texts: What's the preferred approach for a passenger jet?

texts:
I seemingly can't find an answer to this quite obvious question:
What's the preferred approach procedure for a passenger jet at a modern airport fully equipped for precision ILS (both aircraft and airport): ILS or visual approach?

If it's ILS, what would cause a visual approach to be flown (except for the ILS not working of course)?

If it's visual,

a. why? (ILS seems more secure from my naive standpoint)
b. what would be the cause to do ILS instead? Bad weather / sight for instance?

Is the decision made only by the tower or does the captain of the aircraft have any saying in it?


texts: How to interpret the electrical information on a G1000 T206H?

texts:
I have a T206H and The POH says:

  Current indication (AMPS) for both the main and standby batteries is
  provided at the bottom of the EIS bar (along the left margin of the
  MFD or PFD), labeled M BATT S. Main battery current is numerically
  displayed below the M. Main battery current greater than -1.5 amps is
  shown in white. Standby battery current is displayed numerically below
  the S. A positive current value (shown in white) indicates that the
  battery is charging. A negative current value (shown in amber)
  indicates that the battery is discharging. In the event the alternator
  is not functioning or the electrical load exceeds the output of the
  alternator, the main battery ammeter indicates the main battery
  discharge rate.

The part that confuses me is the one that says:

  Main battery current greater than -1.5 amps is shown in white.

Does that means that when the number is negative but greater than -1.5 it is OK, because it is in white?

And after 40 minutes of flight in normal daytime operations I have a -1.0 in the M BATT amps but the M BUS volts remain 28.3. What does this mean?


texts: Why are westbound transatlantic routes located hundreds of km away from eastbound routes?

texts:
Are jet streams a net benefit in time and fuel savings? provides (basic) explanations about jet streams in the Pacific. However I'm looking for an answer focused on North Atlantic area, explaining the track system and the tracks location. In addition BA 185 route seems to be composed of two arcs, did they change their mind in flight because of the wind? or is this related to ETOPS or alternate airport at Santa Maria?

Looking at flights between NY and London (click to see route):

BA 185 (EGLL - KEWR)
United 941 (EGLL - KEWR)
United 16 (KEWR - EGLL)

The FlightAware anticipated routes are quite similar in both directions, but the actual routes for past flights are really remote from each other:

The two westbound routes are either 800 km north or 1,000 km south of the eastbound route (the dotted line shows the shortest path).

Why are the two westbound routes different and so remote from each other? Why this difference of about 1,800 km?
Why BA 185 route seems to be composed of two arcs?
Did the pilots changed their mind in flight because of the jet streams? Is it related to ETOPS constraints, or alternate airport at Santa Maria? or something else?


texts: What is this thing between the engines on the F-14 Tomcat?

texts: On the F-14 as you can see from a picture there is some exhaust like thing in between engines. What is this?


texts: What are the limitations on a steep approach?

texts: Certain aircraft like the A318 are able to do steep approaches for landing. What are the limits (Angle of descent, airspeed, and the like) for this type of landing?


texts: Why shouldn't the pilot change the aircraft's configuration while avoiding windshear during landing?

texts: According to the procedures, when going around, due to windshear, pilots shouldn't change the aircraft's configuration, such as flaps position and landing gear extension. If changing, would the aircraft lose the lift? why?


texts: Cp, Cg and Np location of a tandem wing configuration, both have positive lift?

texts:
I understand that in a tandem layout( 1 wing at front of plane, 1 wing at rear, both have positive lift) , the Cp has to be ahead of the Cg, and the Np behind the Cg.

Is there a rule of thumb how far forward the Cp has to be in front of Cg?, like 17% to 33% of MAC, etc.

Should Cm vs alpha, still have a negative slope?

Is it possible to have a 50% lift split between rear and front wings, just have a higher incidence in front wing, so it stalls first.

Any help would be appreciated


texts: Is it legal for a non-IFR rated pilot to fly a SID on a VFR flight?

texts: Just wondering in case the pilot is unfamiliar with the airport / terrain or is flying at night and wants obstacle / terrain separation.


texts:
Can anybody enlighten me on the nature and physics behind what is referred to as Shock on Shock heating. Both , "Hypersonic: The Story of the North American X-15 , Jenkins and Landis" and "Lessons Learned from the X-43 Program published by AIAA", refer to this effect.

The static temperature jump though a shock is well described but this Shock on Shock heating seems to be an effect greater than the sum of it parts.
Both sources refer to flow within the Hypersonic regime.

thanks


texts: I was flying under class bravo airspace at 1800 feet which was the legal altitude 1800 and below but my transponder is off by 200 feet so they thought I was 2000. when I landed and i had to talk to the tower. He did not say anything except be careful and turn your altimeter down next time and be careful. nothing else happened but am I OK? did the get my n number ? i never gave them my name or info.


texts:
Is MIL-PRF-5606 H flammable at 350 deg C?
Is it a flammable or combustible hyd oil?


texts:
A photo in EAA's monthly magazine shows one propeller blade as a dozen distinct images rather than the usual smooth motion blur.  One explanation (this answer appears to have been deleted) for this is that a propeller at nominally 2300 rpm actually varies +-200 rpm as each cylinder fires, so when it's slower, it captures more sunlight glint.
Edit: this question is about propellers, not about a photo.  The photo is only a motivation, perhaps an incorrect one, for the question.
Is this plausible?

Piston engines have flywheels.
A 400 rpm change happening 2300 times per minute is a 17% change happening 38 times per second.  Jerry Lee Lewis would say that's a whole lotta shakin' goin' on.
Onboard GoPro videos with rolling shutter artifacts show the blades "bending" from root to tip smoothly, not jaggedly.


texts:
How to determine individual wing loading of a triplane for stress analysis?

I understand that a monoplane must be able to withstand the weight of a plane x a load factor, say n=4, for a standard flight envelope, and also asymetrical loading.

What about triplanes?

Should each wing carry 1/3 the load?

Assuming 1 deg decalage each for the 2nd and 3rd top wings, they will stall before the bottom wing.

But.... you could have a situation where the top wing is stalled and the bottom 2 wings see the full load of the plane

And... you could have a situation where the top 2 wings are stalled, and the bottom wing is subjected to the entire weight of the plane.

So.... how strong do you have to make each wing of a triplane?
Of course, if the plane has struts, all 3 wings would be part of the equation.

My gut feeling is that the top wing should be 33% loading, middle wing 50% loading, and bottom wing 100% loading, and then model the wings as 3 joined cantilevered beams.

Is this correct?


texts: Do 'threshold' and 'end of the runway' mean the same thing?

texts:
While I studied aviation, I got confused by these two words.
Can anybody explain whether they're the same or not, and if not, what is the difference?


texts: Do elevators have cambered airfoils inverted or symmetrical airfoils

texts: Do horizontal stabilizer of ga planes e.g cessna 172(or ultralights e.g lazair) have cambered airfoils inverted to provide the tail downward force or do they have symmetrical airfoils at negative aoi to provide the downward tailforce during flight.


texts: Is it possible to maintain horizontal flight with the angle of attack above critical value by increasing speed?

texts:
In this video a stall happens at 1:40 upon reaching the critical angle of attack. The air flow is now detached from the upper part of the wing, resulting in higher pressure above the upper part of the wing, thus eliminating the major factor of lift.

Let's imagine that we have extremely powerful engines and enough tail stabilizer authority to maintain horizontal flight with any speed.

Is it possible to maintain horizontal flight when:

wings have high angle of incidence (let's assume some experimental design)*
aircraft has zero pitch condition (straight and level flight)
permanent state of high angle of attack (as the consequence of the 1 and 2)

*high angle of incidence is an angle between wing chord and longitudinal axis of the plane (fuselage)

I assume, the lift that we will get in this case, will be generated mostly by Newton's law by deflecting air ONLY by the LOWER side of the wing.


texts: I have a document referring to aircraft with maximum takeoff weight of 45000T. Is this an error?

texts:
I got the attached document from http://www.aisthai.aviation.go.th/.

This document refers to aircraft with MTOW 45000T.

Is that 45000 tons? That's pretty heavy for me. Or am I interpreting the document incorrectly?


texts: How close is an obstruction allowed to be in an instrument approach?

texts:
Inspired by this answer, and the comments that followed.

City politics aside, i.e. hypothetically, can KBOS rwy 14 be used for landing aircraft that don't comfortably need more than 5,000 feet of runway?

The issue arises from the building at the approach end of rwy 14.

The building is 174 ft. tall, lighted, 1364 ft. from runway, and 70 ft. left of center line.

The RPZ (protected zone for excursions) by FAA standards is 1000 ft., which the runway meets.

FAA also says the OFZ (Obstacle Free Zone, the 3D area covering the approach end) would only be 200 ft. since there is no Approach Lighting System installed.

In summary, imagine the building is a rocky outcrop somewhere in a desert, and someone built a 5000-foot runway the same distance from it as KBOS 14, can it be legally used?

Visually I don't see why not, but I'm not an FAA administrator. And for an instrument approach I also don't see a problem stepping down to a specified MDA, and even at an angle (LDA).

To raise the stakes a bit, I believe a DC-9 can comfortably land on a 5000-foot runway. Let's use a DC-9 or similar type in the example above.

To make the answer less stressful, if you know of a similar airport/obstacle scenario, or can find one, with a published approach, let us know.


texts: How to use Rudder during takeoff in single engine propeller aircraft? e.g. Cessna 172

texts:
Background: I am a complete beginner on Flight Simulator X: Steam edition, using a simulator setup with rudder pedals with realism set to the max (to simulate more realistic flying).

I understand that rudder use is essential to align the aircraft to the runway centreline during takeoff due to the left turning tendencies. However, I cannot seem to consistently align the aircraft to the runway centreline during takeoff. Sometimes, I just run parallel to the centreline.

Questions:

Is this common in real life flying? Are actual pilots consistently able to align the nose wheel to the runway centreline during takeoff in such single engine propeller plane or am I being too idealistic?
How is the operation of rudders in an actual aircraft like? Slow smooth gentle depression e.g. to the right pedal each time the aircraft swerve to the left or are the left and right legs constantly moving in quick succession to keep the aircraft aligned to the runway centreline?
Generally, how much of a push is required on the pedals during takeoff? It seems to be very very slight 1cm touches to my rudder pedal on the simulator. Is that realistic?

