was to modify the U-2 to fly from US Navy aircraft carriers.

What motivated these experiments? Were they successful? Was the plane ever used operationally from a carrier? What would a mission objective be?


texts: How does contrail formation differ from turbofan to turbojet?

texts:
Air forces and intelligence agencies are indeed interested in predicting whether condensation trails (contrails) will be visible or not during aircraft operations.

Photo: C-CYOW at Photobucket

Among existing prediction algorithms, Appleman's method, devised in 1953, is frequently cited, even if more accurate or refined algorithms exist, like JETRAX.

From Predicting Contrails Using an Appleman Chart (Nasa), the principle is based on air saturation characteristics:

  At first, scientists were not sure how contrails formed. We now know
  that they are a type of mixing cloud, similar to the cloud that
  sometimes forms from your breath during a cold winter day.

  Appleman showed that when the air outside of the airplane is cold
  enough and moist enough, the mixture of the jet exhaust and the air
  would form a cloud.

Appleman chart, with a different layout

Since 1953, civil turbofans have replaced turbojets, with various air bypass ratios. What is the effect of this replacement on the occurrence of contrails?

Does turbofan reduce or increase contrail occurrence?
Does bypass ratio play a role?


texts: What is this part between the Su-35's jet exhaust nozzles?

texts:
What is the long thing that sticks out between the Su-35's jet exhaust nozzles and what does it do?

Source: 4ever.eu


texts: How useful would the space shuttle OMS actually be in atmosphere?

texts:
When speaking of space shuttle landings, they always mention that it is "very poor glider, with one shot, no go-arounds."

Of course this is true; however, if the Shuttle found itself in a situation where it was a little short on delta-v to reach land/a runway (perhaps during an RTLS abort), would the OMS make any meaningful difference in extending gliding distance?


texts: What is rotor damping and how does it affect helicopter stability?

texts:
What do we mean by rotor damping (in terms of helicopters)?
How is it affected by air density?
How does helicopter stability depend on rotor damping?


texts: I raised a question about this on this post in the comment section and was suggested by Peter Kämpf to create a new question. So here it goes: How does the extension of inboard flaps raise the effective critical angle of attack of the outer wing? And when that happens, why does the outer wing stall first without the help of slats when extension of the inboard flaps induces more lift on the whole wing, not just on the outer wing?


texts: What's wrong in this engine test cell picture from the book 'Ignition'?

texts:
This is picture taken from 'Ignition' book by John D Clarke.

I am bewildered after seeing picture that I can't find wrong in this picture. I guess this is related to the structure of mach diamonds.


texts: Was there ever an accident from in-flight smoking?

texts: In the 80s and 90s, regulation increased to prohibit smoking in passenger planes. Was smoking ever identified as the cause for serious accident in flight (for example the cabin caught fire as a result of a stray cigarette on the carpeting or seats)?


texts: How is the F-22's nacelle/engine bay ventilated?

texts:
How is the aircraft skin around the engine bay in the F-22 cooled?

As in the F-35, there are scoops below the wings, which provide ram air around the engine bay, but you don't see any scoop around in the F-22 for the same purpose.

Location of F-35 scoops according to codeonemagazine.com


texts:
Why isn't it possible to locate the rudder in front of an airplane's center of gravity?

Specifically how does this relate to the stability derivative?


texts: Why would a flight from Frankfurt to Madrid fly over London?

texts:
While enjoying the sunshine at the bank of the river Main in Frankfurt (Germany) this evening, I saw a LATAM B787-9 depart over the city center towards the north. This was slightly  surprising, as the only LATAM flight from Frankfurt is LAN705 to Madrid (Spain) (and then to Santigo, Chile) which is to the southwest. I have taken this flight quite a few times before and I don't remember it ever flew a northerly departure.

Even more surprising was that continued for a while to north, until I lost sight of it and had to take out the Flight Radar 24 App to track it. The flight continued towards the northwest, into the Netherlands and across the North Sea towards the UK.

By now I highly doubted the flight was going to Madrid. The only reason I could think of for this routing is that either LATAM changed their flight schedule and flies via another city to Chile or the aircraft was being ferried to Boeing in the US for maintenance (LATAM has many problems with the B789 Rolls Royce engines).

Coming back home, I just checked again where the flight was (fully expecting it to be mid-Atlantic) and I see this:

source: Flight Radar 24

source: Flight Aware

The flight departed Frankfurt, turn north, then northeast over Belgium and the Netherlands, into the UK. Then went over London, west-southwest over Lands-end, then over the Celtic sea it finally turns southbound toward Spain. It now entered Spain and seems to be heading to Madrid, but the flight will be over 2500 km, while a straight line between Frankfurt and Madrid airports is about 1420 km.

What is going on? What is the reason for flying over 2500 kilometers, while it could be only 1500?


texts: Why pets are allowed only on select flights?

texts: If the baggage compartment is always pressurized, why pets can be brought only to select flights and not all flights?


texts: Why is it 'aileron right and elevator up' with a front-right wind in a tailwheel airplane?

texts:
Question: How should the flight controls be held while taxiing a tailwheel airplane into a right quartering headwind?

Answer: When taxiing a tailwheel airplane into a right quartering headwind, use up aileron on the right hand wing and up elevator.

My answer: put the control to the right should be enough, why bother the elevator?


texts: What scientific evidence is there about the effectiveness of pre-flight walk-arounds?

texts:
As a student pilot, often on my walk-around, I get the impression that there are any number of hazards that could pass me by, simply because I can look at every part on the checklist but I wouldn't necessarily recognise a problem with that part. This idea seems more plausible when I speak to more experienced pilots of the same type, and each of them warns me about checking one thing in particular that's not on the checklist, because they once saw an accident that was caused by a failure there - and crucially, each of them warns me of a different thing.

At the same time, when I read the monthly accident report bulletins, there are several every month where the cause was some part failing in flight, and they either imply that the failure should have been caught in a pre-flight inspection, or they explain why it might not have been visible. In one local incident a few months ago, a pilot made a hard landing and thought he made an extra-careful inspection afterwards, but made a subsequent flight without noticing that both blades of the prop had been shortened and the firewall was crumpled. More generally, taking off with your pitot cover still in place is the stereotypical example of a bad inspection.

Pre-flight inspections seem very error-prone, on the face of it. What evidence is there about how error-prone they are, and what fraction of defects they detect? I'm asking for either scientific experiments under controlled conditions, or statistical analyses of aircraft grounded after unsatisfactory inspections vs. failures in flight. Turning the question around, you might instead answer about how much less safe we would be in GA or air transport if we didn't have pre-flight inspections at all. This related question is pretty relevant, but focuses on checklist items which are forgotten completely: I'm hoping for a more general answer which also includes defects that are not detected even if the checklist is performed correctly.


texts:
Order JO 7110.65T Section 6 Part 5-6-1 says

  Vector aircraft:
  a. In controlled airspace for separation, safety, noise abatement, operational advantage, confidence maneuver, or when a pilot requests. Allow aircraft operating on an RNAV route to remain on their own navigation to the extent possible.

