texts:
I need some help identifying a LEGO plane.

The LEGO set 7292, Propeller Adventures, features a twin engine airplane, with conventional landing gear, and a bubble canopy.  There are no pontoons on the wings

Assuming it's based on a real plane, does anyone have any ideas?


texts: How did the Wright brothers measure the maximum airspeed of their 1904 plane?

texts:
The Wright brothers used during their 1904 trials (105 in total, according with their claims) a Richard anemometer mounted on Flyer II (there are numerous pictures on the net with such a device). The instrument just integrates the airspeed and when you stop it you read the displayed distance and divide it by the flight time and so get the average airspeed of the airplane during the entire flight.
The question is: How did the Wright brothers measure that maximum airspeed of 70 ft/s that occured during a flight characterized by a 59 ft/s average airspeed (see the letter to Octave Chanute below)?
Wilbur Wright, “Letter to Octave Chanute (the mentor of the Wright brothers)”, Dayton, August 28, 1904.

“Since the first of August we have made twenty five starts with the #2
Flyer. The longest flights were 1432 ft., 1304 ft, 1296, ft. and 1260
ft. These are about as long as we can readily make on our present
grounds without circling. We find that the greatest speed over the
ground is attained in the flights against the stronger breezes. We
find that our speed at starting is about 29 or 30 ft per second, the
last 60 ft of track being covered in from 2 to 2¼ seconds. The
acceleration toward the end being very little. When the wind averages
much below 10 ft per second it is very difficult to maintain flight,
because the variations of the wind are such as to reduce the relative
speed so low at times that the resistance becomes greater than the
thrust of the screws. Under such circumstances the best of management
will not insure a long flight, and at the best the speed accelerates
very slowly. In one flight of 39¼ seconds the average speed over the
ground was only 33 ft per second, a velocity only about 3 ft per
second greater than that at starting. The wind averaged 12 ft per
second. In a flight against a wind averaging 17 ft per second, the
average speed over the ground was 42 ft per second, an average
relative velocity of 59 ft per second, and an indicated maximum
velocity of 70 ft per second. We think the machine when in full flight
will maintain an average relative speed of at least 45 miles an hour.
This is rather more than we care for at present.  Our starting
apparatus is approaching completion and then we will be ready to start
in calms and practice circling.”

Richard anemometer


texts: Can I simply use multiple turbojet engines to fly supersonic?

texts:
the jet engine FJ33 produced by Williams International produces around 6 kN thrust (maximum, at sea level).
Imagine: to fly supersonic, I need for my aircraft 9 kN of continious thrust.
I am wondering now: is it possible to use just two FJ33 jet engines, so that I would just double the maximum thrust ?
What are the restrictions to this?
My thoughts:
If I fly supersonic with a jet engine which is designed actually for subsonic flight, there can be many aerodynamic effects like stall and strong rise in drag at the gondola, for which the engine is not designed: So I would need a diffusor to bring the supersonic flow down to an optimal flow velocity for the FJ33.
Is this correct? Do you know some other restrictions?


texts: Where can I find registration information of a private aircraft registered in Germany?

texts:
Is there any way (website, database etc.) where I can get the registration information of a privately-owned general aviation aircraft registered in Germany?

(Germany has pretty extensive privacy laws, but it would seem that aircraft registrations should be a little bit transparent and verifiable...)


texts: Why do some flights make turns shortly after takeoff?

texts:
I have seen that flights will make a turn, after traveling some large distance (say after some kilometers), but that can be done before.

Why not flying directly like in 2?

I am not expecting a passenger flight to do like fighter jets and perform nearly vertical take-offs, or some other manoeuvrers.

Are these flights restricted to do so, or is there any reason to behave so? Or did I misunderstand something?


texts: Why is the lower deck of the Airbus A380 curved like a single deck airplane?

texts:
I recently traveled on the lower deck of an A380 and the section where the side walls of the fuselage and its roof top meet is curved just like any single deck airplane.

Credits: Wikimedia Commons

If there is a deck above me (which there definitely is) then why does the lower deck have to be curved near the top? Shouldn't it be straight on the sides?

Shouldn't it be straight when there is one more deck above it?
I'm sure that it's just the interior that is curved and the external structure is indeed straight but does it serve any important purpose?

Details:

Airline:  Emirates
Aircraft: A380-800
Seat: Row 58

Here is what i saw:

Notice that even the roof is curved, is there a structural reason for that as well? On the side wall one of the rows has an extra covering on it, I'm almost sure that is to cover one of the brackets as mentioned in the answer below but even without that the whole cabin is curved.


texts: Can I bring a person with me while getting landing current if they're a licensed, current pilot?

texts:
It's been over 90 days since I've been flying, but I have a biennial flight review coming up pretty soon and would like to prep for it.

The regulations regarding this seem to be extremely vague, but is it legal for me to fly around, do my landings, log PIC time, and such with another licensed, current pilot in the plane with me?


texts: Where can I find sample data required for Engine Condition Monitoring?

texts:
I'm trying to find some sample data required for Engine Condition
Trend Monitoring to analyse and predict when an engine might fail.

I went through a lot of research papers and (kind of) understood the parameters needed for Engine Condition Trend Monitoring. From what I've understood, I need Exhaust Gas Temperature, Fuel Flow, Low Pressure Fan Speed, High Pressure Rotor Speed, Engine Pressure Ratio and EGT Margin data.

I'm doing this as a part of my college project and I need some sample data to start working.
Also, please correct me if I'm wrong because I'm very new to all this.


texts: Is there an equivalent of cash transportation in air cargo?

texts:
Some cargo (cash for banks, precious art pieces, gold, jewellery,...) are transported in bullet proof trucks with armed guards while travelling by road. Sometimes it may also be escorted by police.

Is there an equivalent for air transport? How is protecting handle for such cargo when transported by air (both at the airport (load breaking and ground operations) and in flight)?


texts:
I heard that sometime an aircraft fly inside a cloud, and I'm wondering how that works - how clearly can the pilot see while inside the cloud?
What if a cloud is "too large"? (Is there a maximum size of cloud a pilot can fly through?)


texts: Can water-cooled brakes be used for takeoff aborts?

texts:
Airliner engines are sized to continue the takeoff if one engine fails after it has become too late to brake. This means that the oversized engine has to be lugged around the whole flight, increasing weight and drag. Creating traditional brakes that could withstand the heating of a rejected takeoff just before rotation would also add significant weight.

The brakes on the SKYLON spaceplane boil water during abort, and it appears that the steam is dumped. The water is fed by pyrotechnic blowdown. Following a successful takeoff, the water is dumped overboard. This saves weight for the remainder of the flight.

My question is, can this approach be used to save weight on airliners?

SKYLON info.
https://web.archive.org/web/20151129034506/http://www.reactionengines.co.uk/tech_docs/SKYLON_Users_Manual_Rev_2.1.pdf
https://web.archive.org/web/20110615104534/http://www.reactionengines.co.uk/tech_docs/JBIS_v57_22-32.pdf
https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36826.0;attach=1073534


texts: Is there a landing gear system that extends automatically to prevent belly landing?

texts:
To my knowledge, most aircraft with retractable gear are equipped with a landing gear warning system that makes repetitive beeping sounds in case the pilots try to land without the gear down.