Thanks so much everyone! All answers are appreciated!


texts: Why does the F-117 Nighthawk look different than other stealth planes?

texts:
The F-117 Nighthawk has flat angled lines where most later designs (B2, F22, F35) have very smooth lines. Why the difference? Are the newer designs 'more stealth'? Do they use a different design to handle better? Is there another reason the distinct angled look is avoided in later designs?

The question, 'Why do many stealth aircraft have a similar shape and design?', is close, but doesn't really address why the F-117 stands out from the rest.

Left: F-117, right: F-22.


texts: Are there regulations for the field of view from cockpits?

texts:
Are there any design or ergonomic regulations with regard to the pilot's vertical and horizontal vision angles from the cockpit?

For example, pilot should see space 30 deg. above and 20 deg. below horizontal.


texts: What is the incidence angle of a propeller in the terminology of the Wright Brothers and how did they obtain it?

texts:
What is the angle of incidence of a propeller in the terminology of the Wright Brothers and how did they obtain it?

In Feb. 1903 (see Screw Test 1903, page 8), using a 0.58 hp engine, the Wright brothers tested a propeller characterized by:

Diameter, D = 8.5 ft

Pitch = 15 deg

Surface, $S = 2\ ft^2$

RPM = 245

They measured what appears to be the static thrust and got:

Thrust = 18.75 lbf

Based on the assumption that the propeller can be modeled by a wing (Pitch = 15 deg, Surface = $2\ ft^2$, Lift = 18.75 lbf) having its entire area concentrated in a single point (called  the Center of Pressure, C.P.) traveling at RPM = 245 on a circle with the diameter 0.824 x D, $V_{wing} = RPM \times \pi \times 0.824 \times D$, the Wright brothers evaluated its Drag and from Lift, Drag and Pitch using trigonometric relations they obtained the Normal (perpendicular to the chord) and Axial or Tangential (along the chord) components of Lift + Drag (the resultant force) and some angles related to them.

Now comes something I do not quite understand.

The two brothers calculated a reference force defined as:

Total Normal = $k \times S \times V_{wing}^2$ = 24.8 lbf,

where

$V_{wing} = RPM \times \pi \times 0.824 \times D = 61\ \mathrm{mph}$

$k =$ Smeaton’s coefficient $= 0.0033\ \mathrm{lbf} \cdot \mathrm{ft}^{-2} \cdot \mathrm{mph}^{-2}$

Further, the Wrights divided the Lift by the Total Normal

$\frac{\mathrm{Lift}}{\mathrm{Total\ Normal}} = 0.756$

and from this 0.756 they drew the conclusion that the angle of incidence is 7¼ deg. The question is why? What is this angle of incidence and how can it be calculated?

Update

The correspondence between the percentage 0.756 and the angle of incidence, 7¼, comes likely from a table like this (which is for a slightly different wing curvature):

Percentage of air pressure at various angles of incidence

However, as the propeller did not move, the incidence angle of its equivalent wing appears to be identical with the pitch of the same wing and they are not. Why?


texts: How to land the aircraft when the flight deck is full of smoke?

texts:
If a fire occurs in flight, the crew will likely try to land on a diversion airport. However landing presupposes seeing the primary instruments, switches and controls.

Source

In case the fire is not extinguished in time, how would the crew manage smoke in the flight deck to be able to land safely.


texts: Is sustained inverted flight possible with any of today's commercial jet aircraft?

texts: After viewing the movie " Flight", I was wondering if extended inverted flight was possible with any of the current larger commercial jet aircraft?


texts: What is the accepted ADS-B quality indicator value from EASA/FAA?

texts:
I'm doing research that has to do with the ADS-B quality indicators. With the ADS-B quality indicators I've received, I want to compare them with EASA's or FAA's requirements for each ADS-B Version (260, 260A, 260B) and see if they have been met.
I am having trouble finding the right document that tells me the minimum requirement. The quality indicators I've received are NIC, NACp, NACv, SIL, GVA, and SDA. At the end, I want to show the statistics of how many actually complies with the minimum requirements declared by EASA/FAA per ADS-B version.


texts: How to correct CG on a not leveled aircraft?

texts: I am tasked with weighing a fixed wing aircraft. the aircraft can not be leveled because the leveling points are damaged. therefor it is going to be weighed not leveled, an inclinometer will read a pitch angle and three scales will read the reaction from the LH and RH mains and nose. after the reactions are known and the pitch angle is know, how can I correct the cg for a leveled aircraft.


texts: Can an F-16 fly with conventional hydraulic powered controls without a computer controlled Fly By Wire System?

texts: Radio Controlled models of F-16s fly fine without computer controlled flight systems. Apparently these model aircraft are not unstable in pitch but probably positive in pitch stability. There may be trade offs in high AoA capability but it would seem that an F-16 with sufficiently forward CG would be able to fly using conventional or hydraulic controls like for example the F-4 or F-5.


texts: How did the controls work for variable-pitch props?

texts:
Variable-pitch propellers date way back to the 1930's and even earlier. I would like to know, what kind of controls they used? Some kind of lever or crank? How heavy were these controls? I'm thinking of the drag the propeller has, since even near landing, the prop could be spinning very fast and would be resistant to changing it's pitch.

I'm interested in the old days, before modern electrical control by wire.

Note: I am not asking how the variable-pitch mechanisms work. I might ask that in a separate question.


texts: Where can I find current downloadable tower, ground and approach frequencies for USA airports?

texts:
I have searched the FAA site and cannot find a spreadsheet with current freqs for airports, only incomplete lists.  Online flight planning tools must get query-able current freqs on a monthly basis, but I sure couldn't find them.

I'm looking for what Airnav, the Chart Supp US, AOPA flight planner all provide if you search on a specific airport, but in a format I can query from a personal spreadsheet.


texts: What is the relation between manifold pressure, RPM, and power, in a constant speed prop?

texts:
I know that there are similar topics here, one is mine even, but still I have few questions about constant speed propeller. My questions:

Why if we decrease RPM and maintain throttle lever setting the power output decrease?
Sounds like very basic knowledge but I heard a lot of versions and I want to reassure. Is tachometer on constant speed prop reading engine rpm or prop rpm?
If we move prop lever we are changing blade pitch and then rpm adjust to it or we are changing engine rpm and blade angle adjust to new rpm


texts: What is the difference between 'warning area' and 'ADIZ'? Are they overlapped with each other?

texts:
On FAR AIM, definition of warning area is

  Airspace of defined dimensions,
  extending from three nautical miles outward from the
  coast of the U.S, that contains activity that may be
  hazardous to nonparticipating aircraft

And on Wikipedia, definition of ADIZ is

  Airspace over land or water in which the identification, location, and control of civil aircraft is performed in the interest of national security.

I was confused because the definition of these two airspace is similar with each other. And I thought that those area could be overlapped with each other. Could anyone explain the difference, or at least an example chart that contains this two areas?

And if an aircraft tried to fly to the U.S territory from the sea, which area does the aircraft encounter first : 'warning area' or 'ADIZ'?


texts: What's the name and purpose of a barrier raised behind a carrier based jet?

texts:
I saw this picture in Wikipedia with a Su-33 jet on carrier deck with some barrier raised from the deck behind the jet tail:

What is this barrier for and what's the official term for it?


texts: What impact did the Concorde have on business of other sub-sonic airliners?

texts:
The Concorde was anyways a technical marvel of its time, and a status symbol for society. Its fares were well above the rest, costing USD2999 + taxes for a JFK-LHR journey. But, at the same time there are reports that British Airways indeed made $750 million from it, over 27 years:

  It was not that Concorde operations made losses. In fact, on an
  average Concorde made an operating profit of £30-50 million a year
  for BA. BA reportedly earned £1.75 Billion in revenue for Concorde
  services against an operating cost of around £1 billion during its 27
  years of commercial operation (1976-2003).

So, what impact did it have on the business of other sub-sonic airliners? Probably, economy class would not have been so much stricken, since its fares were more than 3 times higher. But what was the impact on business class travel of other airlines and airliners, between the destinations served by the Concorde?


texts: Are there 5000+ companies with IATA (two-character) codes?

texts:
From Wikipedia > List of Airlines

  There are around 5000 airlines with IATA codes.

From Wikipedia > List of Airlines Codes

  IATA airline designators [..] are two-character codes [..]

and

  after an airline is delisted, the code becomes available for reuse after six months

The last quotation suggests that no two airline companies can share the same IATA code.

Depending on the characters allowed, a two-character codes can make $26^2=676$ combinations or eventually $36^2=1296$ combinations. It would take at least 71 different characters authorized to register 5000 companies ($71^2=5041$). It is unlikely that 71 or more characters are authorized. It seems paradoxical to me.

What am I misunderstanding?


texts: Minimum turning radius (or maximum banking angle) of a commercial airplane

texts:
The context of the work: in an ATC model, we currently have a graph model to set the routes for different aircraft. We want to improve its precision by generating more nodes for each route and in order for these nodes to be feasible (i.e., reachable by the aircraft) you do that embedding the Dynamics of the vehicle in the generation of nodes.

Bottom line, I need some "citable" source where I can find the values for the minimum turning radius of an airplane. Since it is preferrable to be conservative than to implement something that cannot be done, I am looking for "large" commercial aircraft as I understand they will set an upper bound. That said, it is a research work so it doesn't need to be "the largest aircraft that ever cruised over the airspace", just some reasonably big airplane that is commonly used: Boeing 747, Airbus A380,etc..

Note: only Civilian flights are considered, therefore military crafts are not relevant here


texts: Can diplomats be allowed on the flight deck of a commercial European airline?

texts: If a diplomat were to request access to the flight deck with proper identification, would he/she be allowed to visit the cockpit of a commercial airliner during flight?


texts: Does lift generation create a vacuum over an airfoil?

texts:
According to Bernoulli’s principle, airflow speeds up over an airfoil which decreases the pressure, and I read somewhere that when airflow speeds up over an airfoil, this creates a vacuum. Is this statement true?