What is a confidence maneuver?


texts: Could propellers benefit from the design of the Blue Edge rotor?

texts:
Source: wired.com

If indeed the Blue Edge blades reduce noise by 50%, could the similar design be used on [forward-facing] propellers without a penalty in speed or agility?


texts: What aircraft design elements contribute the most to sustained flight?

texts:
If I wanted to design an aircraft for autonomous operation and maximum endurance, what design philosophies provide the greatest benefit?  I'm imagining a powered glider.  Does not have to be highly maneuverable.

I'm interested in relative proportions, wingspan, length, center of gravity, center of pressure, wing placement, dihedral/anhedral, engine placement, fuel type, etc.

Is there a "sweet spot" for center of gravity relative to center of lift so as to maximize stability?
Since it will be mostly autonomous (computer-controlled), can I design for less inherent stability?
What engines/fuel types are the most efficient?


texts: What's the difference between hover power and maximum continuous power? Is a pilot clear to fly when its hover power is more than maximum continuous power calculated by table?


texts: Are there any aircraft that either fold or employ folding in their design (such as with origami)?

texts:
I became curious about origami and its application to aeroplanes and was wondering if there were aircraft that either fold and/or employ folding in their design in interesting ways.
Let's limit this to mechanisms requiring two or more creases/folds/axes/pivots that alter the geometry of something in a significant way. This should cut out most of the the obvious things e.g. fixtures (doors, food trays, landing gear and stair cases), control surfaces that act alone (canards, rudders, ailerons and flaps) etc. I wouldn't want to rule out any interesting applications however e.g. the use of leading and trailing edge flaps together (2 axes) or swept wings (2 pivots) is certainly acceptable. Finally, anything that is bizarre, curious or weirdly obvious is happily accepted !
Paper aeroplanes should be excluded unless there was some real world application thereof. Space stuff is also out.


texts: What do the regulatory bodies say about landing in CAT IIIB?

texts:
I typically read that CAT IIIB approaches must be flown by an autopilot to touchdown. Looking for a reference (regulatory bodies* in particular) to track the statement only leads to company SOPs.

In other words, with the runway in sight at or above the DH, is it written somewhere (excl. SOPs) that the pilot flying can/can't take manual control when the approach was started in CAT IIIB minima?

Full disclosure: I completely understand it's unwise and unsafe to even suggest hand flying an approach when that's the view:

RVR 200 m. (wikimedia.org)

* FAA, EASA, and ICAO, are acceptable (I couldn't find anything in ICAO Annex 6).


texts: How is the Flight Plan Data transferred into an aircraft/plane?

texts: I know that pilots have to fill the ICAO standard flight plan and send it to the relevant CAA to be checked, updated if needed and finally approved before the flight takes off. what I am looking for is to understand how does the  aircraft receives that acknowledged flight plan data. I know that some airlines receive the acknowledged flight plan from CAA's and then send it to the aircraft via ACARS so the aircraft, is this the most common option or there are other option for the aircraft to receive the acknowledged Flight Plan? Please let me know.


texts:
I was reading this article about EICAS:

  Engine-indicating and crew-alerting system (EICAS) includes
  instrumentation of various engine parameters, including for example
  revolutions per minute, temperature values, fuel flow and quantity,
  oil pressure etc. Typical other aircraft systems monitored by EICAS
  are for example hydraulic, pneumatic, electrical, deicing,
  environmental and control surface systems. EICAS has high connectivity
  & provides data acquisition and routing.(source: Wikipedia)

Wikipedia article doesn't explain EICAS functionality very well, specially on the matter of the Crew-alerting System.

I'm interested to know more about this system... So here is my questions:

I'm correct to assume that EICAS is a vital instrument for glass cockpits?
Is every fault displayed there? (ie. Radio failure, air packs malfunctioning, etc...)
What is the difference between red messages and yellow messages?
How much detail can a pilot get from its messages?


texts: How do I know when to read a number as (for example) 241 or 24.1 off the navigation computer?

texts:
How do I know in what way I should read a number off the naviagtion computer scale on the slide rule side?

Eg. 241 and 24.1


texts: What if the tower Is obstructed by clouds?

texts:
I know towers use radar to watch aircraft, obviously. But what about ground controllers? What if their view is obstructed by a low cloud level/fog?

Is there such a thing as ground-based traffic tracking? I’m not a pilot so bear with me if I sound naive.


texts: What is this on top of the Air Force One?

texts:
Clarification: It wasn't Air Force One that visited Switzerland, it was the 747-200 E4 carrying Ashton Carter. Source

What is this thing on top of the plane (In red circle):

On other "Air Force One" Google image searches, I can't find this thing. I know they have more than one 'doomsday-plane', but whats the purpose / use of this thing?


texts: Can anyone help me identify the plane in this photograph?

texts: I'd be very grateful for any help in identifying this U.S. plane. Other photos in the album look like they're from WW2.


texts:
I imagine some companies will fly banners or sky-write during the eclipse.
Do all need to submit a plan and get it approved by the FAA?

Could a company actually be allowed to block the eclipse "a little" for a big
festival?

EDIT: The answer here is not enough.  It doesn't even talk about filing a flight plan for a specific date.  So, are you saying any registered pilot (with the waiver to fly banners or to sky-write) could just wake up that morning and decide to advertise? That seems too easy and dangerous.


texts: Why do some A380 main wheels have no brakes?

texts:
The A380 has 20 main and 2 nose wheels. Apparently the nose wheels have no brakes (compare with Are there any aircraft with a nose wheel braking system?).

While researching for this question (How are brakes cooled on heavy aircraft?), I assumed that all of the 20 main wheels are braked. I looked at a few pictures of A380 landing gears. As far as I have seen, all main wheels are equipped with brake cooling fans (BCF), except the four rear wheels in the inner 6-wheeled  undercarriages. (e.g. here).

This picture below clearly shows that there is no brake unit inside the rim:

There is another picture here whithout BCFs, but the same four wheels apparently have no brakes.

What is the reason for omitting the brakes at these four wheel positions?

Is this a common configuration, or quite unique to the A380?


texts: Why don't all flights use the North Atlantic Tracks (NATs)?

texts:
I had assumed that all flights between western Europe and North America would use the North Atlantic Tracks (NATs) but this answer says that, actually, only about half do.  What reasons might a flight have for not using the tracks?

Wikipedia says that Concorde didn't use the tracks because it flew above them but I'd expect all commercial transatlantic flights these days to be within the band covered by the tracks (FL290–410).


texts: How are wing tanks sealed around the internal wing structure?

texts:
I can easily grasp the idea of tanks of fuel inside the fuselage of an aircraft, and the ease of sealing such tanks in a relatively standard shape.  However, I'm having a hard time understanding how wing tanks could be fit around the internal structure of a wing, as I envision the inside of a wing (especially nearer to the fuselage) to be a honeycomb of structural pieces that would be very difficult to seal around or find any large volumes of contiguous space for fitting tanks.  Is the wing structure itself the fuel tank, or are there separate fuel tank bladders that are somehow fit into the wing voids?