I imagine big jetliners like Airbus and Boeing would have a far more advanced landing gear warning system, but does any of them have a landing gear system that extends automatically if the pilots fail to extend the gear and continue their descent for landing despite the warning?


texts: Autorotation: Positive Pitch during descent phase possible?

texts:
I was wondering if a rotorcraft, that descends very slowly compared to its nominal rotor rotation rate (for example an RC Helicopter vertically autorotating with 3m/s descent rate and 2200RPM on the rotor) can maintain the rotor rotation rate even though it is having a positive collective pitch.
Is this possible? If so can it be sustained or is it just for short time frames?
The following image might enhance the understanding (Source)
look at the speeds and look at the lift/drag curve, if the lift/drag ratio is big enough this should work, right?


texts: How does one reset an attitude indicator that doesn't have a cage?

texts:
I was up flying today – VFR – and the attitude indicator tumbled. It's a 6-year-old RC Allen 22-7, without the ability to cage, so I just wound up letting it be all off-kilter until things stabilized... which took almost an hour. The vacuum was in the green the entire flight, and at no point was I doing any wild maneuvering.

Is there anything I could have done to accelerate the process? Could I have caused damage by not landing and shutting down?


texts: What are the US Customs requirements upon returning to the US after pre-clearing customs in the US Virgin Islands?

texts: I have heard conflicting information regarding pre-clearing customs in the USVI.  On one hand, I have heard that once you clear customs you are done and don't need to do anything special on arrival.  But the I've also heard that you need to land at an Airport of Entry upon arrival and notify local customs of your arrival.  I have even called Customs and Border Protection and gotten conflicting answers!  What is actually required?


texts: why are tips of airplane wings "bent' up?

texts: Why are the tips of wings on new aircraft folded up? Is it safety or efficiency that is the concern? I have done multiple searches and all I ever seem to get are wingtip shoes!


texts: What resources can direct me to real estate with landing strips?

texts: I am looking for a website or places to look at estate / personal residences in PA, DE, MD, VA that have landing strips already in place.


texts: Is the route which takes the least time always the one with least fuel-burn?

texts:
Geographically longer paths may require less fuel than the shortest (great circle) path. But what about time ?

Is the most fuel efficient route always the one that has the aircraft in the air for the shortest amount of time (assuming equal speed setting, e.g. LRC) , or not ?

Users here seem split on this question:

  « The most fuel efficient route is the one that has the aircraft in
  the air for the shortest amount of time. » (source)

and:

  « It's possible that the route that results in the smallest fuel burn
  is not the necessarily the route that takes the least time. That's true
  more often than not, but if to get the most favorable winds you had to
  stay low, you might burn more fuel. » (source)

So which one is it ?
And, if possible, please provide a clear explanation why.


texts:
Can you identify this plane?

Unknown airplane

I have just found the photo on a CD together with many other planes and helicopters. I have no clue regarding the place where the picture was taken, the time and the type of the plane.


texts: Why can't pilots manually fly a low visibility approach instead of using auto land?

texts: Pilots have instruments that help them land. But in low visibility they are required to use auto land. Why can't they rely on their instruments at those times?


texts: How much freight can a Boeing 737-800 NG carry if the majority of seats are removed?

texts:
In the context of the COVID-19 crisis, I read reports of underused Boeing 737-800 NG aircraft being converted (by technicians in airports, not by factories) to cargo planes for medical equipment. How much freight (in tons) can such an airplane transport? How much weight can the place below each seat withstand? The flight distance would be about 5000 km. It appears that one such airliner carried only 9 tons also, as can be seen in the images, it was loaded close to its maximum capacity. I guess the freight (200000 masks FFP2) was light.

Boeing 737-800 NG

VIDEO with such a Boeing 737-800 NG full of medical equipment

Press release:

  9 (nine) tons of medical equipment brought from China by a Tarom aircraft - Bucharest, April 3, 2020. In the middle of the crisis generated by the coronavirus pandemic, a Boeing 737-800 NG aircraft has been reconfigured to import from China 9 tons of medical materials. The plane took off from Bucharest Otopeni airport on April 2 and through Almaty (Kazakhstan) reached Shenzhen (China) and then returned on the evening of April 3. Two Boeing 737-800 NG passenger planes have been reconfigured.


texts: Why Not Just Replace All the Fan Blades?

texts: It looks like operators will have to remove all their P&W powered B777s from service until they have checked the engines.  Since the problem seems to be fatigue (which is a function of time) in a front fan blade, why not just replace all the blades in the front fan while you have it in maintenance?  What would be the cost of that compared to an inspection?


texts: Let's take the case of a stock Cessna 150, chained to the ground, standard day conditions. The engine is running at full power (say 2500RPM) and the propeller is absorbing its full output. Is there a formula that allows the calculation of the volumetric rate of flow of air through the propeller disc for this static test case?


texts: Is it better to increase speed in a climb?

texts:
In straight and level flight, lift is determined by speed and angle of attack.  If we are heavier, we must go faster to generate more lift, at the same angle of attack.  At the same speed, angle of attack must be increased for more lift, hence the saying "stall speed increases with weight".

We know lift is less than weight in a descent, because the drag vector has a vertical component opposite weight.

We know lift = weight in level flight.

We know the wing is much more efficient than the prop at producing lift.  By simply raising the nose in a condition of 2400 lbs weight and 600 lbs thrust, sin angle × 600 obviously does not equal 2400 - cos angle × 2400.

We know in a climb there is a vertical component opposite lift.

Does this not in effect make the plane "heavier"?

Does this not allow us to keep optimal AOA, and steady state (not curving up or down) flight, at a slightly higher airspeed when climbing?

Should we not pitch to a slightly higher airspeed in a climb for maximum aerodynamic efficiency?


texts: What was the reason why 9M-MRO burned more fuel on one engine?

texts:
MH370 Factual Information reported "Right engine consumes average 1.5T more fuel per/hour compared to left engine" on p.28 (page 47 on page count)

http://mh370.mot.gov.my/download/FactualInformation.pdf

Looking at spotters photos on the web I spotted the following difference:

Some kind of visible replacement (partial or total) to the left engine was made after Oct 28 '13 and before Jan 22 '14.

Before - Two shades, longer curving, bigger bulge on top engine border before exhaust.

After - One shade, steeper curving, smaller bulge on top engine border before exhaust.

Google Drive document with links to 9M-MRO photos (I can't post more than 2 links since not enough reputation still)

https://docs.google.com/document/d/1tkY6H8zQmOyJj0M2_gd_j81iDr2MeumBoIlrYNtbcus/edit?usp=sharing


texts: How can you calculate the gliding distance for a remote controlled jet?

texts:
Is there a way to calculate the gliding distance for a remote controlled (RD) jet aircraft, in case of engine failure? We have some telemetry data on the model, giving us speed and altitude so as to plug them on an equation or other model in estimating the glide distance, but we would not want to actually risk destroying the jet by testing a real life scenario.