How would a vacuum above an airfoil be different from airflow separation?


texts: Is the NTSB hostile to pilots, as depicted in the movie 'Sully'?

texts:
This is based upon events portrayed in the movie Sully.  If the film is taken at face value, what we basically see is a (fairly brazen) stitch-up attempt by the NTSB (National Transportation Safety Board), where they try to steer an investigation towards a predetermined conclusion of 'pilot error' (and very nearly succeed) using:

Naively unrealistic computer simulations that assume a pilot would divert towards the nearest landing strip immediately after a birdstrike without needing any time to evaluate the damage to their aircraft, attempt to diagnose and troubleshoot the problem, or coordinate with air-traffic-control.
Similarly unrealistic simulations using real pilots who have been trained/conditioned to divert immediately after the simulated birdstrike.
The deliberate omission of the fact that the pilots only succeeded in their simulation attempts after multiple failed training attempts, up until the pilot involved in the actual incident calls BS on the whole charade.

The only motivation posited in the film for the NTSB's attitude was that the insurance company would have preferred a conclusion of 'pilot error'.  Thus, my questions are:

Is the film's portrayal of the NTSB accurate, either in terms of having a general anti-pilot bias or in terms of the particular investigation depicted having had an anti-pilot bias?
Why would the NTSB care about acting in the interest of insurance companies (particularly to the extent that they'd be willing to throw pilots under the bus to do so)?
Does an insurance company avoid a payout in the case where an aircraft is lost due to pilot error (as opposed to mechanical failure, birdstrike, or other unavoidable scenario)?


texts: How can I stop being too high or low when on base and final?

texts:
I'm a student pilot having trouble with landings, and problems are occurring in the pattern on base and on final;  I am either too high or too low. As a result, I feel I have lost confidence.

I feel like I am relying on my instructor to tell me what to do next instead of me flying the plane. How do I improve this situation?

Also, it has been suggested that I stop using the simulator as this is teaching me bad habits.


texts: What are the "channels" on the A320 Rudder Travel Limit Unit?

texts:
The KNKT's final report on last year's Air Indonesia QZ-8501 crash repeatedly mentions that the faulty solder joint on the Flight Augmentation Computer (FAC) caused an open circuit on "both channel A and B", leading to the repeated failure of the Rudder Travel Limiter Unit (RTLU). (Page 66 of the report has a photo of the offending solder joint and of the whole module.)
What are these "channels"? The only relevant mention I can find in the report is on p37, an extract from the Flight Crew Operation Manual, as follows (ellipsis mine):

In performing these functions the FAC uses independent channels:

Yaw damper
Rudder trim
Rudder travel limit
Flight envelope

...
If  a  failure  is  detected  on  any  channel  of  FAC1,  FAC2  takes
over the corresponding channel.

Are the "channels A and B" two of the output "channels" mentioned here? The last quoted line suggests that each channel is redundant between the two computers, in which case why would both RTLUs fail together?


texts: What prep work can I do before transitioning from SEL to SES?

texts:
I'm very interested in getting my SES rating.  Is there any personal studying or prep work that I can do to minimize time in the air and with an instructor?

EDIT: I do have my SEL pilot license already.


texts: Why are there so many aircraft designs which look generally profoundly similar?

texts:
The F-86, mig-15, Dassault Ouragan
The b-1 and tu-160
Concorde, tu-144, 2707

The low wing and T tail with two engines at the back. (CRJ, dc9)

The 'standard' shape with the mid aircraft wings, and vertical and horizontal stabilizers at the back, used from the E170 to the a380.

And while many general aviation craft are low winged or differ from a high wing tricycle single engine design, most seem to stick with that formula as well.

For some of the odder shapes, the question is 'industrial espionage?' but in the greater context, is it simple convergent evolution in that there are only so many shapes which are functional and useful so most things take on that general shape?


texts: Are there left seat qualifications specific to actual handling of the aircraft?

texts:
The following three posts explain that both yokes and side-sticks require changing the hand that holds the yoke/side-stick when switching seats:

Why are Airbus captain control sticks placed on the left when most people are right-handed?
Are there risks if the side joystick must be handled with a pilot's weaker hand?
Do some right-handed pilots fail to use the left stick of an Airbus?

I can imagine at least some difficulty for a newly promoted captain having to essentially re-learn everything (handling wise) from the left seat after logging thousands of hours from the right seat (regardless of the dominant hand).

So, what are the minimum qualifications for progression from right to left seat when it comes to handling the plane? Is there extra training involved? Does a left seat pilot hold extra qualifications for handling the plane?

Or is this a non-factor?


texts:
I am not a pilot - just a student & play Ace Combat  sometimes

So I turned off the flight turn assistant in the Ace Combat flight simulator/game & now I have to manually control bank & pitch to turn. I also like to use a little yaw for stabilizing myself.

If I am not wrong - both pitching & rolling are controlled by the control yoke in jets. So, when going for a right turn from level flight, what does the pilot do:

Push the yoke a little right (attain 90+ degree rightward roll) and then pull the yoke towards him (to pitch up - i.e. actually execute the right turning arc). OR
Pull the yoke in a diagonal way i.e. towards SouthEast (assuming pilot was initially heading north) or 4'o clock - and the flight's internal computers break down yoke movement movement into respective pitch and roll magnitudes.

Just curious.


texts: Would a flying-wing drone fly farther if filled with helium?

texts: I'm wanting to build a flying wing designed drone and I'm wondering if I were to fill the fuselage with helium if it would improve it's range.


texts: What is the process of obtaining a commercial license after revocation?

texts: I held a 2nd class medical and a commercial pilot license. My certificates were revoked due to an alleged DUI which I didn't get convicted of. I have been trying to contact every division in the FAA just to speak with someone about the process of getting my certificates back, however, due to COVID-19 not a soul is in the office nor, apparently, returning phone calls. Any ideas on which direction to go to obtain my certificates? Or possibly a direct number to someone to speak with about the matter?


texts: In a turbofan what holds the spinning axis?

texts: When the turbofan is spinning inside the housing, what holds the axis? All I know is that the axis holds the fan blades.


texts: How was the rotation direction decided for single engine propeller craft?

texts: Spitfire, FW-190, Ki-43... was it selected arbitrarily to spin counter-clockwise?


texts: Would random sitting arrangement be the best way of boarding for passengers?

texts:
This is more in relation to flights which have a single class of passengers with a short haul flight duration. Why don't airlines adopt random seating arrangement i.e. first come first serve basis. We already see business class passengers of having the flexibility of boarding at their own convenience.

This might solve the problem of boarding, and might also encourage people to board quickly.

To solve the issue of cabin baggage, we could have dedicated space for each passenger, by dividing the existing baggage space by the number of seats below. This would take care of 'greedy' passengers. Also, passengers can check beforehand if they are carrying excess luggage.


texts: Why does the Biot-Savart law give the induced velocity of a infinitesimal segment of a vortex filament at point P?

texts:
My question is about the proof of how the Biot-Savart law can be used for vortex filaments. This is what I have in my textbook:

However, I'm not certain how it was derived - I understand that the Biot-Savart law originally came from electromagnetic theory, but could anyone present the proof for it's use for vortex filaments?

Intuitively though, something seems off - a vortex filament is just made out of lots of individual vortexes put together in a filament, so shouldn't the induced velocity at a point P of an infinitesimal section of the filament be zero unless $d\vec{l}$ and $\vec{r}$ are perpendicular... but clearly it's not the case,
$$
 d\vec{V} = \frac{ d\vec{l} \times  \vec{r} }{ \lvert \vec{r} \lvert ^3}
$$
, which is nonzero even when $d\vec{l}$ and $\vec{r}$ aren't perpendicular


texts: How low can a helicopter fly above a residence if the helicopter is an air ambulance landing?

texts:
Two medical helicopters just located directly across the street from my home.  Their landing pad is less than 500 feet from my property.  When they land, the helicopter is only 100 to 200 feet above my roof and is causing stress cracks in my home. The noise and the fact that the downward wind from rotors is causing vibration in my walls. The pilots have many other options for directions to approach and land but use the shortest route.

What are my rights? Don't I have the right to quiet and peaceful use of my home?

After all, those helicopters are part of a business and I was here 10 years before they located in this unzoned area of Alabama.


texts:
How to read this step climb profile?

FL STEPS CYUL/0330/TUDEP/0340/NETKI/0350

I know CYUL is departing point but what do 0330 represents? The altitude in Feet?


texts: Why don't aircraft (commercial and military) use reflective visor windshields?

texts: Just like those used on an astronaut's helmet, these reflective visors can help in better visibility when facing the sun (or any bright light source). But the windshields of most aircraft (commercial and military) look transparent from both sides. The whole point behind the question is to find out if it was experimented and if yes, why was it dropped?


texts: Is there any mechanism in engine mount to prevent shock loads on engine while landing?

texts: How engine is mounted in wing is restricting motion in any direction but is it still resistant to shock loads, or is there any mechanism inside engine associated to bearings that will absorb shock loads that occur in spools?


texts: Understanding "non-WAAS G1000" in a 2006 Turbo 182

texts:
All,
I am trying to get my head around something my local avionics shop is telling me about a 2006 T182 that has a GTX345R fitted. Surely, the GTX345R adds WAAS capability but he referred to this configuration as a "non-WAAS G1000"

I feel like you'd need to be Stephen Hawking to understand this stuff!

Can anyone shed light on the way in which the addition of a GTX345R (replacing GTX-33) means it is not WAAS???

Thanks in advance,
Michael.


texts:
I was listening to RealATC for a United Flight UAL1074 which declared an emergency needing to return to Washington Reagan National Airport. During the ATC recording, the flight declares an emergency due to a passenger disruption.

ATC asks for something called the Passenger Disturbance Level. The Copilot replies with a Disturbance Level of 2. As I had never heard this asked for before, I was curious as to what the levels are for and what they each mean?


texts: Why does An-225 have anhedral wings though it is a cargo aircraft?

texts: What are the rationale behind this anhedral high mounted wing configuration? Is that usual for very large carge aircraft?


texts: Is a 20% forced transition in xfoil similar to adding a vg?

texts:
Is a 20% forced transition etc. in xfoil similar to adding a vg?

I understand a 20% forced transition in xfoil, is tripping the boundary layer from laminar to turbulent.  Isn't that what a VG does?

A classic shaped naca foil like 2415, has a max cl of 1.5.  I understand that vg's usually add a cl of about 0.5-0.7.

So... if I force a transition to turbulent at about 15-20% of chord in xfoil, shouldn't the max cl of a classic foil go up from 1.5 to about 2?

It doesn't....?!?


texts: Was the airframe involved in the LOT Flight 16 accident repaired?

texts:
The belly landing of LOT Flight 16 is known by many:

Wikimedia
YouTube

My impression is that a lot of aluminum was ground off by the runway. Maybe too much?