For my question, I am not concerned about military fuel tanks which might have special materials in the walls which could seal off a leak due to combat damage, but rather just non-military aircraft.


texts: Why is 51,000 ft a common service ceiling for business jets?

texts:
According to this article on aerospace-technology.com, many of the larger business jets seem to have a service ceiling of 51,000 feet. Other sources verify this trend.

What is the reason for this, if anything specific can be named? Some possibilities that I came up with are:

engineering considerations (limitations of materials, pressurization, systems capabilities etc.)
safety, i.e. time of usefull consciousness getting too short higher up (being less than 10 s @ 50,000ft)
too little to be gained going higher (no congestion anymore at that alt anyway)
an industry agreement (based on any of previous and/or other factors), in the same manner as european automakers' pact to limit the max speed of cars to 250km/h (excluding some model)
regulatory factors

Other common "steps" appear to be 45,000 ft and 41,000, with smaller models. Nice round numbers all, but surely there has to be some reason for the magical 51,000 ft figure. Interestingly, the Learjet 85 was designed to have a service ceiling of "only" 49,000 ft, and the program got cancelled at least partially due to poor sales. It seems it was simply lacking the last 2000 ft...

Examples of business jets with 51000ft service ceiling:

Cessna Citation X

Falcon 7X, 8X

Global  5000, 6000 and 7500

Gulfstream G550, G600, G650 ER

Learjet 40, 45, 60, 70/75

etc...


texts: What is this mysterious thing on the vertical stabilizer of the Boeing 707?

texts: Have you ever seen this mysterious line-shaped thing on the vertical stabilizer of a Boeing 707 or 720? What purpose does this thing do?


texts: How much thrust is available from the Allison T-56-A-15 engine?

texts:
What is the thrust availability per engine in Lockheed C130H?
The engines are Allison T-56-A-15 (SHP=4100, SFC=0.5)
Propellers = NP2000 eight Bladed(Prop Efficiency if assumed to be 90% constant at all speeds)
SHP - Shaft Horse Power


texts: If ELAC 1 is under MEL why is it a NO GO item when carrying out EDTO on the A320?

texts:
In the MEL for the A320 it is mentioned that ELAC 1 is a NO GO if carrying out EDTO operations. Why is ELAC 1 specifically for EDTO? In that case shouldn't it be for non EDTO operations also.

This somewhat contradicts ELAC 2 being a NO GO. Could someone please clarify this with an official reference.


texts: I read somewhere that Airbus developed the A350 in response to the B787. In general, how much do Boeing and Airbus know about each other's aircraft? And how do they learn about the detailed designs of those aircraft? Do they buy each other's planes and study them piece by piece?


texts: Is there any disadvantage to having the de-icing system on?

texts: I was watching Mayday S11E02 about West Caribbean airways flight 708 and the pilots turned off the de-icing system partway through the flight. It's not why it crashed, but I was curious as to if there was any disadvantage to having the de-icing system on.


texts: If engines are closer to the wing (or in the wing) does it increase efficiency

texts: If you were to make an engine in the wing or at least closer to it in commercial airliners such as the 747, 737 and A380 etc. Would it increase efficiency?


texts: Why, on carrier landings, does the Flight Path Marker (FPM) seem to be placed near to the end of the runway?

texts:
On most military aircraft landings, the FPM seems to be usually lined up with the start of the runway, either around the numbers or the aiming point, I would asume this to be the same on carriers for a higher probability of catching the wires, But it seems in most videos, the FPM is placed almost off the end of the runway.
Ex:

             (Loud noise)


texts: Does a large simulator bay have standard public address announcements?

texts:
We are simulating a "simulator bay" (with simulators) within a simulation and were wondering if there were any announcements made over the loudspeaker audible to people inside or outside the simulators.  Thinking of these large 5-simulator buildings like FlightSafety operates so anyone that spends a lot of time there (instructors, airline new-hires, someone headed there for recurrent training)... any help is appreciated. Thinking of things like:

Bay 5 is now available, bay 5 is now available
James Mahan, please report to bay 4 for your check-ride
Maintenance crew to bay 1, maintenance crew to bay 1


texts: Why are Jet Engine fan blades (and other turbomachinery blades) cantilevered rather than being connected together at their outer edges?

texts: It seems to me that connecting the outside edges of each blade together would create a stiffer structure with lower stresses and a better fatigue life for a given operating condition.


texts: In what ways is color blindness an issue in modern jet airliners?

texts:
What are the specific problems in modern jet airliner cockpits or in piloting operations that would prevent a person with any type or severity of color blindness from completing his/her job to the same degree as a pilot without color blindness?

As a follow up, are modern airliners designed to allow for pilots who have any type or severity of color blindness in case regulations change to allow them to work?


texts: Are the Boeing 747-8 engines more efficient than the 747-400 engines?

texts:
So I was doing some research on the Boeing 747-8/4 engines. I discovered that the PW4056/62 (747-400) has a much lower bypass ratio and weighs a lot less, and it is much smaller than the GEnx-2B67 (747-8). So it really seems the PW4084 is the more efficient engine. If it is not true than what improvements have been made on the  GEnx-2B67 to make it the more efficient engine? GEnx-2B67 engines

PW4056/62 engines


texts: Has there ever been an uncommanded lowering of landing gear?

texts:
Has there ever been an uncommanded lowering of the landing gear on a large commercial jet? I could not find any instance of it in a preliminary google search. Could a simple short-circuit cause such a thing?

I think this would actually be pretty bad at cruising conditions, because the airplane is going much faster up there, than on approach. But the air is also much thinner so I can't be sure.


texts: I am not aware of Class e3 airspace that is now associated in an area I used to be able to fly my ultralight, model airplane, or drone.  It is now apparently requiring FAA authorization.


texts: Why is the IFE only available after take-off and shut off before landing?

texts:
Every time I fly in an airplane that has an In-Flight Entertainment System (IFE) that consists of screens embedded in every passenger seat it is only turned on a few minutes after take-off and turned off a few minutes before landing? Why is this?

My limited knowledge of the system tells me that it should not interfere with any of the other on-board systems and thus it should not matter whether the system is running or not. The only reason I can think of is safety, similar to the question of why lights are dimmed during take-off and landing.


texts: Do modern aircraft have the functionality for the pilots to look behind the aircraft?

texts: Basically like the functionality of a rear-view mirror in a car. It's made known that pilots have all the information, hence they might not need the feature, but my question is to know if such a feature exists in modern commercial airlines.


texts: If an accident were to occur at a cross-border airport, who would investigate?

texts:
In the Wikipedia article Canada–United States border, there are several airports mentioned where the airport straddles the US-Canada border, in some cases the runway even being partially in the United States and partially in Canada.