So, for example, our maximum allowed altitude is 500ft Above Ground Level and its speed is about 150 knots; we are interested in calculating the gliding distance if engine power is lost or cut off (the engine is automatically cut off if the jet flies outside radio control range).


texts: How can a pilot become established on the KBIV, ILS or LOC Rwy 26 Approach?

texts:
Consider KBIV (Holland) in west Michigan:

Now consider the ILS / LOC to Rwy 26 at KBIV:

Questions:

There is a note on the IAP: "Procedure NA for arrival on PMM VOR/DME airway radials 004 CW 091" Does this mean only V55, V193, V274 or V170 or does it mean any radial between 004 to 091 off of PMM?
There is no feeder route on the plate with NoPT. Does this mean the course reversal at JAVPO is mandatory?

From experience, most of the time, it is vectors to final without a course reversal. My question is more about the charting, not the real world result, and what to do if the radar was broken that day...
How do I get to KBIV?


texts: How possible is a successful landing just with 1 wing?

texts:
Having in mind this famous F-15 incident :

Would this be possible with any other fighter-jet? Or was there something really specific to F-15's design that allowed this ?
Would this be possible at all with any commercial aircraft ? Specifically for those that have their engine(s) mounted on the rear ? or what about for those that have engines mounted on the wings, but only with a partial wing loss (eg having both engines intact) ?


texts: What are the requirements to get a private pilot's license in Indonesia?

texts:
I am interested to get license to pilot small civil aircraft (up to max. 4 passengers including the pilot him/herself). I read here that there is no age limitation to get the license as long pass the medical check.

What is the required knowledge to get the license? Is anyone here has the shareable pilot training and testing material?

Edit:
I am and Indonesian and stay in Indonesia. The license I want to get is for private slow aircraft such as Cessna which the speed should not more than 300km/h. Passengers are family members or friends, not commercial.


texts: Can boundary layer blowing increase transonic efficiency?

texts:
One of the problems faced by transonic aircraft is flow separation by recompression shock. Can the pressure drag that arises due to this flow separation be reduced by re-emerging the boundary layer past the shock?
In order to draw a valid conclusion about efficiency, let's compare the TSFC of a turbofan with the drag cancelling fuel consumption of energising the boundary layer.


texts: How can the runway allocation process be optimised?

texts:
I would like to write a programme that would be able to find the optimal arrival sequence for a given list of aircraft on a given airport.
By optimal I mean in terms of delay, fuel burn and runway throughput

Before this, I'm trying to collect information on the matter because I'm totally novice. I have a few questions

Do air traffic controlers only use the First Come First Served (FCFS) principle to assign runways to aircraft or are there other algorithms ?

I've read that this principle can prove inefficient because, for example, it doesn't consider aircraft "size". I've read that a sequence of 5 small aircraft followed by 5 large is better than one alternating 10 large and small aircraft because less spacing required. Is it true ?

Do you have other examples showing that the FCFS is not optimal ?

When is a runway allocated to an aircraft ? When it reaches the Initial Approach Fix ?

Thanks a lot for your help!

Sorry for the mistakes, english is not my native tongue


texts: From which rating would it be easier to transition to an Osprey? Fixed-wing or rotary-wing?

texts:
If the future of flight was to be on aircraft that were a hybrid of fixed-wing and rotary-wing (for example the Osprey), assuming they had similar technical abilities and the same number of flight hours, who would have an easier time flying an Osprey?

Or to put it another way, is the Osprey closer to a plane or to a helicopter?


texts: Can an airline lay off its flight attendants and use pilots to fill the role?

texts:
IcelandAir recently announced that it will be laying off its entire flight attendant staff, and plans to have pilots fill the role in the meantime.
Can an airline lay off its flight attendants and replace with pilots without requiring further training or certification? Generally, pilots are trained to fly the airplane and oversee the safety of the flight - but are they qualified to act as flight attendants? Is there any area a flight attendant maybe more qualified than a pilot, excluding passenger service and a smile on the face?


texts: How to reverse course when there is no published course reversal?

texts:
Coming from the SW on the RNAV RWY 15 KONO, how do I align myself with the final approach course?  There is only one IAF and no published course reversal.  Is it up to me how I get established inbound?
[RNAV 15]


texts: What model is this strange airplane-helicopter combination?

texts: I'm a local historian in Fort Collins, CO and I'm trying to find out anything I can about the helicopter/plane image in the attached picture. The only thing I know is that it was parked in a early Fort Collins airport.


texts: Why does the DC-8-70 have the same MTOW as the DC-8-60, despite its more powerful engines?

texts:
The DC-8-70 is a more-or-less straight reengine of the DC-8-601, replacing the obsolete JT3D-3B low-bypass turbofans of the DC-8-60 with the CFM56-2C1 high-bypass turbofan.  According to Wikipedia, the maximum takeoff weight of the DC-8-70 was unchanged from that of the DC-8-60 (which resulted in the DC-8-70, with the heavier CFM56, having a slightly lower payload capacity than the DC-8-60):

  The DC-8-71, DC-8-72 and DC-8-73 were straightforward conversions of the -61, -62 and -63 primarily involving replacement of the JT3D engines with more fuel-efficient 22,000 lb (98.5 kN) CFM56-2 high-bypass turbofans with new nacelles and pylons built by Grumman Aerospace and fairing of the air intakes below the nose. The DC-8-71 achieved the same end but required more modification because the -61 did not have the improved wings and relocated engines of the -62 and -63. Maximum takeoff weights remained the same, but there was a slight reduction in payload because of the heavier engines. All three models were certified in 1982 and a total of 110 60-Series DC-8s were converted by the time the program ended in 1988. DC-8-70 conversions were overseen by Cammacorp with CFMI, McDonnell Douglas, and Grumman Aerospace as partners. Cammacorp was disbanded after the last aircraft was converted.[10]

Emphasis mine.

But maximum takeoff weight is determined by engine power,2 and the CFM56-2C1 has nearly a quarter again as much thrust (98 kN; 22 klbf) as the JT3D-3B (80 kN; 18 klbf), which should result in a proportionate increase in MTOW for the CFM56-2C1-equipped DC-8-70.

So why does the DC-8-70 have exactly the same MTOW as the DC-8-60, despite its significantly-increased engine power?

1: The DC-8-72 and -73 are literally just reengined DC-8-62s and -63s; the DC-8-61 required some additional modifications to make it into the DC-8-71.