Question: What is the status of that aircraft today? Was it economically and safely repairable? Is it still flying?

And any general comments about the "repair or retire" decision after a costly breakdown or accident are welcome.

(I am impressed by the airmanship on that flight)


texts: How many controllers are there per frequency?

texts:
Imagine multiple controllers talking on the same frequency would be a nightmare for pilots and other controllers.

So in real life how many controllers are there for each frequency? If there are more than one, how do they split the work load?


texts: Do takeoffs and landings in a Pilatus PC-12 count for currency in a Piper Archer?

texts:
I just read this:

  No person my act as PIC of an aircraft carrying passengers unless, within the preceding 90 days, he/she has made three takeoffs and landings as the sole manipulator of the controls in an aircraft of the same category, class, and type (if required)

Does this mean that you are legal to take passengers in an Archer if you have logged three takeoffs and landings in the past 90 days in a Pilatus PC-12?


texts: Does this chart show a heliport in class D airspace without a control tower?

texts:
I was looking at the Los Angeles area on sky vector, and I noticed a tiny little triangular class D area right next to LAX. It shows that the height of the class D goes up to 2,500, but I couldn't see an airport in there, not even on the TAC.
Only if you click on "LA West Heli" on the top right on sky vector can you see that there is a heliport in that little area called "Chevron Refinery". On airnav, it says the identifier is 4CA6, and it says it does not have a control tower.
I have so many questions. Why is it class D if it has no control tower? Can a heliport even be class D? Why the actual heliport not appear on the sectional or even TAC? Can someone help me? :)


texts: What does "stuff it in the back right corner" mean?

texts:
I'm still catching up with Flightchops, and came across this episode about his first tail wheel solo.  As he touches down for his first landing (around 5:03 in the video) he says "Get ready to stuff it in the back right corner".  He says it again a few seconds later.

I am low time in tail draggers (about 3 hours post endorsement) and I don't remember ever hearing my instructor use this phraseology.

Question:

What does he mean by this?  Is this common aviation terminology or just something he picked up from his instructor?

I can make an educated guess that he means to deflect the stick to the rear and right to allow for a three point landing with a right x-wind, but I'd love to get confirmation of this from the experts.

Note: I did google this, and came up blank.


texts: What regulations apply to flying near blasting areas in Canada?

texts:
I was flying near CYPK the other day and for convenience and since I was close to it, reported as being "above the blasting area". My instructor pointed out better not to do that. That made me think about the legality of flying above a blasting area but I couldn't find anything about that, neither in the AIM, nor in the CAR.

On my VTA a blasting area is shown as a "striped circle", similar to a circular special use airspace. The CFS legend for that symbol says "CAUTION BLASTING AREA. Do not overfly at less than 3000' AGL". The CFS entry for Pitt Meadows CYPK says "Quarry blasting ops ... to 300 AGL".

Obviously it's a good idea to stay away from a blasting area and having read a bit about it since then, I won't fly over it below ~3500' in the future. For closure and future reference I would like to know:

What are the Canadian regulations around flying over/near blasting areas?


texts: Is there an API to retrieve airport departure and arrivals?

texts:
I am looking for an API to get the arrivals and departures timetable for any airport in real time, like this table on the EuroAirport website:

Are services like FlightAware or FlightStats relevant for me? I am a non-native English speaker so airport-specific language is a bit tough for me, I am not sure I fully understand what those APIs provide.

Edit : paying APIs are okay, I have a budget of around 100€ a month for this project


texts: What causes this error on the Collins 60A ADF system?

texts:
We've got a BAE Jetstream 32 equipped with a dual Collins 60A ADF system, and the co-pilot's side control head is:

displaying "FLAG 10" when we press the TEST button; We looked up the error code, but the only information we got is that the code corresponds to "ADF not locked in ADF mode" with no rectification. This is the first error of this type we've seen.
would not function for the last flight crew that flew it.

We tried replacing the controller, the signal adapter and the receiver. We've been banging our heads against this for hours. Anyone seen a similar failure, and know what we've been doing wrong?


texts: What certificates/medical are required to fly in Japan?

texts: I am FAA certified, but my medical certificate has lapsed. Would my pilot certificates and a fresh medical enable me to fly in Japan?


texts: What kind of flight counts toward the commercial 100 nautical mile cross-country flight requirement?

texts:
A question regarding the dual 100nm day/night 2 hours.

Does a 130nm flight with 1 stop halfway (over 2 hrs) count?
1 leg of 80nm, 2 leg 50nm.
Total time 2.5hrs.


texts:
Does anybody know what the icon inside the circle mean ?

Found at aviationweather.gov


texts: Why do airlines retire the flight number after a crash?

texts:
Perhaps it seems obvious, but I couldn't find a plausible reason why they do so other than that it evokes negative emotions among passengers and crew. Could there be other reasons to do so?

For example, flight number MH370 was retired as a "mark of respect" for the passengers and crew.

And out of interest, is there any case where an airline company reused a retired number for any reason or in certain circumstances?


texts: How much the Concorde secondary nozzle contribute to thrust?

texts: Does anybody knows how much did secondary nozzles bucket type on the Concorde's engines contributed to the increase of thrust during take of and sub-sonic flight? This is picture of the nozzles  and here is air flow during take of  all images from this link https://www.heritageconcorde.com/variable-exhaust-nozzles  source states that secondary nozzles reduces noise, as well as improved engine performance. I suppose performance means thrust?


texts: Is it possible to fly a tandem-rotor helicopter after a single rotor failure?

texts:
Tandem-rotor helicopters, such as the Boeing CH-46 Sea Knight and CH-47 Chinook, are helicopters with rotors distant by more than 10 m.

Photo by Cpl. Ryan Carpenter on SNAFU

It seems unlikely a single rotor could sustain the force moment created by the failure of the other rotor. On the other hand it seems to me it would be difficult to have one rotor in autorotation and one powered.

If this is possible, how would the pilot fly the helicopter? If it's not possible, why?


texts: What can cause a sudden jump in Indicated Air Speed?

texts:
My aircraft heading is 321 with constant Static pressure, wind speed and steadily increasing Ground Speed.
Meanwhile, there was a sudden jump of 10kts in IAS from 140 to 150 kts withing a span of 1 sec.
For this span, Wind direction is rapidly changed from 176 tp 300 degree A.

Is wind direction is cause for IAS jump ?


texts: Why can't turbojets or turbofans be overtemped or overtorqued the way turboprops can?

texts: Turboprops that aren't FADEC controlled can be overtorqued or overtemped if the power lever is moved too far forward yet I have never heard of a jet that can't be "firewalled", FADEC or not. Why is this?


texts:
Recently the FAA released some new regulations that require drone operators, including hobbyist, to register drones with the FAA.

As I am a novice in both aviation and legalese, can someone please break down the regulations and give me a guideline in layman's terms for whether or not I need to register a drone?


texts: Why is the maximum endurance for a piston aircraft at sea level?

texts:
The Canadian Flight Training Manual stated this when talking about maximum endurance:

For reciprocating engines, maximum endurance is achieved at sea level.

The book does not explain further as to why. Air density is my first guess, when the engine gets a better mixture of air to burn with its fuel, and so we get the most power for the same amount of fuel.
But if that is true then it sort of contradicts why maximum range is at higher altitude.


texts: How does density altitude affect performance, temperature, and pressure; and how is it calculated?

texts:
I'm trying to better understand density altitude. If the density altitude at Rand Airport (for example) is 8300 ft:

What does the 8300 ft mean? Does it mean that at that altitude, aircraft performance will be at its lowest?
What does the 8300 ft mean in terms of air quality? Does it mean that at that altitude, the pressure will be at its lowest and the temperature at its highest?
And why 8300 ft specifically? Was it calculated? If so, how?


texts: Why would landing the space shuttle on water have been unsurvivable?

texts: For an aircraft unable to reach a runway on land, ditching in water is a common and, generally, highly-survivable option; however, for the space shuttle, according to Wikipedia, "...an ocean ditching was not survivable" (although it lists no source for this claim).  What was it about the space shuttle that made it incapable of ditching into water in a survivable manner?


texts: How are evolution and variants of aircraft considered by certification authorities?

texts:
Recently, both Boeing and Airbus launched "new" aircraft as a modernized version of their respective best sellers (B737MAX and A320neo). To narrow the question down, I will consider the A320 and the FAA, but the same goes for the B737 and almost certainly many more aircraft families, and I hope for other certification authorities as well. I'm not really clear on the difference between type, model and series but I think the difference may be relevant for the certification process. Perhaps highlighting this difference is enough to answer the question.

Wikipedia lists multiple variants of the A318. Do the A318-111 and the A318-121 require different certifications?

Moreover, when adding a variant to the family (here adding the A318 to the family composed of the A319, the A320, and the A321), do the certification authorities consider this aircraft as a totally new one or only as a variant of existing one (many shared components)? Can this consideration lighten the certification process?

Is the new version (A320neo) considered as a new aircraft by the certification authority and does it thus require the same set of tests as a new aircraft?

In short, when a new aircraft is an evolution or a variant of a previous one, how is it considered by certification authorities?


texts: How would one perform a more thorough preflight of the engine on a single-engine airplane without easy access to engine compartment?

texts:
On a lot of the Cessna 172 and 182 airplanes I have seen, there isn't an easy way to look at the engine in the engine compartment and see all of the components during a preflight. In fact, usually the only thing you can really do to see the inside of the engine compartment is to peer through the tiny oil/fuel sump door.

The POH for a 1978 Cessna 172N in the Preflight Checklist simply says:

Engine Oil Level -- CHECK

Before first flight of the day and after each refueling, pull out strainer drain knob...

Propeller and Spinner -- CHECK for nicks and security.

...

Carburetor Air Filter -- CHECK for restrictions by dust or other foreign matter.

...