If there was an accident at one of those airports, what agency would investigate the accident (i.e. the NTSB or the Canadian equivalent (the TSB?))

I'm specifically thinking of an accident that might have begun on one side (such as hitting the runway too hard on touchdown, or a botched approach), and led to something happening on the other side (such as an overrun, or a loss of control on the runway).


texts: I work as a paint shop prepper at an airport in the UK and have currently worked on a aileron of a 757-200 that was 14ft long and wanted to compare it to that of a A380


texts: Why aren't variable swept wings being used in newer military aircraft?

texts:
After finding out how well the variable swept wing design served the F-14, why hasn't it been used more often (outside of a select few)? Almost all of the fighters after the cold-war era haven't used variable swept wings.

Bonus question: is there any significance to the way the F22/F35 wings are shaped almost like triangles?


texts: What are the merits of an inlet cone/spike/centerbody vs. a 2D inlet?

texts:
And which is better for a scramjet?

Is a 2D inlet basically a "2D cone"? Similar to how an aerospike engine is made "2D" in the linear aerospike?

What's inside the cone/spike? Or is it just hollow?


texts: How much energy/prop efficiency does the e-volo copter sacrifice by having a smaller propeller?

texts: It seems like on an electric aircraft, it would be very important to have a high energy efficiency. Wouldn't the e-volo copter be much less efficient due to the small radius of the propellers when compared to a traditional helicopter?


texts: Are canards useful for ultra low flying aircraft?

texts:
In this question about canards, they are described as being useful mostly/only for supersonic configurations which are unstable at regular? speeds.

But for a low power, ground hugging aircraft, would a canard help create lift with less width?

This question is part of a human powered dream I have.


texts: How does the ADF null positions find where the NDB is?

texts:
I understand how it operates for the most part, although I don't understand how the null positioning works. This image below doesn't include the sense antenna that limits it to one null position, however how is the null position created? Wouldn't the signal still be received at that position, how does it become null?

Also does the null positioning tell you where the NDB is? If it's null wouldn't that mean no signal is being received so the beacon wouldn't be in that direction? Or do you find the null position, the assume it's 90 degrees from the beacon?


texts: Are centrifugal turbojets easier to make than axial ones?

texts:
Looking at the history of jet engines, I noticed that the British first made centrifugal-types, but the Germans went straight into axial-types.

Which type is easier, if any? By that I mean, which type is easier to design and produce? As far as I can tell, they appear to be very similar pieces of rotating machinery, just the compressor blades are shaped differently and the airflow follows a different path.

Are the equations of centrifugal flow somehow much more complex than axial flow, or vice versa? Are the shaft bearings of one much different than the other? Are there tougher geometric problems of lubrication with one but not the other?

Note that I am not asking which is more efficient or the better choice. That would have to take into account much more than the cost to design and build something. For now, I'm only asking about which type of engine is easier to build, if any.


texts: What does it mean to have a SIC limitation on your medical class 1

texts: Is there anyone who knows what a SIC limitation on your medical would mean? I found out on the EASA documents that it stands for "Specific medical examination pilot". But what exactly would a SIC change for someone (if anything).


texts: Does LSA hours count towards PPL training hours

texts: I hold a LSA license wit 200 hours. I am currently doing my PPL and I was wondering if any of the SLA hours can count for some of my PPL training hours? What are the regulations?


texts: How is accuracy achieved in Inertial Positioning?  Is it possible to get 10 or 11 digits of accuracy without transmission of real-time corrections from a base (known) station? Is post-processing simultaneous data of Ref. & Rover required for getting the precise (10 & 11 digit) coordinates?


texts: Why are helicopters less efficient than planes?

texts:
At higher speeds, advancing helicopter blades will operate at velocities approaching mach 1, reducing efficiency. But what about lower speeds?

A helicopter is basically a wingless plane with a giant propeller. Why is it more efficient to move around using propellers to provide forward trust while using separate fixed wings to provide lift?


texts: How is lateral CG managed in aircraft with uneven seating?

texts:
On many smaller jets seating is unbalanced with 1 seat on one side and 2 on the other side of the aisle.

Some examples are the Embraer ERJ-145:
Source - SeatGuru

Embraer ERJ-135:
Source - SeatGuru

And Saab 340B:
Source - SeatGuru

Assuming a full flight (where passengers cannot be moved to make balance shifts), how is the lateral balance/center of gravity maintained?


texts: If engine rotation was in reverse would it result in some kind of thrust reverser?

texts:
I mean if you rotated the propeller the other way would it result in reverse thrust.I wonder this because the propeller has to rotate in a certain direction to produce thrust, but would putting it in reverse cause a force to help stop the airplane?

And does this system exist with planes that have propellers?


texts: We have a number of questions here about E2 vs. E4 airspace (see summary of links in this answer) but what does that mean? As far as I can see, neither the AIM nor the ATC Orders mention E2 or E4 airspace, so what are they? What are the practical differences for pilots and controllers?


texts: What are the fins near the tail of a helicopter called?

texts:
My young sons are very enthusiastic about helicopters and I am repeatedly asked to name parts of their model aircraft. I would like to do so correctly, but my research has not always given definitive answers. I hope you can help.

Fixed to the tail boom and close to the tail rotor, some helicopters have a pair of horizontal fins. My research suggests these could be referred to as elevators, horizontal stabilisers, or horizontal fins. Is there one correct term, or does it depend on how they are used? Why do some helicopters not have them?

Most (all?) helicopters have a vertical fin connected to the tail boom. I have seen this labelled as a rudder or vertical fin. Does this depend on its function (moveable or fixed?) or can you suggest a better name?


texts: Does throttle control altitude and yoke control airspeed?

texts: I read that Throttle controls altitude and control wheel/ stick controls airspeed. Is that true? if so please explain.


texts: How does wing aspect ratio influence lift and drag?

texts:
I know simmilar questions are all over the internet (and this website too), but there's one thing that i just cannot comprehend and none of the articles i read could explain it properly.

According to wikipedia the coeficient of drag depends on the aspect ratio by the following way:
$$
C_D=C_{D0}+ \frac{(C_L)^2}{\pi e AR}
$$
But when i search why does it have this negative impact, i read things like "high AR creates stronger vortices at the tip of wings, which reduce lift".
But reducing lift reduces the numerator of the expression, so that should in fact REDUCE the drag. Does the $C_L$ somehow also depend on $AR$? If yes, is the dependancy also linear or less?

And another thing that blows my mind are statements, that wing which spans the  whole width of a wind tunel produces no induced drag, because it has no wing tips. Are you telling me that the induced drag is only caused by wing tips?
From the pictures at How complete is our understanding of lift? one would think that drag is natural part of lift and is caused by the airfoil even in 2D without considering wingtips.