2: It's the maximum weight at which the aircraft is physically capable of attaining liftoff speed on an infinitely-long frictionless runway at zero density altitude with one [for twinjets] or two engines [for more-than-twinjets] inoperative; beyond this weight, the aircraft has insufficient one-or-two-engines-out thrust to push it fast enough to generate enough lift to lift off.


texts: Circa 1942 Republic of Ecuador - Can someone identify the aircraft in the background?


texts: Would ground effect and FOD ingestion be factors at high speeds close to the ground?

texts: How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground? Also wouldn't the engines ingest FOD at that power setting that close to the ground on the approach?


texts: Why is Germany not able to read data from the Boeing 737 MAX black boxes?

texts:
It is my understanding that Germany stated it does not have the capacity to read the new software, declining Ethiopia's request:

  "The French announcement resolved uncertainty over the fate of the two
  recorders after Germany’s BFU said it had declined a request to handle
  them because it could not process the new type of recorder used on the
  737 MAX jets, in service since 2017."

Does anyone know which requirements were missing?


texts: How do aircraft keep fuel from freezing while in flight?

texts:
On aircraft which fly above 30,000 feet, the temperature can often can get to temperatures below Jet-A's freezing point.

For example: at 36,000 feet the standard outside air temperature is -56.5°C (-69.7°F) and is well below Jet-A's freezing point of -40°C/F.

What measures are put in place on aircraft to mitigate the risk of the fuel in the tanks freezing and preventing the engines from operating?


texts: Why do large turbofans generally have many more LP turbine stages than HP turbine stages?

texts:
In almost every large turbofan I see, the LP turbine stages outnumber the HP turbine stages by a factor of at least 2. Here's a photo of the RR Trent 900:

The Trent 900 (like most Rolls-Royce turbofans) is a 3-spool turbofan, rather than a 2-spool. But even here, my observation holds. There are far more LP turbine stages than the middle or high pressure stages.

Why is this?


texts: Did Solar Impulse flight in commercial airspace and have kind of type 23 certification?

texts:
I read that the amazing Solar Impulse back in 2015 had circulated around the globe for 500 hours. It flew with speed 70 km/h and altitude of cruising 28000 ft. My questions are below

Did it fly in the commercial airspace? if yes then did it have kind of type 23 certification for small aircraft?
I have searched about the system of it such as flight control system and autoflight, but found nothing. What kind of the system was used in solar impulse? Did it have typical system with small aircraft such as Dassault Falcon or Pilatus?
Maybe anyone has detailed information related to solar impulse system such as flight control, autoflight, etc?

Thank you


texts: Is there anything a copilot can do to stop a pilot from doing anything while flying?

texts:
Is there anything a copilot in a commercial aircraft can do to stop a pilot from doing anything while flying?

As I see it, there are two scenarios:

The pilot is going to do something malicious, in which case the copilot could physically try to restrain or disable the pilot.
It's not malicious, but just something that is a bad idea (say could get the pilot fired or in legal trouble). In my imagination, this could be something like a dangerous like a fly-by.

This question is a different from this one, since the scenario in that question is when the pilots are cooperating but have some misunderstanding on when command is transferred to one from the other, or if one doesn't accept to receive command of the aircraft.


texts:
If you plan to fly on a cold morning and there is frost on the plane, what needs to be done?

Do you have to remove the frost from the windows? wings? tail? fuselage?
How should you remove a thick layer of frost?
Can you rub the frost until it's smooth and take off?


texts: Is it possible for one runway to have a different TORA in each direction?

texts: Is it possible that TORA is not the same for both directions on a single runway?


texts: Is it possible to use refrigeration technology to cool the skin of supersonic aircraft?

texts:
The fastest air breathing aircraft, the Blackbird SR71 flew at speeds above Mach 3.  Its engines could achieve much higher speeds but were limited by the aircraft's skin which would melt due to friction with the surrounding air should it fly faster.

Is it possible to use refrigeration technology to cool down the aircraft's skin so it can reach much higher speeds?


texts: How does the position of vortex generators on engine cowlings affect flight?

texts:
I know what vortex generators (VGs) do. My question is: How come some aircraft have VGs on both sides of the engine, whereas other aircraft have them on the inside only?

For example, in this picture of Boeing 737, a vortex generator is only on the inside of the engine:

On the contrary, the Airbus A319 has them on both sides:


texts: How can I use XFLR5 on a shape with no maximum thickness at one point?

texts:
I want to run an analysis with XFLR5 on a shape that is not really airfoil shape since it has no maximum thickness at one point only, it is basically like the shape below:

But when I run an analysis, the program keeps showing that at all angles it does not converge. Could the problem has to do with the XFLR not knowing the maximum thickness and at what position? or is there another possible reason?
Here are the coordinates of the shape:
http://www.filedropper.com/elipse


texts: Can flaps be used to perform rotation and flare?

texts:
TL; DR using flaps to directly control sink/climb rate near ground = simpler and faster response = easy to fly airplane?
Rotating is the pitch up during takeoff that causes the aircraft to leave the runway.
Flare is the pitch up just before touchdown that causes the sink rate to drop.
In both maneuvers, a downforce is applied to the tail, to re orient the aircraft to increase the angle of attack, so as to increase lift. The objective is this lift, rather than a change in orientation.
Hence, would it not make sense to use a method to directly alter lift, if available? Specifically, would it not make sense to increase the flap settings just for the moment these maneuvers are done? Takeoff is done at a non-maximum flap setting. When the airspeed nears the required value for liftoff, flaps could be lowered to full. Final approach can be done with takeoff flaps, and just above the runway, instead of pulling back, the flaps could be lowered.
I know the flaps are slow to deploy, but the moment of the fuselage makes pitching slow as well, doesn't it? Even if the slow movement of the flaps erodes any advantage in terms of response time, the decreased angle of attack at the leading edge would be favorable in terms of stall characteristics, wouldn't it? And the requirements to touch the main gear first on landing could be satisfied with even a relatively small pitch angle. And tail strikes could be avoided.


texts: Why can't a plane flying due west just hover in the air and wait for the destination country to arrive?

texts: Since the earth is rotating, why can't a plane that is flying from say, Perth to Johannesburg, just hover in the air and wait for Jo'burg to arrive underneath?


texts: Is induced drag not caused by tip vortices?

texts:
According to most online resources, including NASA, induced drag is caused by wingtip vortices which induce downwash. However, in StackExchange I have found a few answers (Peter's and Jan's) that actually drag caused by vortices is a myth and induced drag is a simple inherent reaction force (vortices and induced drag are both consequences of downwash, which itself is caused by lift creation).
Although this theory looks quite intuitive, I am still confused. Could anybody give me some links to more extensive research of this issue or explain which one theory is scientifically correct and why?


texts: What are the visual differences between the ATR42 and the ATR72?

texts: I tried to find the visual differences between the ATR42 and the ATR72. I downloaded some images from Google but I can't find any. Would you help me?


texts: Why would a fighter use the afterburner and air brakes at the same time?

texts: I was looking for air brake pictures on different fighters, and then I saw a Tornado using afterburner and air brake at the same time! Air brake duty is to reduce speed, isn't it? So why would a fighter burn so much fuel to increase thrust and then use speed brakes simultaneously?


texts: How to get IATA code for the Airline PSS system?

texts: If we are having airline PSS (passenger Service system) System, how can we registered with IATA and get IATA code. as an example Amadeus is using 1A, Sabre is using 1S, SITA is using XS etc..


texts: Can I maintain my IR currency from the right seat in a non "N" registered aircraft?

texts:
I completed my IFR checkride on the 15th of May this year, the next day I moved to Spain to study my EASA ATPL (airline transport pilot license).