So I know that while it's not a requirement to see the components of the engine and look at the engine compartment, it seems prudent to add something to your preflight that might help give you an indication if you should investigate further before attempting the flight.
How do you more thoroughly preflight the engine of your aircraft when you can't access the engine compartment without completely removing the cowling?


texts: Which UK airport uses different approaches for noise reduction?

texts: I remember hearing about a British airport that had two approaches that were used on alternating weeks. They implemented this pilot project (no pun intended) so that different houses would be overflown each week, giving residents the impression that noise from the airport was reduced. What airport was this?


texts: Is there a list of part 121 and/or 135 operators?

texts:
While looking into this question, I found a list of certificated air carriers on the US Department of Transportation website (there's a list of commuter air carriers too). But, the list doesn't say if each one operates under part 121 or part 135, which the DoT seems to consider an FAA question anyway:

  As noted above, the economic authority issued to air carriers by the
  Department is separate from the safety authority (commonly referred to
  as Part 135 or Part 121 Operations Specifications) granted to them by
  the Federal Aviation Administration (FAA).  For safety authority
  application procedures and related questions, air carriers should
  contact the appropriate FAA flight standard district office based upon
  the geographical location of the air carrier

The FAA site has a lot of information about part 121 operations, but at least as far as I could see there's no list of 121 or 135 carriers anywhere on their site.

Is there a list somewhere of current part 121 and/or 135 operators?


texts: Navier-Stoke vs Prandtl lift calculation

texts:
Why Prandtl had need to calculte lift with his lifting line theory (1933) if Navier-Stoke published equation long time ago 1822?
Also Navier-Stokes option is far more "accurate" then lifting line,N-S  are basics of CFD...


texts: Where exactly is the 700 and 1200 foot AGL for class E airspace measured from?

texts: Are the AGL numbers measured from the Maximum Elevation Figure listed on the sectional?


texts: Why is FAC 1 cycled OFF to ON during a dual engine failure?

texts: I was reading in the Airbus A320 FCTM regarding the dual engine failure procedure. The ECAM tells us to recycle FAC 1 OFF THEN ON. Why do we have to recycle FAC 1 specifically? I opened the QRH and it shows this also.


texts: What ground-based, airline job in the 1940s could have involved radio communications?

texts:
My mom worked for United Airlines in the mid 1940s in some communications capacity: she communicated by radio with United aircraft only, and she wasn't an air traffic controller.  She went to school in Kansas City in 1942 for communications.

Could anyone help me figure out what her job would have been?


texts: Does a headwind/tailwind affect your rate of climb?

texts:
I am still confused whether a head wind or tailwind would affect the rate of climb. Since in a HW/TW condition our a/c is basically still climbing in the same parcel of air, it is just that parcel of air is moving with or against our course hence increasing/decreasing the horizontal distance covered to get to the target height. This means that the time needed to get to the target altitude is not affected at all, but the horizontal distance is.

Yet my friends have been insisting that with a headwind an aircraft would climb faster to the target height, as the headwind helps create more lift by increasing the amount of air passing through the wings.


texts: How did this F/A-18's execute a "low-boom maneuver"?

texts:
The Engadget article NASA will publicly test quiet supersonic technology in November says:

  The administration plans to conduct a series of public tests around the coastal city of Galveston in November. The F/A-18 Hornet aircraft at the heart of the tests will perform dive maneuvers that produce louder sonic booms out at sea, while quieter sonic "thumps" will take place over Galveston proper. After that, "at least" 500 local volunteers will provide feedback on what they heard, while audio sensors will provide more definitive noise readings.

and links to the NASA YouTube video NASA Social: Low-Boom Maneuver:

  This footage is from a NASA Social event at Armstrong Flight Research Center during which the F/A-18 was flown to produce a regular sonic boom and then a low “boom” by performing the dive maneuver described in this story. The normal sonic double boom occurs at 0:43. The low “boom” occurs at 02:34. The rest of the footage includes a flyby, planes on the ground with NASA Social participants, a visit to the Ikhana UAS and a pilot signing.

Question: What would be a simple way to understand what a "low-boom maneuver" is, and how would an F/A-18 execute it? In this case would it require any modification of the Hornet's configuration?

Is producing the boom during a dive of particular relevance to the reduction in sound level, or is this just a convenient way to do this particular experiment? Since the sound level as well as the reduction of the level for the low-boom maneuver at ground level may have a directional dependence, I'm wondering if the direction of the dive needed to be carefully planned to be representative of how the reduction would work for civilian air travel boom reduction, where dives are (thankfully) less frequent.


texts:
Looking for Polars for Liebeck LI74 with a Cl of 4.8!!

Does anyone have any info on this foil?


texts:
A statement in this question, asking how to pay fees for using the airport services, without being at the airport, inspires me to ask a question.

Quote:

  (Yeah I know... you gotta pay for an ILS approach... yuk.)

How much does it cost to do an ILS Approach (for the pilot when he pays the bill)?
How much does it cost to do an ILS Approach for the airport (Electricity, Staff, Maintenance, Chart-making, ...)?
Is this listed as seperate item on a bill or is it included in the airport fee?
If it's included, how much would it be?
What percentage is to cover maintenance cost and what is the payment for the controllers?
Are there differences between aircraft size?
Are there differences between ILS Category?

I am asking this question for any country in Europe, because, as Dan Pichelmann pointed out, in US ILS Approaches are still free.

Would appreciate answers.


texts: At what operating temperatures would the Trent 900 need to operate, to equate to the efficiency of current geared turbofans?

texts: What is the minimum optimum operating temperature (in degrees Celsius) that would be required for the Trent 900 to operate at, for it to attain the level of fuel efficiency of current geared turbo fans?


texts: How is a sideslip maintained (aerodynamically)?

texts:
(Public domain image that I've modified.)

The initial rudder deflection to the left creates a side force that points right and yaws the plane to the left.

NASA puts it this way:

  For the vertical stabilizer and rudder, the orientation of the airfoil causes a side force to be generated. With greater deflection of the rudder to the left, the side force increases to the right.

But in a forced slip, isn't the fin's airfoil now in a negative angle-of-attack (from the perspective of the earlier force). How is the force maintained?

I'm looking for an answer regarding only the yaw, ignoring the roll/pitch side effects.


texts: For training with a grace month, is it legal to fly in the month after training expires before going to school?

texts:
Most 135 training/testing says something like this:

  §135.343   Crewmember initial and recurrent training requirements. No
  certificate holder may use a person, nor may any person serve, as a
  crewmember in operations under this part unless that crewmember has
  completed the appropriate initial or recurrent training phase of the
  training program appropriate to the type of operation in which the
  crewmember is to serve since the beginning of the 12th calendar month
  before that service. This section does not apply to a certificate
  holder that uses only one pilot in the certificate holder's
  operations.

Before that though, 14 CFR 135.323 states:

  §135.323 - Training program: General.

  ...

  (b) Whenever a crewmember who is required to take recurrent training
  under this subpart completes the training in the calendar month
  before, or the calendar month after, the month in which that training
  is required, the crewmember is considered to have completed it in the
  calendar month in which it was required.

  ...

So let's say that I completed initial training in March.  This says that if I complete recurrent training in February or April that they consider the training to have been completed in March.

So what happens if a year passes and recurrent training is due.  I don't make it in February or March, but the company schedules me for recurrent training towards the end of April.  Is it legal for me to fly in April before I go to recurrent training?

At this point, I don't meet 135.343 (because I am no longer within the required 12 calendar months) but I haven't been to training yet, so 135.323 doesn't really apply.

From my interpretation of the regulations I would say no, however every 135 company that I have ever flown for continues using pilots until they go to school, or stop flying at the end of the late grace month if they still haven't gone.  The POI's have never complained about it.  I feel like I must be missing something.

Is it legal for me to fly 135 trips during the late-grace month??  Note that the same the same scenario applies to 61.58 PIC checks as well, which also have a provision to train during the eligibility period (the month before or the month after it is due).


texts: Does GA flying in your own plane count toward a Airline Transport Pilot license?

texts:
The video Why the World is Running Out of Pilots discusses a pilot shortage, and notes the tortuous path to an airline transport pilot license (specifically). It claims there are 1500 flight hours needed.

I also know general aviation is in steep decline over the last 50 years, whilst the cost of GA aircraft have gone up dramatically.  I wonder if there is a connection between these two things.

If you own a small plane and fly yourself around in the "Mighty Luscombe" for fun or Youtubing, do those flight hours count toward the aforementioned 1500 hours?

Is there a floor to the minimum quality of airplane which "counts" - do you need a Cessna class, or will a light sport aircraft, experimental, parasail, or a towed glider suffice?

Does these 1500 hours differ in any way from the ~230 hours needed for a "commericial license", or can you do it all in the same Cessna?

In a general sense, would it help the pilot shortage if the government would act to promote general aviation as a hobby, growing it back to where it was?


texts: Do the FAA's InFO publications carry any regulatory or legal weight?

texts:
The FAA publishes Information for Operators documents giving:

  valuable information for operators that should help them meet certain
  administrative, regulatory, or operational requirements with
  relatively low urgency or impact on safety.

Some of these documents seem to offer interpretations on regulatory matters, and are sometimes cited as such. In some cases, these interpretations may provide permission to operate more freely. However, I could imagine that in the case of others, the interpretations may prove to be more restrictive and burdensome than a plain reading of the regulations.

What regulatory or legal weight do do these InFO publications carry, if any?
Since these notices are directed at certified operators, does the answer vary depending on the audience?


texts: Are there any airliner crashes that can be definitively attributed to Mach tuck?

texts:
Mach tuck (the tendency of aircraft to develop an increasingly nose-down pitching moment at speeds above its critical mach number) caused a number of crashes of high-speed fighter aircraft before the phenomenon was well-understood, but I haven't been able to find any information regarding whether early jetliners (or modern ones, for that matter) were involved in any crashes that could be definitively attributed to mach tuck.

Were there any?


texts: Why is the VOR reference and variable signal modulated at 30 Hz?

texts:
VOR signals radiated from the ground beacon are modulated at 30 Hertz.
What is the reason behind this?


texts: How much thrust could a 400 mm EDF produce?

texts:
There's a 195mm EDF from Schübeler that produces 25 kg of thrust at a peak power consumption of 15 kW: https://www.schuebeler-jets.de/de/produkte/hst

Now, my question is: How much thrust could you approximately get if the diameter was 400 mm instead of 200 and how much more power would you need ?

Thanks for your answers !


texts: Why are there so many different propeller shapes?

texts:
While doing an image search, I found these images of propellers:

and

Some appear to be straight-ish on the leading edge and curved on the trailing, some curved on the leading edge and straght-ish on the trailing, and symmetrically curved and some pretty squared off.

It seems like, well, a propeller is a propeller. They all need to push the air back in a way as to propel (hence the name?) the plane forward.