So to sum up, can you please properly explain me:

How does the aspect ratio influence induced drag, why is the AR in
denominator
How does it influence lift
What really happens at the wing tips
What happens in the wind tunel on a wing that spans its
whole width


texts: Do reduction drives increase tach time quicker than direct drive engines?

texts: For example, the Rotax 912ULS engine has a 2.4:1 reduction. Does this mean that the Time Between Overhaul (TBO) will be reached 2.4x faster than in a direct drive engine or is tach time reduced by 2.4:1 as well?


texts: What are "referred" speeds and "referred TET"?

texts: i'm currently reading the Rolls Royce publication The Jet Engine. It makes reference to "referred speed", "referred TET" and "referred mass flow". Referred speed seems to be defined as N/sqrt(T). I guess that N is engine speed but I'm not clear on why it is divided by the root of temperature. Also can someone advise how referred mass flow and referred TET are defined please?


texts: What is a typical range of air temperature used for engine inlet cowl anti icing?

texts:
So i was searching the internet for engine inlet cowl anti icing and found that usually compressor bleed air is used to prevent the ice formation in several parts of the aircraft.
I am mainly interested in the inlet cowl anti icing section.
So the compressor bleed air is usually around 450 F ( correct me if i am wrong ).
I assume that this is not the temperature used for anti icing and before it is used for this purpose it is cooled down either because of the pressure difference or it passes through a heat exchanger or something else.
What is a typical range of air temperature used for the cowl anti icing and most importantly what is the lowest limit that is capable to prevent ice formation?
Thank you in advance.


texts: By placing a de laval nozzle at the inlet, can the resulting supersonic airflow allow a scram jet to operate efficiently?


texts: How much do aileron on a commercial airliner move for manoeuvring and trim?

texts:
I recently flew on an MD88 and had a good view of the aircraft's wing from my seat (read: I sat right next to the toilet). During the flight I noticed a couple odd things about the ailerons on the left wing. First, the middle one (there are three that I could see) was constantly pitched up by about an inch. Second, none of the ailerons seemed to move more than a couple millimeters during even the fastest banks (in fact, it was only that second aileron which I observed moving at all).

My questions are:

Was the second aileron being constantly pitched up for some reason? Or was it a trim issue?
How much do the ailerons even need to move to bank the aircraft? Would a couple millimeters do the job, or should I have seen more movement?

Edit: After taking some of the comments and searching around some more I found this diagram which seems to indicate what I was observing was not an aileron, but the outboard flap. Also this answer details why outboard ailerons are often locked in high-speed flight. But that still leaves the question of why the flap was constantly pitched up throughout the flight.


texts: Can a Boeing 767-200 fly at 510 knots at a height of 400 metres?

texts:
Can a Boeing 767-200 physically fly at 510 knots at around 400 metres altitude?

If it did manage that speed, how likely would a structure failure be?

Also, if those measurements were achieved, how difficult - relatively - would it be to control?


texts:
A "wet" takeoff of a KC-135 with J57 engines—By USAF Photographer (USAF photo) [Public domain], via Wikimedia Commons

Why is water-contaminated fuel bad, but water-injection is not?

The way I understand it, water-injection lowers the combustion temperature, which is good and bad, good for cool yet increased power-output / mass flow, bad for wasting [unburnt] fuel.

Why is then water dangerous when a trace amount of it is found in fuel? What's the worst that can happen apart from black exhaust and higher power?

Water-injection in jet engines and piston engines is mixed with fuel before it enters the combustion chamber, so I'm thinking fuel already mixed with water should not be any different. Of course I'm wrong. But why?


texts: How does blade solidity ratio relate to thrust/power/torque of a propeller?

texts:
for quite some time I was using ABBOTT formula for static thrust estimation on a two-bladed propellers:

$$
T=6.8\times10^{-5}\times D^{3}\times p\times RPM^{2}
$$

$T$ is Static Thrust (N); $D$ is propeller diameter (m), $p$ is propeller pitch (m); RPM (1/s)

I was, however, unable to find any formula which would include number of propeller blades.

Standard thrust estimation methods all seem to rely upon the "propeller disk area" which is always assumed for a two-bladed propellers.

The closest I was able to get is something called "blade solidity ratio", or "rotor solidity":

$$
\sigma = (B c)/2\pi R
$$

where $B$ is number of propeller blades, $c$ is chord of each blade, $R$ is radius of the rotor.

The question is - how does blade solidity relate to thrust/power/torque?


texts: What is this abandoned aircraft in Thailand?

texts: A friend found an old photo of himself and an abandoned aircraft in Thailand. Can you identify the aircraft?


texts: Can you help me to identify this helicopter?

texts: I came across this helicopter and am wondering what the oblong things on either side of the helicopter are, parallel to the front-back axis, offset from the main body.


texts: Does being cleared for a visual approach supersede speed instructions from ATC? (FAA)

texts:
Does being issued a visual approach clearance supersede speed instructions from ATC under FAA rules?

Here's an example. Let's assume an aircraft is being vectored for landing at a large class B airspace airport like KATL and has been instructed to maintain 210 knots. About 5 miles from the final approach fix on the ILS the aircraft is cleared for the visual approach. Does the visual approach clearance supersede the instruction to maintain 210 knots?

This is assuming the visual approach clearance didn't include an additional speed instruction along with it.

Please include the regulation or FAA-published guidance.


texts: How does the line of thrust affect longitudinal stability?

texts:
I’ve been studying Pilots Handbook of Aeronautical Knowledge FAA-H-8083-25B and on p 5-17 they talk about thrust line and stability. Can someone explain why the moment changes when thrust is applied?

  Power or thrust can also have a destabilizing effect in that an
  increase of power may tend to make the nose rise. The aircraft
  designer can offset this by establishing a “high thrust line” wherein
  the line of thrust passes above the CG. [Figures 5-26 and 5-27] In
  this case, as power or thrust is increased a moment is produced to
  counteract the down load on the tail. On the other hand, a very “low
  thrust line” would tend to add to the nose-up effect of the horizontal
  tail surface. Conclusion: with CG forward of the CL and with an aerodynamic tail-down force, the aircraft usually tries to return to a safe flying attitude.


texts: In this picture, shown in a recent news article, a "shooter" seems to be giving a "go forward" command to what I believe is a Lockheed-Martin F-35 aircraft already prepped in a VTOL configuration. But since VTOL's take off and land vertically, under what circumstances would a shooter give the pilot this "go forward" command?


texts: Can foreign pilots get a Canadian ATPL and work for a Canadian commercial airline?

texts: Can foreign pilots get a work permit for a Canadian commercial airline upon the completion of their training in Canada?


texts:
I know that similar questions are available all over the internet, including this website. However, none of the answers make full sense to me.

I'm looking for simple answer (explain-like-I-am-5 type of answer). The vertical stabiliser has rudder. It provides yaw capablity to the aircraft and I understand that completely. However, people say that if a vertical stabiliser doesn't exist, it's very hard to control the airplane, it rolls the plane out of control if not monitored.