A friend of mine here in Spain is doing his time building and I am allowed to sit in the right seat with him. Would I be allowed to log my approaches (66HIT) from the right seat even though I don't have an EASA PPL and the aircraft is registered in Spain?

I ask because that would save me the cost of paying for an instructor and a checkout flight as well as the hassle of flying alone in airspace which is completely new to me!


texts: How should a glider pilot handle inadvertently entering a foreign country?

texts:
Typically, when an aircraft lands on a different country than its departure, it has to land on an international airport. There many services are provided like customs, passport control etc, to make the entrance to the country legal.

But what happens on an unpowered aircraft? (i.e. sailplane, paraglider, hangglider etc).

These aircraft may be forced to cross a border and not be able to return but to the country of origin. Landing at an airport (let alone international), may not be possible. As an example consider a paraglider that is blown back to the lee side of a mountain.

These aircraft usually don't file a flight plan, they are not equipped with a transponder, may not have radios to communicate with ATC, and possibly may not be detected by radars.

How can the pilot make their arrival formal, their stay legal and eventually return to the origin country with out problems? Is there any law protecting pilots in such cases, or will they be treated as illegal immigrants?

In general, if this ever happen to someone, what is the first action they have to take, and who shall they contact?

Consider crossing an "unfriendly" border. A EU citizen getting from an EU country to another obviously will not have any problems. But visiting a country that a visa is needed, or that in general you are not allowed entrance seems more troublesome.


texts: Can helicopters have engines running while rotor blade stays stationary?

texts: So, I was skiing sometime ago, and unfortunately, another skier got injured. So, a heli was flown up to get the injured skier. The rotor blades were stationary, but I still heard some sort of engine like sound. Does anyone know any helicopters capable of doing this sort of thing?


texts: Can a dual-engine aircraft take off with only one engine?

texts: When a dual-engine aircraft (such as the B737, A320, A330, B777 or B787) has reached the point where it is too late to abort a take off, can it take off if one engine fails?


texts: Why do these tail-sitters not have bigger propellers in their main engine?

texts:
My attention was called to tail-sitter aircraft, like these two:

Convair XFV Pogo By No information - US Navy, Public Domain, Link

Lockheed XFV 1 Public Domain, Link

These aircraft land on their tails but transition to normal flight during cruise.

But what I want to know is, why are the propellers so small? Disk loading is a big part of efficiency. That's one reason why helicopter blades are so big. It is more efficient to accelerate a large mass of air to a slower velocity than a small mass of air to a faster velocity.

As far as I know, the disk loading factor is valid for propellers in horizontal cruising too.

So why aren't the propellers any bigger? They have plenty of room at the nose. No worries about ground clearance. I would think for a helicopter-like takeoff, this puts a lot more strain on the engine and thus efficiency would be even more important than usual.


texts: How does thrust reverser selection have a destabilising effect on the rudder and increase the lateral skidding tendency of the aircraft?

texts:
I was reading in the FCTM landing section normal procedures the below paragraph.

  The reversers have a destabilizing effect on the airflow around the
  rudder and thus decrease the efficiency of the rudder. Furthermore
  they create a side force, in case of a remaining crab angle, which
  increases the lateral skidding tendency of the aircraft.

Could someone please explain as to how this effects airflow over the rudder and increase the lateral skidding tendency of the aircraft?


texts: Are there aircraft with multiple inlets for a turbojet engine?

texts:
Are there aerial vehicles which have multiple inlets with air ducts (shaped in S-forn) , which all lead the air to one single turbojet engine?
I have not enough space to put just one inlet area on my vehicle, so I thought about using inlets, located at the sides.
I think it is really difficult to combine the air of all inlets so that there is a uniform air flow in front of the turbojet -  because I don't have much space inside my vehicle.
Besides, I think is is really challenging when it comes to some maneuvers, where the flow sometimes will not flow through one of these inlets.
What do you think and do you know any vehicle from history?


texts: Why don't we treat all takeoffs as short field in GA?

texts:
Depending on the airframe, there are a number of techniques to reduce the Take Off Distance required. For example, deploying flaps.

What advantage is there to NOT using short field take offs, even when runway length is sufficient? Surely it's always advantageous to require the minimal amount of runway, thereby adding a larger margin for error?


texts: Do airways with multiple numbers (e.g., J89-101) imply combined segments?

texts:
On SkyVector, I see many airways with 'multiple' names such as J16-36 or even J89-94-100-128. I can't find any information on how to interpret these names.

I'm guessing it's a convention to say that for some portion of the airways, J89 and J94 overlap - but presumably it's still valid to simply route along J94 including those shared segments?

Example near KORD


texts:
my question concerning the Comparisons between the ILS/ Baro-VNAV approaching system
from the view points of safety, technician ( infrastructure, installation,maintenance and ..eg) relation efficiency, capability, accuracy and functionality?

thanks to your good sides..
best regards


texts: What rotors would be best for atmospheric reentry?

texts:
What rotor blade set up would be the best for entering Earth atmosphere or to shed speed before landing in place of a parachute?

I understand that the longer blades are more efficient, but are not as strong.
The link below explains how this might be used.

https://space.stackexchange.com/questions/35699/could-a-rotary-rocket-charge-a-super-capacitor-while-descending-on-mars's

https://commons.erau.edu/cgi/viewcontent.cgi?article=1283&context=discovery-day

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


texts: What is the longest distance at which an aircraft can be visually identified?

texts:
In the IL-2 flight simulator, when you turn on "markers" for planes you can see a belligerent side, the aircraft belongs to, at a distance up to 6km (3.75 miles) as well as its type with a tail number.

But in some books I've read mentions that pilots were able to see an aircraft number, its specific painting/livery etc. of other aircraft they encountered.

So I wonder: in real life, at what distance can such things can be distinguished by a pilot with good sight (I understand that this depends on the size of an aircraft)?


texts: What are the ICAO PANS? What are their contents?

texts: There are how many I.C.A.O. PANS? What are their basic contents? I have tried a lot in internet, but could not find out.


texts: Should reliance on Auto-Flight Systems continue to increase in favor of manual flying skills?

texts:
In recent years there has been ongoing debate as to whether or not increased reliance on auto-flight systems (autopilot, auto-thrust, etc.) in favor of manual flying proficiency has had a negative impact on safety.