Wouldn't there be a mathmatically 'best' design?


texts: What is the meaning of the term "fly back only" in AMM documents?

texts:
I am reading an AMM document and I don't get the ideas below:

  Examine cracks in area A1 and A3:

  (a) Accept with an inspection each 100 hours, cracks on the inner or
  outer shroud if there is:

  A single hair line crack at the leading edge of the blade, possibly only on the coating on all blades (Area A1).

  (b) Accept for fly back only, cracks on the outer shrouds if they
  are:

  A maximum of 0.08 in. (2.03 mm) long on up to 10 blades (Area A1).

I don't get the whole idea of the sentence (a): why is that: the cracks are on the shrouds then they turn to be on the leading edge of the blade ?
And what is the meaning of the term "fly back only" in the sentence (b) ?


texts: Effect on pressure and/or volume of a real vs. ideal compressor

texts: I'm looking at the Brayton cycle and trying to understand what happens when we move from the ideal cycle (isentropic compression/expansion) to the real world where we have adiabatic compression/expansion with associated compressor and turbine (in)efficiencies. I understand with adiabatic processes when compressor/turbine efficiencies are less than 1, that there is now an increase in entropy and an increase in temperature vs. the ideal cycle. My question is, with a higher temperature at the end of compression (and expansion), is there any associated change in the pressure and/or volume? Said another way, I'm struggling to square off the occurrence of a higher temperature at the end of compression, but is the pressure and/or volume higher as well?


texts: In a 777, what would happen if the auto-pilot and the altitude hold failed at the same time?

texts:
I know nothing about a Boeing 777 flight controls.

In general,
I know that the speed of an aircraft is controlled by the throttle on the center console. I have never heard of an automatic speed control. I believe the pilot manually adjusts the speed.
I have heard of altitude hold control. You set it and the system keeps the aircraft at the same altitude. Is this independent of the auto-pilot?
And of course there's the auto-pilot. It makes the aircraft go in a direction you want it to go.

If the pilot does not intervene, what would happen if the auto-pilot and the altitude hold failed at the same time?

Does the aircraft climb or dive?  Dose it oscillate up and down?
Does the aircraft roll over?
Does the aircraft turn?
What about speed?
If it continues in some fashion, what is the effect of the fuel consumption in the different tanks? Is it automatically controlled? What happens if that control fails?


texts: When cruising, is any moment that a pilot will reduce his/her airplane speed?

texts: Say, a pilot is piloting his/her jet commercial airplane and suddenly see cumolonimbus or a dark cloud. Then, should the pilot reduce his/her airplane's speed to avoid turbulence?


texts: If pitching moment creates drag, how can high and low moment airfoils have almost identical drag polars?

texts:
If pitching moment creates drag, how can high and low moment airfoils have similar drag polars?

Let's call a symmetrical airfoil like NACA0015 a low moment airfoil having no moment at an AOA of 0.

Let's call NACA 2415 a medium moment airfoil. Let's say it has a medium moment at an AOA of 0.

Let's call Eppler399 a high moment airfoil, and it has a high moment at an AOA of 0.

yet....

I understand pitching moment creates drag. While the above airfoils have vastly different moment polars at an AOA from -10 to + 10, they almost identical drag polars,at an AOA from -10 to +10.

How can this be?

See pics below


texts: Which aircraft endure the highest Max Q's (aerodynamic pressure)?

texts:
What are the highest aerodynamic pressures encountered in any aircraft? And does this limit the maximum speed of any aircraft at certain altitudes? Broadly, 'how fast can you go [at a given altitude]?'

Where dynamic pressure $q$ is: $$q = \frac{1}{2} \rho v^2$$

$\rho$ is local air density, and $v$ is true airspeed.

I'm mostly concerned with high performance fighters/bombers. Here's some data I've culled (Mk-12A and 787 added for reference):

#   | Airframe      | Mach       | Speed     | Altitude    | q (kgf/m^2)
----|---------------|------------|-----------|-------------|------------
1.  | Mk-12A        | Mach  6.15 | 2,100 m/s |       0 ft  | 273,000
2.  | Mk-12A        | Mach 22.6  | 6,900 m/s | 100,000 ft  |  39,300
3.  | X-51A         | Mach  5.1  | 1,500 m/s |  64,000 ft  |  11,100
4.  | HTV-2         | Mach 20.   | 5,812 m/s | 125,000 ft? |  10,700
5.  | F-111         | Mach  1.2  |   410 m/s |       0 ft  |  10,400
6.  | B-1A          | Mach  1.2  |   410 m/s |       0 ft  |  10,400
7.  | B-1B          | Mach  0.9  |   310 m/s |       0 ft  |   6,100
8.  | X-43A         | Mach  9.6  | 3,000 m/s | 109,000 ft  |   4,800
9.  | Skylon        | Mach  5.5  | 1,630 m/s |  85,300 ft  |   4,600
10. | SR-72         | Mach  6    | 1,800 m/s |  90,000 ft? |   4,400
11. | Space Shuttle | Mach  1.3? |   400 m/s |  35,000 ft  |   3,200?
12. | XB-70         | Mach  3.0  |   880 m/s |  73,000 ft  |   2,500
13. | SR-71         | Mach  3.2  |   930 m/s |  78,740 ft  |   2,300
14. | Concorde      | Mach  2.0  |   600 m/s |  60,000 ft  |   2,100
15. | Boeing 787    | Mach   .85 |   250 m/s |  35,000 ft  |   1,200

Airframes #3, #4, and #5/6 are quite different from each other, so I'm surprised they share roughly the same max $Q$. Is 11,000 kgf/m^2 a common limit?

Note: All figures are for level flight except for the Mk-12A (reentry), Space Shuttle (ascent), and HTV-2 (glide).

[Mk-12A]: Current reentry vehicle for the Minuteman III ICBM, houses the W78 warhead (350 kT). Figures are for reentry.
[HTV-2]: Rocket glider.
[B-1B]: "[top speed] is limited by the need to avoid damage to its structure and air intakes," according to Wikipedia. The B-1B used less structural Titanium and a simpler fixed geometry inlet when the speed requirement was lowered from the B-1A.
[Skylon]: Obviously doesn't exist yet. Reaction Engines' "user manual" for the Skylon discusses the flight profile.
[SR-72]: Obviously doesn't exist yet. Lockheed Martin discussed Mach 6 cruise. 90,000 ft cruising altitude is just my placeholder value.
[Space Shuttle]: Figures for ascent.

Some background and purpose: For fun, I'm trying to design a hypersonic long-range heavy bomber. I was curious what would limit the maximum low/mid-altitude speed: drag (available engine thrust), max $Q$ (structural strength), or skin temperature (thermal protection system)... but I'll get to that in another question.

I've read through nearly all the aerodynamic, military, aircraft design, aircraft performance, and jet engine tags, looking for answers. (Really, this is a marvelous community.) Finally realized I could ask my own question.

I've tried to follow the etiquette as best as I can, but I'm pretty new to Stack Exchange, so let me know if I should change anything :) Thanks!


texts: Which are the requirements to fly a N-registered aircraft operated by a non-US airline?

texts:
There are several non-US airlines which operate N-registered aircraft for domestic and international flights.

Let's say for instance Avianca, which has N-registered aircraft but is a non-US airline (flag carrier of Colombia with headquarters in Bogotá and main hub at El Dorado International Airport). What are the pilot certificates required to fly those aircraft? FAA or Colombian pilot certificates?


texts: I know that the empennage is the tail section of the aircraft and includes the horizontal and vertical stabilisers. But what is the empennage height? Is it the height of the horizontal stabiliser from the ground or is it the height of the vertical stabiliser?


texts: How are the costs managed in a codeshare?

texts:
How do the airlines manage the costs invovled in a codeshare?

As all airlines are selling tickets, (might be at different prices) but only one of them is operating the flight.  So, how do the airlines decide who will pay how much for the crew, fuel and catering and who will earn what?

And how do you justify:

  When an airline sacrifices its capacity to other airlines as a code share partner, its operational cost will generally be reduced to nil. (Source:Wikipedia)


texts: Why did Boeing not create a new 737 instead of just upgrading the old model?

texts:
This documentary claims that

James McNerney - Boeing's first CEO without a background in aviation, made the decision to upgrade the 737 series to 737 MAX instead of developing a new model.

Is this true? If so, why did Boeing make the decision not to make a new model instead of upgrading a 50 year old one?


texts:
What is the relation between sweep angle and lift-to-drag ratio?
Ans does depend on wing planform?
For subsonic speeds.


texts: Would a slotted flap still work if the prop is located mid wing between the wing and flap?

texts:
Would a slotted flap still work if the prop is located in a slot mid wing between the wing and flap?

This would be for a distributed propulsion application for an multi prop ultralight triplane, where the each prop would need to provide distributed propulsion for multiple wings vertically.


texts: Why do some airports have class E airspace to the surface only at certain times?

texts:
Below is the depiction of the Truth or Consequences airport on the VFR sectional.  Notice that it states that Class E to the surface is only effective for certain hours.

The Chart Supplement lists the effective hours as 9:00 - 17:00 local (converted from Zulu).  My question is why are the Class E surface hours limited to 9:00 to 17:00 local and not effective for 24 hours each day?  I understand that airspace reverts to less restrictive airspace when a control tower closes but there is no airport tower at this airport or a towered airport anywhere near this airport.


texts: What is this fighter jet seen at Centennial Airport?

texts: This is my first post here! yay! Today I ate at the awesome "Perfect Landing" restaurant at Centennial Airport. My dad said he thought they were FA-18s but I honestly have no idea. It was awesome because we saw the pilots through the window of the flight crew lounge in their military suits. We also saw them go out with some little kids and their families to show them the jets while they were being inspected before takeoff. Really cool to see.


texts: Don’t seats that recline flat defeat the purpose of having seatbelts?

texts:
Virtually all first-class airline seats, and many to most business-class seats, recline all the way down, either as lie-flat seats (where the seat reclines to a 180º seatback-seatpan angle, but the fully-reclined seat is still tilted somewhat forwards relative to the cabin floor) or flat-bed seats (where the seat reclines to a truly flat surface that can also, as the name indicates, serve as a bed).