As far as I know, the roll can be controlled using ailerons. I've heard that all wing plane design is not suggested because of lack of vertical stabiliser(s). What exactly is it that the vertical stabiliser does?


texts: Are there any low time lucky CPL holders who operate as PIC on medium or heavy jets?

texts:
CPL holder can be PIC on any plane if it's not a commercial air transport. So if the flight is positioning, acceptance, testing, delivery or any other without cargo and passengers any CPL holder provided he/she has TR and special training for the left seat can act as PIC? Do airlines allow this maybe as bonus for young first officers?
Another option is big business jets like 737 747 BBJ, A319...


texts: How close are planes allowed to fly next to each other?

texts:
I have a question - how close are planes allowed to fly when their paths are about to cross? I am sure there are proximity warnings and what not but I also know those accidents happen, even if not that often.

I was on board of a KLM flight from Amsterdam to Madrid and sometimes in the later part of the flight, if I recall correctly, another plane, flew just below us. Of course, I imagine human vision, mine included, is probably not the most reliable source. However, I saw the plane and in less than 1 second it speeded right below us, so I imagine that it was quite close. However, I felt no turbolence after it passed.

Given that description, can you let me know your thoughts - how close in reality it was? Of course if it helps, I can give you the flight number and day.


texts:
I know at larger airports, it's NEVER a slow time. But what about at smaller airports that are large enough to rate manned ATC, but things aren't always fast-paced, high-traffic like at JFK or DFW, etc. (say an airport like JLN (Joplin Regional))?

What other duties do ATC personnel do when the traffic is light? Do they just sit and stare all day at the readouts, waiting for any one aircraft to appear and call in? Or are there other "busy work" items they do when things are 'slow' and they are listening for air traffic to call in for instructions?


texts: Which version of the FAA's Instrument Procedures Handbook is current?

texts:
I'm looking for the current release of the FAA's Instrument Procedures Handbook. The FAA website for the IPH shows FAA-H-8083-16, but other FAA documentation I've found references FAA-H-8261-1A. I've looked for places to buy the Instrument Procedures Handbook such as Amazon and found that they're offering FAA-H-8261-1A.

Which one is current?

For future reference, how do I found the most recent release of an FAA publication?


texts: Is the whole world's airspace covered by ATC?

texts:
I'm an enthusiast and have only flown flight/atc simulators (on the VATSIM network). Obviously sometimes the airspace you are flying in is not covered by any ATC (so I have to set my frequency to Unicast). And very often there is only the tower of an airport available. How is it in the real world?

Is the whole world's airspace covered by ATC at all times?
Is any airport covered by all its layers of ATC (Delivery, Ground, Tower, ...) at all times?
How often do pilots use the Unicom frequency because there is no ATC available in current airspace?


texts: Why was "taxi into position and hold" changed to "line up and wait" in the USA?

texts: How come taxi into position and hold changed into "Line up and wait?" Did the old phraseology cause misunderstandings, or did it seem dated?


texts: Will dual-learning in a glider make my airplane learning safer?

texts: This question got me thinking, would attending gliding lessons at the same time as my airplane training make me safer in a small plane or microlight?


texts: What name is given to an abeam waypoint in the FMS?

texts:
In a Flight Management System, what name is given to an abeam waypoint in case of DIR TO?
Is this name format different in Thales and Honeywell FMS?


texts: Is it legal for a passenger to sit on the jump seat in Part 135 operations?

texts:
When operating a large turbine aircraft under 14 CFR 135, does the FAA allow a passenger to occupy the jump seat in the cockpit?

Falcon 900 jump seat

Would it matter whether or not they are a company employee (i.e. other than a flight crew member)?

Unlike the airlines, we usually fly with the cockpit door open (if there is even one installed) so it isn't a security issue like the airlines.


texts: How is the term "Coast" defined for FAA regulatory purposes?

texts:
14 CFR 91.1 defines the applicability of part 91. This paragraph defines two areas of jurisdiction where certain parts of part 91 apply:

within the United States, including the waters within 3 nautical miles of the U.S. coast
the airspace overlying the waters between 3 and 12 nautical miles from the coast of the United States

By exclusion the third area is the airspace overlying waters beyond 12 nautical miles from the coast of the Unites States. Part 91 therefore does not apply in this area. The FAA explicitly states this in letters of interpretation, for example, in Di Marco (2008).
The term "coast" appears to be undefined in any readily available FAA resources.
How are we to understand this term as applied to the scope of applicability of §91? For example, would a shore of one of the Great Lakes—Lake Huron for example—be considered a "coast" for this purpose? To apply the question more specifically, would a pilot be required to comply with the 250 knot rule of §91.117 if below 10,000 ft while 15 miles off the US shore over Lake Huron.


texts: What are the advantages and disadvantages of mixing the bypass flow with the core flow?

texts:
Many Aircraft engines mix the bypass air with the core gases before exhausting to atmospheric pressure through a propelling nozzle. However, some do not mix and have separate nozzles for the flow of each. What are the advantages and disadvantages of each?

PS: I hope that I am clear now. Sorry if the question wasn't clear earlier.


texts: How are wind tunnels used with scale models?

texts:
This answer introduced me to the problem of using scaled models in a wind tunnel.

How are wind-tunnels used in practice (for modelling the performance of subsonic airplanes)? In particular:

Do they used increased air pressure, or another mechanism, to compensate the Reynolds number?
What scale model is used? A scale of e.g. 70:1 appears to be difficult, because you can't pressurize air that much before it liquifies. So do they use a scale like 10:1? More or less?
What are the forces (lift and drag) generated on the model? The weight (therefore the lift) of an A380 is about 500 tons. Apparently the lift on a 10:1 scale model would be 50 tons. Is that real? Are they making 10:1 models which cope with 50-ton forces?
This picture (from Wikipedia's Wind Tunnel article) shows what seems to me to be a 10:1 scale model of a supersonic plane in a subsonic tunnel. The tunnel doesn't seem to me to be built to handle multi-ton forces. What kind of air-speed will they be using, what would they be measuring with that kind of test?


texts: If the modern airliner was redesigned from scratch, would it look functionally different?

texts: If the modern airliner (Boeing/Airbus) was redesigned from scratch today without any need for "backward compatibility", would it look functionally different from the current design? And if so, what would be different?


texts:
Pax in commercial transport is used as something like persons or passengers, in the context of counting people, e.g. 150 pax onboard.

(Amadeus capture, source)

I observed that in German writers tend to use the meaning:

  PAX = Persons approximately.
  (Source: European Union and the Committee of the Regions)

English.SE has a page for What does “pax” mean in the context of the apartment rental? Selected answer:

  Pax isn't exactly shorthand for Passengers. It's short for
  Passengers and Passes.

But the author of the answer agreed that another answer was likely more accurate. The latter has a reference to a magazine, Air Facts: The Magazine for Pilots - 1946:

  Cargo is known as "cargo", but passengers are called "pax" by the
  traffic department, who puts them on and takes them off the airplane
  and "bodies" by the crews who fly them.