Are there any data or objective examples supporting either position?


texts: Why could increases in cockpit voice and image recording potentially raise privacy concerns?

texts:
A major concern someone or other brings up against practically every suggestion to broaden the uses of cockpit voice recordings or add cockpit image/video recorders to the mix (both of these, especially the latter, being actions that accident investigators have long urged regulatory agencies and aircraft operators to implement in the name of air safety, and which the regulators and the operators have, for just as long, worked to weasel out of), and one which dates right back to when CVRs were first introduced, is that doing so would supposedly be a violation of the pilots' privacy.1

This concern seems somewhat misplaced:

For pilots operating commercially (including those operating the vast majority of the flights that would fall under the aforementioned proposed recording-expansion mandates), the cockpit is their workplace and the aircraft an item of company equipment, and there has generally never been any expectation of privacy for workers in the workplace while on duty, especially not as regards the use of company-owned equipment.3
For general-aviation pilots, the only time when they would be required to turn the recorded data over to anyone would be following an accident or incident, when the pilot(s) would have little reason (and, depending on the nature of the occurrence, may have been definitively rendered unable) to object to handing the data over.

Where, then, is the justification for these alleged concerns?

1: Other excuses offered for not installing cockpit image recorders are the large amounts of oh-so-expensive storage required to record and store cockpit video (which most likely stopped being a valid concern in the early 1970s, with the advent of miniaturised videotape systems with recording lengths of up to an hour - twice the length of contemporary CVRs! - and is a frankly ridiculous argument to make nowadays, when a tebibyte of solid-state flash memory, enough for dozens to hundreds of hours of high-res cockpit video from multiple vantage points, can be had for less than a hundred bucks in a package the size of a candy bar2), and the supposed uselessness of recorded image data for accident-investigation purposes (a contention easily refuted by a cursory glance at the many accidents and incidents that have prompted accident investigators to repeatedly and consistently urge for the installation of CIRs, as well as by five minutes’ or so thought about all the things that could be useful to an accident investigation and which would show up on a video recording, but not - or, at least, not identifiably - on an audio recording).

2: In fact, the storage for a CIR would probably be less expensive than that in a consumer-grade SSD, as flight recorders, which record data in strict sequential order and where data recoverability is far more critical than data access control, would not use the complex encryption and wear-levelling circuitry found in most consumer flash devices.

3: This is why (for example) it is both legal and ubiquitous for companies to install software on their work computers to remotely monitor what their employees are doing on said computers.


texts: Did any Boeing 787 operator achieve the 20% fuel efficiency improvement over the 767?

texts:
Is there any airline which are able to get the complete 20% fuel efficiency on their 787 with respect to 767 it is going to replace, as told by Boeing.

I have read that one of the early customer like Air India are not able to get even 15% of fuel efficiency on their Dreamliners.


texts: What is the distance between RLLS lights?

texts: I've looked everywhere for a few days now, but I can't seem to find the distance between lights on an RLLS approach lighting system. The specific one I am looking at is for the 31C approach at KMDW.


texts: Which gas is used to fill the evacuation slides of modern aircraft?

texts: We have seen that after an emergency landing when the airplane needs to be evacuated promptly, evacuation slides get deployed immediately. I am not sure if normal air is being inflated in those slides or do they use some other gas in them?


texts: Declaring an emergency: How should you report fuel remaining?

texts:
When a flight has to declare an emergency, they are asked for souls on board and fuel remaining. Sometimes the ATC will want fuel in minutes (or hours) and sometimes in pounds.

Could we get a description of why there is no standard for the fuel remaining description? In other words, why sometimes time remaining and other times weight?

(NOTE: I've tagged this FAA-regulations, because I mostly listen to RealATC, or variants, of US ATC, but this question shouldn't be limited to FAA Regs)


texts: What is the difference between COM and Auxilary COM signals?

texts: when the aircraft navigation system is tuned to VHF COM frequency (118-137.990MHz) then COM receiver will able to receive two types of signals one is COM signal and the other is AUX COM signal what is the difference between them ?


texts: Unmanned Drone vs Conventional Manned Fighter in Combat: How realistic?

texts:
How far are we / Is it even viable to think of a scenario where a drone gets employed to counter a conventional manned fighter?

I can see several benefits:

Free of the G-restrictions of a human the drone is free to undergo far more severe manouveres
Cheaper testing costs since a drone crash isn't as expensive / as unpalatable as the death of a test pilot
More risk appetite during actual combat since a human life is not at stake
The removal of the cockpit and life support / protective systems (e.g. No O2 tanks / No pressurization / No ejector seats) leading to a weight reduction, performance improvement and design flexibility. Perhaps allowing greater munitions loads etc.
The possibility of undertaking some version of suicidal yet mutually destructive manouveres that are out of question in conventional dogfights.

On the other hand, several limitations I can think of:

Poorer field of vision & situational awareness of a remote drone operator operating via cameras and sensors
The lag between control and reaction inherent to today's drone remote operator systems. Though how much of this could be improved via better technology is a crucial question. The current generation seems to use Ku band satellite signals. Could some form of ground network (but beyond enemy reach) provide more responsive controls? How close have we approached the fundamental physics latency limits even with existing satellite transmission technology.

As a totally different alternative, is the possibility of an unmanned, autonomous drone realistic? How far are we on the AI / sensors side where a autonomous decision engine can realistically be a good match for a human adversary in a dogfight. The autonomous option would make the control lag issue redundant.  (Redacted to focus the question on manned drones)


texts: What is the lowest RNP approach requirement without being RNP AR?

texts:
I was recently told by a friend that as soon as RNP for an approach is below the 1.0/0.3nm standard that it is required to be RNP AR.

At least here in Australia, a curved segment anywhere on the approach will qualify it as RNP AR, even if the RNP is 1.0/0.3nm.

Is there a hard and fast rule for RNP AR?


texts:
Whenever I hear anyone talking about P-Factor, (whether it be single-engine left turning tendencies or multi-engine loss of directional control scenarios), someone always brings up the fact that the descending blade of a propeller generates more thrust than the ascending blade.  I'm wondering why that's the case.

What is P-Factor and why does it occur?


texts: Why are aircraft external lights round, not tear-drop shaped?

texts:
I saw this image of a Cessna 172's tail posted on another question and it made me wonder why the beacon light is basically a cylinder, and not a more aerodynamic, teardrop shape?

Image source


texts: When airplanes first got windows, what material was used?

texts: When airplanes were first introduced they were open cockpit - but soon enclosed cockpits were developed. What were the first materials in use for airplane windows? I don't believe plexiglass existed back then.


texts: How much safer does painting prop tips make a plane?

texts: While re-reading one of my earlier questions, the answers left me wondering how much good painted tips on props actually does.  I did some searching for statistics but didn't come up with much.  Are there any published statistics about how much safer it is to have painted prop tips specifically in military planes (although civil aviation stats would also be nice)?


texts: How does wake turbulence affect parachutists?

texts:
If one were to parachute out of a jumbo jetliner, would wake turbulence from the plane be an issue?

A 747 for instance produces much more wake turbulence than the smaller planes usually used to drop parachutists. Would that make a difference, or does the trajectory of a parachutist stay clear of wake turbulence in any case?


texts: How close to a Restricted Area can a pilot be cleared to fly?

texts:
In my local area there is an instrument approach that skirts the edge of a restricted area by a mile or two. The TRACON for this approach is not the controlling agency for the restricted area. When the restricted area is active, the TRACON will not give clearance for the instrument approach unless the weather is VMC. Is there a requirement that ATC cannot have pilots flying too close to Prohibited/Restricted areas in IMC? Even if they're flying a published procedure?
Is this different for VFR flights?


texts: Which way should you turn to avoid another aircraft?

texts:
During visual flight conditions, when you see another aircraft in your path, you should strive to avoid hitting it.