These seats are, of course, equipped with seatbelts, but I’m having great trouble seeing how even a tightly-fastened seatbelt would provide any protection to a flat-lying occupant, as any significant longitudinal force would cause the occupant of the seat to slide under the belt and out of the seat.1 2

Although these seats, like all airline passenger seats, are required to be locked in the fully-upright position except in cruise flight, this still leaves the occupants (especially those in flat-bed seats) vulnerable during the (sometimes quite long) portion of the flight when they are allowed to recline their seats to flatness; a moderate head-on (or tail-on, for that matter) gust would be enough to separate these occupants from their fully-reclined seats, as would any other event capable of suddenly increasing or decreasing an aircraft’s inertial speed too quickly for the “fasten seat belts” sign to provide any warning (not, as noted above, that fastening their seatbelts would actually provide any significant degree of protection to the occupants in question, but it could conceivably induce them to derecline their seats in preparation), such as a flight-control malfunction or evasive action to avoid a MAC (both of which produce large speed excursions secondary to rapid changes in attitude and altitude).

For that matter, even vertical accelerations with no longitudinal component would still be expected to injure flat-lying passengers more severely than those in an ordinary sitting position, for reasons illustrated below:

Am I missing something?

1: This is known as submarining, and is a major problem with car seatbelts (even with seats that don’t recline at all), which are much harder to fasten tightly around the pelvis than aircraft seatbelts.

2: If the belt were fastened tightly enough to pin the occupant to the seat even under considerable longitudinal force, this would

be highly uncomfortable for the occupant, and
upon the application of significant longitudinal forces, drag across the occupant’s abdomen until catching on their ribcage, causing severe internal abdominal injuries plus likely breaking the bottom few ribs.


texts: What is the effect of wingspan on wing stiffness?

texts:
In an article in aviationweek about flight testing the GE9X, this statement is made.

  To reduce aeroelastic interaction between the testbed and the big
  engine, GE has also stiffened the wing by removing the 6-ft. tip
  extension developed for the standard -400 series. The reduced span of
  just over 195 ft. will reduce potential exposure to limit cycle
  oscillation and maintain an unrestricted test envelope.

How does removing the wingtip extension make the wing stiffer?

What is "limit cycle oscillation"?


texts: How does the range of a single- and twin-engine for small aircraft compare?

texts:
I know that one difference between these two types of small aircraft are that in a twin engine, one engine can continue working if the other suddenly fails.

Wouldn’t a single engine plane weigh less and thus can fly longer on a specific amount of fuel comparative to a twin engine plane?


texts: Why is a strake placed on the fuselage in front of the tailplane on the Hawk aircraft?


texts: Why do small aircraft rentals charge per flight hour?

texts:
Why do airplane rental companies charge per flight hour (using hobbs time), instead of either MX hours (tach time) or based on the amount of fuel used?

Wouldn't a 3-hour long cross-country flight be much cheaper than three hours spent in pattern work?

In my opinion, rental rates would seem more logical if they are based on MX time.


texts: Could some one explain me with the mathematical relations on how the double bubble fuselage cross section (example A380) is designed.


texts: What are the FAA regulations concerning controlled descent of a light payload?

texts: I'm part of a High Altitude Ballooning club. Our main goal for this year is to achieve controlled descent of our payload. We plan to use Magnus force cylinders to go about this. I have found nothing in FAA documentation that specifically mentions something of this sort requiring extra clearance, but am still somewhat worried about putting the payload 100,000 feet up and then dropping it down in a controlled manner without being absolutely certain, as an object falling out of the sky in a directed manner could obviously garner concern if people didn't realize what it was. Does anyone know if there are specific regulations for this sort of thing, and whether there are or not, what should I look into doing? Thanks for the help


texts: Do I need complex endorsement in each class or type of aircraft?

texts:
I have experiences with PA28R and got a complex endorsement from my instructor.
Now, I am working on multi add-on and flying DA42 Twinstar.

Do I need another complex endorsement that specifies the class and the type of the  aircraft for DA42 checkride?


texts: Too soon to pass the IATRA exam? (Canada)

texts:
I just finished the IFR group 1 rating this week. Currently at 220h Total flight time with CPL, no job in sight (of course), and wondering if I should start studying for the IATRA now or wait until I'm closer to 250h and/or a job?
Thanks in advance, have a delicious day!


texts: Why Helicopter compulsory need helipad to land?

texts: Our Country ministers helicopter didn't land because there is no helipad exist in my location, helicopter needs small place to land, then why Helicopter compulsory need helipad to land?


texts: Could an aircraft like a Boeing 777 take off with flaps fully deployed?

texts: I have wondered this for years.  Could an aircraft successfully take off with the flaps fully extended to the landing position? To make this more concrete, let's say a B773-ER at ATL runway 8R.


texts: What limits the lifespan of helicopters?

texts: The lifespan of aircraft is generally limited by metal fatigue. This is true for fixed wing aircraft; is it also true for helicopters? What is the determining factor for helicopter useful life?


texts: Does the landing distance required for a wet runway needs to be within a certain range of the landing distance available?

texts:
Conform the regulations the landing distance required (LDR) for propeller engine aircraft needs to be within 70% of the landing distance available (LDA). The LDR for a wet runway needs to be multiplied by 1,15 (115% LDR). I was wondering whether this 'wet LDR' also needs to be within the 70% of the LDA to meet the regulations, or does it only need to be within the total LDA?
And does the same count for contaminated runways?


texts: What causes a military aircraft to be decomissioned?

texts:
The Harrier jump jet, while still in use in other countries, has been decomissioned in the UK, as the article below from the DailyMail mentions.

The Harrier jump jet for sale on eBay at £69,999

What are the causes of a still capable aircraft to be decomissioned?

Is it due mainly to political reasons, like this other article suggests in the case of the Harriers?

US military to buy Britain's scrapped fleet of Harrier jets

  The US military has agreed to buy Britain’s entire fleet of Harrier
  jump jets after they were controversially scrapped under the
  Government’s austerity measures.

In action: Harrier T2 XW269 on active service in Gutersloh, Germany


texts: What problems do you start run into when an aircraft is disproportionally long?

texts: For example, lets say we design a plane with the same lengh as the A340-600, but has the width of an embraer erj-140. Assuming everything works, what problems would we run into in regards to aerodynamics?


texts: How common is an airliner activating reverse while still in flight?

texts: Around 1977, I watched a DC-9 landing at Guacimeta airport, Lanzarote, Canary Islands, Spain, opening the flaps reversing thrust of both engines just over the airstrip end, but some 9 feet over the ground. Of course, it fell down that height as fast as a stone. Is this usual?


texts: What is the difference between a US Part 121 Supplemental Air Carrier, and a US Part 135 Air Carrier?

texts: I am a little confused after knowing the concept of Part 121 Supplemental Air Carriers in the US. What is the difference with Part 135 Air Carriers? My understanding is that both operate in a non-scheduled basis.


texts: What does BUS mean in the startup procedure?

texts: I noticed the term BUS in the startup procedure of a 737. What do BUS on, off and transfer mean and what is their significance?


texts: What's the acceleration and absolute minimal RWY length for an A320 during take-off?

texts:
TL;DR: An A320 takeing-off with full thrust is able to reach $V_{TO}$ (77 m/s) in only 26 seconds and in as few as ~ 1.000 metres. Is that really true?

Last time I traveled with an A320 I was again impressed by the acceleration during takeoff. I think it's not outstanding (compared to others) but nonetheless impressive. A cause might be that passengers are somehow exposed to the powers and cannot influence it. But I enjoyed it and it made me doing some calculations.

I gathered the following data:

usual take-off speed $V_{TO}=150$ knots (source)
required runway length $2000 \text m$ (source)
max. thrust per engine $\approx 120 \text{kN}$ (source)
MTOW $78 \text{tons}$ (source)

For constant acceleration along a path the following rules apply:

$$\left.
\begin{array}{}
s = \frac{1}{2} at^2 & \Leftrightarrow & t = \sqrt{ \frac{2s}{a} } \\
v = a \cdot t        & \Leftrightarrow & t = \frac{v}{a}
\end{array}
\right\}
\Rightarrow
a = \frac{1}{2}\frac{v^2}{s}$$

With the data from above this gives an acceleration from 0 to 100 km/h (or 62 mph or 28 m/s) in approximately 18.5 seconds and about 52 seconds for reaching the take-off speed. That sounded a bit lame compared to my 100hp station wagon.

So I investigated further, this time from Newton's point of view, $F=ma$, which gives an acceleration of $a = \frac{2 \cdot 120.000 N}{78.000 kg} \approx 3 \frac{m}{s^2}$. That gives 0…100 km/h in about 9 seconds. This far better coincides with my gut feeling as a pax.

But my second approach, $a \approx 3 \frac{m}{s^2}$, also resulted in the following conclusion and question:

An A320 takeing-off with full thrust is able to reach $V_{TO}$ (77 m/s) in only 26 seconds and in as few as ~ 1.000 metres. Is that really true? I was amazed at this because they all say the required RWY length is twice as long.


texts: How long does it take on average for a control surface to deflect by one degree?

texts:
I know this should vary quite a bit (because of aircraft size / use / build / actuation / control surface weight), but I was wondering if anyone here could ball-park some numbers on how long it would take a control surface (aileron/flap/vertical stabiliser) to deflect by one degree on average.

I am writing a small aircraft simulator, and would like to try and use realistic numbers if possible.

If these figures are too variable, I would love to know some ball-park figures for some example aircraft if possible.


texts:
Note that this is more of a Physics question than an Aviation one.
  This topic has been extensively covered on the Physics Stack Exchange site, and the answers there are recommended reading for anyone curious about the forces and physics involved.

If you had a giant treadmill that was an infinite plane, had an infinitely adjustable speed, and could tread along any of its dimensions, could an airplane take off from it?


texts:
I have heared at ATC communication that some aircraft uses a heavy word in the call sign.

What does heavy means?

When it is used?

Is it used when aircraft is heavier than 200-300 tons?


texts: Ever since I was 10, I've always wanted to pilot an airplane by myself. I don't want to do it for the money I really just want live that "dream of flight" but where I grew up in a society that doesn't favor "dreams" or even flight. I really want to know, isn't there a place I could go and just fly without having to pay anything. To be honest, the fees at flight schools are really outrageous and discouraging. I want to know if there is a place in this world that I can just live that dream. By the way, sitting in passenger plane crowded with a bunch of people for several hours doesn't count at all. Please I hope that someone can help me.


texts: What is an NTAP when referenced in a NOTAM?

texts:
When reviewing notices to airmen (NOTAMs) for the KDNL airport today (08 April, 2016) there's a particular NOTAM that references an NTAP with a number. What's an NTAP? How does one go about looking one up?