Pax could be from passenger as usually assumed in the Aviation community, albeit I don't see why not *pass" instead. I wouldn't be surprised it comes from the merchant navy.

Can we track the use further back to the origin in aviation field?


texts: What are the meanings of those SFO Taxiway Marking?

texts:
I'm studying aviation and pulled up a Google Map satellite view of San Francisco International Airport (KSFO) and was wondering if someone could shed some light on what a few of the taxiway markings meant.

What do the straight lines starting from the taxiway edge marking towards the "median" area mean? Probably that it's not usable for aircraft taxiing - but I couldn't find out what the name of these lines were.
What is the number inside the small pink / purple used for?
What are the white numbers inside the blue boxes used for?


texts:
I Am asking about the takeoff power here not how the aircraft takes off.

What do I need if I want to calculate the power required by an aircraft to take off?

What parameters should I consider?


texts: How come the hover efficiency for tiltrotors is better than tiltwings?

texts:
How do you compare the hover efficiency of tilt-rotor and tilt-wing aircraft? The Wikipedia page Tiltrotor mentions:

Tiltrotors generally have better hover efficiency than tiltwings (...)

But I was expecting just the opposite because of the downward thrust loss due to wing blockage on tilt-rotors.


texts: Are there any "alternative" passenger airline business models?

texts:
(By passenger airline in this question I mean scheduled carriers, with at minimum a few aircraft with 50+ seats.)

I am aware of 3 main classes of airlines:

Hub-and-spoke (most major airlines)
Low-cost carriers (Southwest, Ryanair)
Regional (contractors that support more "spokes" for the majors)

Are there more? If so, where and how are they used?

Note: I accepted the answer that shows a clear example, but there are many other excellent answers below!


texts:
How do Alaskan bush pilots land and take off in 10'?

Just looked at a video of the Valdeez STOL competition with pilot's taking off and landing in 10'

How do they do it? And no, they don't have a headwind of 40mph. Headwind is usually 10-15mph which is a pretty common scenario for all of us.


texts: Is it legal for a balloon to land at a US international airport?

texts: Assuming the winds directed a hot air balloon near a US international airport, and the pilot has no other choice than landing, say near the runways/taxiways, would they face legal trouble/fines?


texts: What is the highest operational ceiling for an air-breathing jet engine?

texts:
An air-breathing jet engine can only operate at relatively low altitude, where the atmosphere is dense enough. However, some jet-powered aircraft can operate at an altitude higher than 20 Km (e.g., the SR-71). For really high altitude, aircraft are equipped with rocket engines (e.g., the X-15)

What is the highest operational altitude for any air-breathing jet-powered aircraft?


texts: Where is the F-4 Phantom II's flap lever?

texts: I'm trying to fly this fighter for the first time in X-Plane 11 but I can't seem to find the flap lever in the cockpit. Where is it on the real plane?


texts: Why didn't Philippine Airlines Flight 113 dump fuel prior to forced landing?

texts:
Philippine Airlines Flight 113 operated by a Boeing 777 bound for Manila suffered a compressor stall and engine fire.

I wonder why the pilot didn't dump fuel from the left-side prior to the landing to meet the maximum landing mass (MLM) required and to avoid damaging the undercarriage as seen in pictures?

I assume that, when I have an engine fire, I shut it down and crank the remaining fuel residual until it is put out. Any idea?


texts: Why has the Bombardier CSeries been delayed in starting service with Delta Air Lines?

texts:
Delta Air Lines placed a large order for the Bombardier CSeries. I don't know the original projected date for the start of CSeries flying, but I think it already passed.

When is DAL planning to start CSeries flying? What is the reason for the delay? Have any problems with the aircraft itself caused the delay?


texts: How do you determine how much "life" an aircraft has left?

texts:
I am looking to purchase an aircraft, and I've found one described as follows

  Total time is 6300 hours
  Engine time since major overhaul 2100 hours
  Engine runs strong and compression is all in the 70s
  Has VAL Avionics all-in-one VOR/LOC/GS unit

The owner also states that the engine was rebuilt 556 hours ago, but this was never entered in the log books, so we're working based on 2100 hours since overhaul.

We have done a pre-buy inspection through A&P mechanic. On the report was mentioned,

  TACH TIME ;8131.18
  HOBBS ;  7141.9

Can you explain for me what these time figures mean and how I can judge the remaining life left for this engine and airframe?


texts: Why is there no Maltese Cross in this non-precision approach chart which has a FAF?

texts:
I am wondering why this chart does not show the FAF with a maltese cross as it is used in non-precision approaches to depict FAF.
The chart’s briefing strip refers to D6.0 as the FAF and on the plan view FD23 code can be seen(which also indicates that this the FAF).


texts: what kind of Processors and GPU are used for Aircraft display ? Is it possible to use single processor to run all three displays (Primary flight display, Navigation display and EICAS)?


texts:
While reading some articles about free route airspaces I found reference to two types of waypoints:

  Free route airspace (FRA) is a specified airspace within which users
  can freely plan a route between a defined entry point and a defined
  exit point, with the possibility of routeing via intermediate
  (published or unpublished) waypoints ...

My question is the following: What is the difference between published and unpublished waypoints? How are they created? When are they used?

Could you please provide me documentation/citations as well in order to have a complete overview of the topic?


texts: What causes the ball to not be centered in a slip/skid?

texts:
I've reviewed quite a few questions on this forum including
Forces in a slipping turn
is-this-vector-diagram-of-the-forces-at-play-in-turning-flight-correct
what-does-the-balance-ball-actually-indicate
but I don't believe they have answered this specific question.


texts:
If I own a helicopter and am appropriately rated, can I land the helicopter anywhere that isn't private property, and is a safe place to land (clear of obstructions, appropriate surface, etc.)?

My question is specifically about the regulatory requirements to land a helicopter off-airport in the United States.


texts: Why do piston engines in aircraft burn fuel at a higher rate than a comparable car engine?

texts:
I've never understood why piston powered plane engines burn such a large  amount of fuel per time period than car engines.

Can anyone elaborate on this?

I know that a C172M will burn ~5-9+ gph at 2200-2550 RPM between 2k-12k feet based on the POH.  This gives a decent idea of the fuel burn in a very narrow RPM range at various altitudes.  According to the POH, she came with a Lycoming 0-320-E2D. Wikipedia states that the 0-320 provides 150-160HP using a 5.23l engine.

My car on the other hand has a 2l 4 cylinder engine. At 70mph in top gear @ ~2300rpm she gets about 30mpg for a calculated 2.33gph. To me highway speeds at constant RPM provides comparable engine conditions to that of cruise phase of flight.

5.23l / 2l = 2.61

2.61* 2.33mpg = ~6gph

Does that basic analysis hold? Is the larger displacement the main factor in fuel consumption difference between the two? I consider this figure of ~6gph close enough to the 5-10gph listed in the POH for such a back of the napkin calculation if the analysis is more or less correct.