In shipping there are standard international rules about which way boats should turn in order to avoid each other.

Are there similar rules in aviation?


texts: Is the Batjet Design Physically Feasible?

texts:
I realize the plane is fictional. However, in the Batman Animated Series by Warner Bros, we see this Batjet.

So this got me thinking (and I'm not a physicist): is this air frame configuration even possible? Has a "rounded", forward-swept wing design like this been attempted before? Or would a design like this never actually fly?
Any real-world examples that are similar in nature?


texts: Does rolling affect the thrust of a propeller?

texts: If a plane with a propeller, e.g., a Spitfire, does a constant barrel roll in the same direction as the propeller, will the plane travel faster as impractical?


texts: Does the pressure at the static ports drop as the aircraft's speed increases?

texts:
This answer by Tyler Durden explains what static ports are and how they work:

  The "static ports" allow air into the instrument to provide the input for the air pressure on the side of the aircraft. They are called "static" ports because in general they take in air at the ambient pressure which does not change very much [...]

Currently, the answer has a comment by Zeiss Ikon which states:

  In fact, the pressure at the static ports will drop as the aircraft's speed increases (Bernoulli principle) [...]

Is this true? If I'm flying at a constant altitude, will the pressure at the static ports decrease as I speed up and increase as I slow down?

If so, does the altimeter have a mechanism for compensating for this?


texts: Why don't combat aircraft have rear-facing weapons?

texts:
This excellent question addresses the role of dogfighting in modern aerial warfare. However it seems that most ACM concentrate on maneuvering into shooting position. Why don't combat aircraft have rear-facing weaponry?

Even WW-II bombers had rear-, side-, and downward cannons, albeit manned. Could a small electronically-controlled cannon be added to the stern dorsal part of a combat aircraft, for shooting rearward? I've personally seen remote-operated FN MAGS on vehicles, the whole system seems to weigh on the order of 100-150 KG including hundreds of rounds. The vehicle-mounted systems took up about a cubic meter or so of space, but a purposed-designed system could probably take up less than half that, and probably shave off a good portion of the weight as well.

Could a computer not point a barrel at a vehicle with a relative velocity approaching 0 and shoot, even in a +Mach 1 wind in the direction of the target? It may be enough to just get a few bullets in, shotgun style. The Uzi rifles famously don't shoot straight, they make a cone of bullets. Perhaps this cone, if aimed in the general direction of an aggressive aircraft, might be enough to either disable it or get it off your tail. A short barrel will make a wider cone, perhaps the rear-facing weapon could have an very short barrel. ACMs such as the Cobra maneuver seem to imply that there are a finite number of angles from which attack is most likely, the weapon could be limited in angular range to those angles.

I'm sure that piloting an aircraft while trying to avoid being shot is difficult enough, so I wouldn't assume that such a system would be of much help on a single-seat aircraft. However, in a dogfight presumably the ROI or navigator could operate the guns while the pilot does the aviation.


texts: Why was the production of the Lockheed SR-71 Blackbird halted?

texts: Why was production of Lockheed's SR-71 Blackbird halted, given that it was an advanced supersonic jet that was ahead of its time?


texts: Are there aircraft that fly without fuel or electricity?

texts:
I was browsing through Wikipedia when I saw this:

  An electric aircraft is an aircraft powered by electric motors. Electricity may be supplied by a variety of methods including batteries, ground power cables, solar cells, ultracapacitors, fuel cells and power beaming.

This led me to wonder whether an aircraft could stay airborne/take off without fuel or electricity. (Other than gliders)


texts: What prevents a government from selling/leasing publicly owned airports?

texts:
When an airport is open to the public, it is generally owned and operated by a government entity. If the local government leases or sells the airport, this would generate significant amounts of revenue.

What are the legal impediments which discourage a local government (who owns a public airport) from leasing or selling their airport to a private entity?


texts: Can single engine planes glide from a falling position?

texts:
Near the end of the 50s Sci-Fi movie This Island Earth, the protagonist is escaping from a flying saucer which is crashing to Earth. As he was abducted while flying a plane (specifically a Stinson 108-1), it's sitting in the cargo hold on top of a retracting hatch:

The protagonists then start up the propeller, and once it gets up to speed, the entire hatch seems to disappear and they're dropped vertically out of the bottom of the flying saucer:

They then manage to continue moving straight without going into any kind of dive, before banking out of the shot.

Is this even remotely possible? I would have assumed that when they leave the system of the flying saucer, they will lose the speed which the saucer has and will basically be falling in a stationary position as they have no lift due to the air only hitting the bottom of the wings.


texts: How does the airline decide how many meals to load aboard a flight?

texts: I've researched a bit, and found that entire load of meals may be discarded if a flight is delayed. I've also seen some posts that say first/business class meals are stocked at 110% of capacity. Additionally, some posts say that meals are based on the actual passenger count, rather than the seat count. I'm curious as to the actual practice for determining how many meals make it aboard a commercial flight.


texts: What does the suction gauge actually show?

texts:
If I recall correctly correctly the vacuum suction gauge in the TB10 has a scale from 3 to 6, with the green range being 4 to 5 (I might slightly off on those numbers though).

It's clearly marked as showing inHg, but unlike the manifold gauge it's on the lower stop when the engine isn't running (rather than the upper stop if, as the manifold gauge, trying to reach ambient pressure). I haven't really paid attention to it's behavior in the aircraft (only checking that it's in the green), and I just looked at it in Xplane right now which might be wrong of course.

Is it showing the negative difference to ambient pressure? Or the difference in pressure before and after the vacuum pump (which may or may not be the same thing)? Or something else completely? :)


texts: why does it cost so much just for an hour of training?

texts: I'm currently in the process of becoming a pilot and the question I keep asking myself is why does it cost so much for just one hour?


texts: Is the "Bay Tour" flight path documented, or is it a more informal route? Are there similar flight paths for other cities?

texts: During my Private Pilot's Licence days out in San Francisco, we often flew a "Bay Tour": a sightseeing flight northbound from San Jose through SFO's Class B , over the city and Golden Gate Bridge, then east to Oakland and south to return to SJC. Local approach controllers were familiar with this route, and a pilot could file a flight plan for a Bay Tour with everyone knowing what he was talking about. In addition, the tower at SFO would often go out of their way to give aircraft on a Bay Tour a better view of A380's and 787's out of SFO. However, I can't find any official information on it. Is it a published procedure, or just something that everyone out there has come to know about? Do similar flight plans exist for other cities and if so, where can I find information on them?


texts: Could I, as a passenger, get a picture with the pilots in the cockpit before takeoff/after landing? I'm asking specifically about any rules that would deny a passenger into the cockpit. I know this is too broad and subject to change from airline to airline, but generally would I be allowed? What about domestic vs international flights?


texts: Which are more efficient in putting out wildfires: planes or helicopters?

texts:
A lake is near where both helicopter and plane can access the water and fire.