!DNL 03/008 KDNL SVC SPECIAL EVENT MASTER'S GOLF TOURNAMENT SEE NTAP 1604031100-1604112359


texts: What material is used on the wing surface of this airplane?

texts:
This is one of the Redbull's 2015 Flugtag contestants; I was wondering what material is used on the wing surface of this airplane?

video here.


texts: Can a controller clear you through an SFRA?

texts:
A pilot I know (lets call him Joe) recently had a minor run in with the FAA after he skirted the edge of the Washington DC Special Flight Rules Area (SFRA) while returning to Leesburg (JYO).  Here are the details:

Joe was returning from KOMH.
Joe was trying to get on the ground quickly to avoid a wall of convective sigmet from the west, moving east quickly and threatening to engulf Leesburg and his landing in a small GA plane.
Joe was in contact with the Leesburg Tower Note: Leesburg is NOT usually a towered airport.  However Leesburg has been a test site for mobile air traffic control tower and that tower was operational when this occurred.
Joe was instructed by the tower to "Proceed directly to Leesburg".  He immediately turned directly towards Leesburg (right turn shown on chart), received permission to land and landed.
Joe was provided with a number to call by the tower.
Joe was interviewed by someone in the FAA, told he had skirted the SFRA, received a warning and the case was closed with no further action.

Though the case was closed it was still the FAA's position that a violation of the SFRA rules had occurred.

What I find confusing about this case is that, if ATC instructed Joe to "proceed directly to Leesburg", doesn't that mean they cleared him through the portion of the SFRA he will need to fly through to comply with their instruction?

Research done for this question

I have taken the SFRA training required to fly VFR in the SFRA and have again reviewed this material after hearing of Joe's incident.  I've found nothing in that material that conclusively answers this question.
I have reviewed this question/answers about flying in the Washington DC SFRA.
I have reviewed this general question about flying in SFRAs.
I have reviewed the NOTAM associated with Ingress/Egress to/from Leesburg airport.
I have reviewed already asked questions and did not find this specific question having already been asked.


texts: Transition level has to be readback and what about transition altitude? is it also required to be readback by the pilot?

texts:
These are the readback requirements, source by https://www.skybrary.aero/index.php/Read-back_or_Hear-back
a) ATC route clearances;
b) clearances and instructions to enter, land on, take off from, hold short of, cross or backtrack on any runway; and
c) runway-in-use, altimeter settings, SSR codes, level instructions, heading and speed instructions and, whether issued by the controller or contained in Automatic Terminal Information Service (ATIS) broadcasts, transition levels.


texts: What is the maximum age limit for getting a pilot licence?

texts: Can I do pilot training courses even after age 26 ?


texts: Can quadrotors be used for commercial passenger flights?

texts:
Recently, I have been conducting research on more efficient means for vertical lift transportation. One direction I was thrown in was the use of a quadrotor system  with vector thrust and artificial stability. All of this is done using a system of ducted fans and electric motors. I would love your answer on "Does a system like this sound like a safe and quiet means to transport passengers?"

The name of the program is UV-4, and although it is being tested on flight simulation as an unmanned cargo delivery craft, I wonder if it also makes sense as a passenger aircraft.

Would this type of aircraft produce less noise than a traditional transport category helicopter of the same size? Length = 41ft (Prop blades are ducted and aircraft has two electric motors)
Can a ducted fan rotorcraft create regenerative energy using magnets or other method to create square waves?
This experimental is a UAV; could you picture a piloted passenger aircraft?


texts: Why do you need to subtract when using a climb/descent performance chart for an altitude other than sea level?

texts: If you look at this chart you see we subtract 3 minus 1, 9 minus 2, and 30 minus 4 in the example calculation. My question is, why do we subtract these numbers? Do we subtract the same numbers each time? Nowhere on the performance chart does it give any explanation!


texts: If we use upper surface blowing and externally blown flap on the same wing will lift correspondingly be very high?

texts:
With two engines, one above and one below the wing, will the lift be the sum of two lift increments (produced by upper surface blowing and external blowing)? I am trying to make a jet suit and I am interested in incorporating this phenomenon in it.

When a jet of air blows over or under an airfoil with a deflected flap, it gives an immense amount of lift due to the change in direction of the jet via the Coanda effect. The engine can be placed either above and below and can achieve lift coefficients up to 7 (when any one of the methods - upper surface blowing or externally blown flap - is used)
What if we use two of them at the same time? To which value can the lift coefficient increase?


texts: What are good apps to help with VFR navigation on my first solo?

texts: Currently I am a student pilot in Spain (Barcelona) and I am 2 days away from my solo. I wanted to ask if there is any good application that will help me on VFR navigation since I'm allowed to go to all Barcelona in my solo, but I am afraid if I get lost I see my self weak in VFR flights and specially to locate my position so any good app in the iPhone device that will help me in navigation because I want to visit the whole Barcelona and not just staying at places that I know because I will get bored for sure.


texts: If there was an engine malfunction, could we breathe contaminated air?

texts: If the engine on airliners has for example, an oil leak, can the oil or other substances contaminate the air on the passenger cabin? How would this situation be avoided?


texts: What are the relative braking contributions from wheel brakes, spoilers and thrust reversers?

texts:
What is the relative contribution to braking forces in a typical large commercial aircraft  from the three different devices contributing to braking after touchdown:

Wheel brakes
Speed brakes / Spoilers
Reverse Thrusters

The relative contribution should change with velocity so even nicer if we have the velocity depended thrust contributions. e.g. Reverse Thrusters provide more braking at the initial high velocity part of the roll out.

I'm posting a illustrative (but totally made-up) graph to clarify for what I was looking for:

I am looking for either empirical data or theoretical predictions for the thrust. Qualitatively I'd expect the spoiler contribution to fall off with a square law dependence on velocity. I'd think the reverse thrust offers a somewhat constant component but perhaps higher initially due to parasitic drag by the clamshells? Not sure, and this is what I'm trying to get: A quantitative relationship.

In case the answer will vary hugely depending on aircraft, I'm open to any specific case being illustrated.

Let's use the limiting case of full brakes with anti skid on.

PS. Since spoilers directly add to drag as well as indirectly help braking by dumping lift teasing out their braking thrust contribution might be harder?


texts: What vertical flight profile could be expected from an aircraft if the pilots were incapacitated?

texts:
If there were nobody at the controls what kind of vertical profile could be expected from, for example, a modern airliner?

After reaching the cruise altitude I assume the pilot just sets a nav route and altitude on the onboard computer or at least set the trim to avoid having to constantly adjusting the altitude manually.


texts: How can I determine specific heats of gases for turbojet engine calculations?

texts:
I'm in a combustion lab and we are performing experiments on a turbojet engine. However, I am having some trouble calculating the exit velocity and compressor/turbine powers of the engine.

Consider the nozzle exit, where the exhaust gases go. Assuming 100% adiabatic efficiency of the nozzle and applying the 1st law of thermodynamics gives
$$
\frac{u_e^2}{2} = h_{0e}-h_e = c_{p,N}(T_{0e}-T_e)=c_{p,N}T_{0e}[1-(p_a/p_{0e})^{(\gamma_n - 1)/\gamma_n}],
$$
assuming $p_e = p_a$, the ambient pressure. In the lab, we've set up thermocouples that measure the stagnation temperature and pressure at the exit, as well as ambient conditions. My problem, however, is that I have no idea where to get $c_{p,N}$, the specific heat of the gases in the nozzle from. I've looked up in a reference book that the average specific heat ratio $\gamma_n = 1.36$, but this still doesn't give me the specific heat that I need because I don't know the specific gas constant $R$ for these gases. For reference, it is an SR-30 turbojet with Jet-A fuel.

In addition, I have the same problem when calculating the power outputs. Assuming that all of the power of the turbine is transmitted to the compressor,
$$
\dot{W_T} = (\dot{m_a} + \dot{m_f})c_{p,T}(T_{04}-T_{05})=\dot{m_a}c_{p,C}(T_{03}-T_{02}) = \dot{W_C}
$$
Again, I have no clue what the specific heats are, only their ratio. Is there some way I can calculate these quantities or look them up somewhere? Or even find the specific gas constants somewhere?


texts: Why is there so much movement of the sidestick during this takeoff?

texts:
Watching a video entitled Airbus A330 Takeoff Sidestick View, there appears to be a lot of side-to-side movement of the sidestick, as well as a lot of pushing the nose down:

I was under the impression that movements on the control column should be smooth and not erratic — what is the reason for the side-to-side movement? As far as I can see on the MFDs, there is no heading change prior to 02:50 (which appears to be done by the A/P anyway). Is it turbulence?

Also, what is the reason for pushing the nose down? Is the plane naturally trying to pull up at too high of an angle?

This landing video appears to show even more erratic control. Is this normal?


texts: Is there a "Quid Pro Quo" of flight following?

texts:
I like to use flight following whenever possible because who wouldn't want traffic pointed out to them for free?

But just as the controllers are doing me a favor, they sometimes ask me to do them a favor.

For example, depending on a given runway configuration, they might vector me way far out from the airspace. During times like these I end up just wanting to terminate. I'm far clear of the class C, and they've added 20 minutes to my flight.

How is it that they move me so far away when plenty of aircraft who didn't even bother to call up approach are flying so freely without incident? To anticipate objection, this is while staying out of the charlie itself.

Is there anything I can do to ask if I can change altitude to avoid rerouting? I'd hate to call up, have them assign me a squawk, and then say "like to terminate" moments later.


texts: What are the advantages of 3 spool over 2 spool turbofan engines?


texts: Which engine manual must a pilot legally use?

texts:
Many aircraft have engine/prop performance information provided by the manufacture such as Bonanza, Cessna, Mooney, etc AND the engine manufacture. The performance or recommended settings may vary between the two-- i.e. Bonanza E-series Continental engines with Hartzell props.

Additionally there may be pilot organizations or other reputable sources that diverge from these manuals. Such as operating the engine LOP (lean of peak).

As a pilot, does one manual have legal precedence or may I choose any source of data for operating the engine and prop?


texts: Do any private charter schools sponsor your pilot school tuition?

texts: Do any US or European private charters pay for your jet pilot school in exchange for contract pilot service?