This leads to a follow up question: Is there a reason for the large displacement and low HP? For comparison a 5.7l truck engine from the 70s output 250HP for a gain of 100HP for .47l additional displacement when compared to the Lycoming. I'm in no way very knowledgeable about engine's but am guessing the answer lies in engineering trade offs for making the engine lighter or out of a different material for aviation use or for higher compression ratios for the fuel. Any detailed input would be appreciated.

I know that Volkswagen and Subaru engines have been used for aircraft.  Although my research has been very light, it still looks like the fuel consumption is in the same range.

Going back to my car vs the C172M, or the EcoTec vs Lycoming, 173hp@ 5500rpm for the EcoTec and assuming a (most probably false) linear fuel consumption based on RPM,

5500rpm /2300rpm = 2.39

2.39 * 2.33gph (@2300rpm) = 5.56gph

for comparable HP.

If my analysis provided here is close to the true answer, then I think I've cleared up my misunderstanding by writing out this question.  However, I would like someone more knoowledgeable about such things (possibly an A&P who is also a gearhead) to pipe in and verify or enlighten my analysis.

Thanks!


texts: What is the best time to run runway friction tests?

texts:
When is the best time to run runway friction tests?
And what is the optimum temperature to run them?


texts: Can you be a pilot after being diagnosed with Generalized Anxiety Disorder?

texts:
Went to my primary care physician who referred me to the psychologist. Went in for two evaluations. The only thing that had been written on my medical record was anxiety, no medications of any sort had been prescribed and the psychologist asked that I enrolled in anxiety classes in college (this was during my freshman year) I am a sophomore now.

Was wondering if this diagnosis of anxiety could prevent me from obtaining a third class medical, although it is not listed as anything that requires an FAA decision especially if no medication has been taken or prescribed.


texts: How far can one be from an helipad when marshalling an helicopter?

texts: I considered 25 meters (as per UN SOP's) but after working years with MI-8's the downwash can flatten a big man. I'm interested in procedures from the FAA etc. ...


texts:
The direct cause of stall is unclear to me.

I heard about exceeding maximum angle of attack (around 40°) ;
I heard about reaching the stall speed in the current configuration (flaps, etc).
I heard about load factor which can lead to a stall.

Are these three parameters both direct causes of stall? By "direct", I mean for example that pitch is not a direct cause to stall, since pitch let AoA vary which causes stall.

It's unclear because there is a relation between angle of attack and speed. When we increase the angle of attack, we lower speed. But at the end, what will be the cause of stall?

If both causes are direct causes, are they independent?
- It should be possible to fly very fast (faster than stall speed) and have an angle of attack of 40°.
- It should also possible to have a very low speed (lower than stall speed) and have an angle of attack which produces lift.

What parameter will win and how are they related together?

When an aircraft is on the ground, taxiing at 10kt, the speed alone makes the plane stall, regardless of the angle of attack, am I right?

I would like to know necessary conditions to stall, and sufficient conditions to stall (all conditions being direct causes).


texts: Why does this Garmin GMA340 have an Airway/Inner marker indicator?

texts:
On this Garmin GMA 340:

the outer marker is blue and is designated O
the middle mark is amber and is designated M
the inner marker is white and is designated A and placed on the far left.

I looked at the GMA 340 Manual and could not find an answer although it does say Airway/Inner Marker.

Why would it say Airway if this is what the A indeed stands for and why even have an inner marker because that Garmin can't do a Category II approach?


texts: How can I correctly calculate fuel for a Cessna 152?

texts:
I'm learning to fly in a C152 and I've found the fuel calculation to be a little ambiguous. Based on information from my instructor, Internet and the Cessna 152 Information Manual (1980), I've home cooked the following formula and wanted to run it by the community for some verification.

I hope this is an appropriate use of this forum and please excuse my newb-ness. Here's my formula:

Fuel Required =
    5.6L unusable +
    5L run-up and taxi +
    24L/hour flight (rich) +
    18L (45 minute) reserve

Based on this formula, a one hour lesson conducted in the training area and below 3,000 feet AMSL requires a minimum of 52.6 litres in the tanks, calculated as follows:

5.6L unusable + 5L run-up & taxi + 24L flight + 18L reserve = 52.6L total

Or 26.3L in each tank. Since we're measuring fuel by the surprising method of dipping a stick in the tank, I'm realistically looking for around 25L per tank, and maybe topping it up to 30 per tank to be on the safe side.

Is this correct and reasonable?


texts: How was the high-bypass concept invented?

texts:
(Source)

Wikipedia says:

  After [the Ryan XV-5 Vertifan demonstrated] that large amounts of air could be moved through a lift fan, an 80 in (2.0 m) tip drive fan turned through 90 degrees, driven by a more powerful J79 engine, was built to demonstrate an efficient cruise fan. The concept of a large diameter cruise fan was incorporated in the General Electric TF39 engine, used on the Lockheed C-5 Galaxy.

Was the XV-5 responsible for ushering in the high-bypass concept?

The economic drive is discussed here:

What drives and/or allows the move to higher-bypass turbofans on jetliners?

I'm more after the evolution of the engineering concept I think, i.e., the different iterations and studies—a brief history lesson.


texts: Do most commercial jets have a negative lifting body?

texts:
I took a look at some example airfoils and noticed they all seem to have a downward hook at the end. I believe this draws the air downwards, creating a reaction force upwards: lift.

Now here is a typical wide-body jet profile:

Notice how the fuselage points upwards at the tail. I'm not talking about the vertical stabilizer, not the horizontal stabilizers either. I'm talking about the fuselage getting narrower and narrow at the tail. It tapers to a point, but the taper flows upwards.

I'm sure this shape has to do with avoiding tail strikes. But is seems to me like it also incurs negative lift. Does the tail draw air upwards, creating a reaction force in the downwards direction and thus negative lift?


texts: Why does a hovercraft lift blade look one way, but a propeller another?

texts:
The lift blade of a hovercraft looks like this:

Note the ten rectangular blades.

The blade of a propeller-craft looks this this:

Note the three, traditional airfoil-shaped blades.

Why are the two different?

Edit: My question is different from the other question cited because it asks about both the number of blades and their shape, as well as other differences I may as of yet be unaware of.


texts: What are the major causes of parachutes failing to work?

texts:
What are the top causes of a parachute failing to work?

For "parachute", I mean primarily sporting parachutes, such as used in skydiving, but information about military (paratroop) chutes, ejector seat chutes, etc., would be useful.

For "failing to work", I mean "fails to prevent the sudden stop at the bottom", whether this is through failing to deploy properly, getting tangled, structural failure or whatever.

Inspired by the following comment on this answer:

  maybe you could add something about why sometimes chutes don't open. –  rbp


texts: Whats the effect of aerofoil camber and thickness on Clmax and Cdmin?

texts: Does anyone have any experimental references/wind tunnel testing testing data for various thickness and/or camber?