Which aircraft (if you had access to only one) is more efficient in putting out wildfires? Which aircraft is preferred to fly for this? What cost less to operate and which aircraft can deliver the most water per load and on the average?

I have added this link below on how this airplane delivers water. Sorry it is longer than 4 minutes. In the video at 4:49 the plane can touch down and refill without stopping.


texts: Is the Reynolds number the same for both the airfoil and wing? If not, why/how does it change?

texts: This question might be stupid, but I don't understand this one thing: does the Reynolds number change when you go from the airfoil to the wing? Or is it the same for both?


texts: Do you need to put your wings at the center of gravity when building an airplane?

texts: I have been wondering about this for quite a while and can't find an answer.


texts: Do different planes (category) aim differently in the 'final stages before flaring'?

texts:
(youtube.com)

Do different planes (categories A through D) aim differently in the final stages before flaring? I'm asking about precision runways.

The reasons I ask:

An ILS' glide slope is not coincident with the PAPI for example (when does the shift from G/S to PAPI occur?)
There may be differences in the touchdown zone markings
Airplanes come in different cockpit heights and approach speeds.

By 'final stages before flaring', I mean when the landing is manually flown in VMC, when the shift from looking down to up occurs.

Example: you may be on the G/S but off the PAPI when you look up, which one do you follow based on the category?

There is plenty of anecdotal information all over the internet, so I'm looking for as factual an answer(s) as possible based on experience. This post for example (pprune.org) offers contradicting advice, one quotes a document saying, "PAPI provides guidance down to flare initiation," and mostly others saying to ignore the PAPI.


texts: Since shock waves have non-negligible viscosity, why do the normal shock relations ignore friction/viscosity?

texts:
The normal shock relations (seen below) are derived by using steady, 1D, neglect potential, no shaft work, adiabatic and zero viscosity assumption. However, since shock waves are "thin regions of high velocity and temperature gradients, where, friction and thermal conduction play an important role," (Anderson, Fundamentals of Aerodynamics) why is the assumption of zero viscosity correct?

While I know that the normal shock relations give the correct answer, I am unsure of why neglecting friction is justified and does not lead to inaccuracies.


texts: Sensitivity of aircraft stability with respect to the CG location

texts:
I am working on the design of an aircraft (2 m long, wingspan = 3 m). The platform is longitudinally stable but it is very sensitive to the variation in CG location. For example,
1) CG_location = 100 mm from wing L.E, the static margin is about 15% of MAC.
2) CG_location = 105 mm from wing L.E, the static margin is about 8% of MAC.
3) CG_location = 110 mm from wing L.E, the static margin is about -1% of MAC. (Unstable: Cm vs Alpha curve slope becomes positive)

So, effectively while manufacturing the aircraft or while dropping the payload the CG of my aircraft should not vary more than 1 cm, otherwise it would become completely unstable. Taking into any manufacturing errors, the platform CG might not be exactly as expected and hence having such a small margin creates issues.

How should I deal with this issue? Can I have any suggestions on how do decrease the sensitivity of the longitudinal stability to the CG location? Thanks in advance.


texts: Are there any duty time limitations on ferry pilots?

texts: What FAA regulations are in force when a commercial pilot is being compensated to ferry a newly purchased aircraft?  Is there a limit on duty time?


texts: How much is the Boeing 787 Dreamliner affected by teething troubles now, one year after commencing commercial operations?

texts: Boeing's Dreamliners have been hit several times by small bugs, like fires in the batteries or other engineering issues. Are such incidents frequent when new types are introduced, and how much has the situation improved one year later?


texts: What does performance speed refers to? Aircraft performance in general

texts:
For example C172R specifications:
Cruise speed:122 knots
What does this mean?
Maximum achievable Indicated airspeed At specific conditions?
Another example - rate of climb: 721 ft/min
For what conditions? So much factors can affect this..


texts: What is the drag optimized wing form for given lift and bending moment?

texts:
I am trying to build a passive hydrofoil board.

Something like this:

I want to use wood and i am coming to the conclusion that i want to optimize drag for a given lift and bending moment.

Doing my research i found out that an elliptical wing isnt the best approach.
But a linear tapered wing should work better.
Is there a rough formula for this optimization?

I already came across two articles:
"Lift Distributions for Minimum Induced Drag with Generalized Bending Moment Constraints" and
"THE SPANWISE DISTRIBUTION OF LIFT FOR MINIMUM
INDUCED DRAG OF WINGS HAVING A GIVEN LIFT AND
A GIVEN BENDING MOMENT"

I only need a rough formula/shape


texts: Are there any speed and altitude limitations on the autopilot?

texts:
This comes from a flight simulator experiment ages ago in the Boeing 737....

  I'm on the runway. I engage the heading switch, followed by the altitude and thrust. The aircraft lifts off, although hardly in a clean rotation.

Now I'm wondering: While it did work in the flight simulator, will the autopilot follow these commands in real life as well if I  repeated this in a business or commercial jet?

Is there anything stopping the autopilot from engaging a specified altitude or from following instructions which are utter nonsense?


texts: What is the reapplication process for a suspended dispatcher certificate?

texts:
I had my dispatcher certificate suspended for a year for leaving the testing site before I could provide an adequate urine sample.

I did not realize this was a reportable event. I accept the suspension but am looking for the process to follow to get reinstated after the 1 year period.


texts: How does the FAA decide if a PPL applicant with ADHD can fly?

texts:
For the past few years, I've been struggling with fidgeting, difficulty spending long periods of time on creative tasks, difficulty finishing long and complicated tasks, and a few other symptoms. These are difficult in my professional life as I'm a journalist, so long periods of time doing research and writing is a necessary part of the process. My physician mentioned ADD/ADHD as something to look into, with potential benefit if treated with medication.
The trouble is, I'm also looking into getting my PPL next year, and I noticed that the FAA outright bans a number of ADHD medications, and seems to have a whole extra evaluation process you have to go through if you get diagnosed with ADHD. Nowhere could I find a good explanation of what this means if you're considering getting ADHD treatment but you also love, love, love to fly.
What is the FAA's policy, specifically covering PPL medicals for those being treated for ADHD?


texts: Why is this missile positioned in this odd position? How can it be launched correctly?

texts: How this missile is positioned here in this odd position? How this can be launched right from this jet?


texts: What is the advantage of increasing an aircraft's horizontal tail surface area?

texts: Most aircraft have horizontal tails. What is the advantage of increasing the horizontal tail surface area?


texts: What is this hole at the front of the engine pylon on a Boeing 707?

texts:
Images of the Boeing 707 show a hole at the front of the engine pylon just above the engine.

Can someone please tell me what is the purpose?

Also why do images show the hole absent on the left outer engine pylon but present on engines 2, 3 and 4?

ref: wikimedia commons


texts: Why does the FAA mandate a temperature indicator for all manned balloons?

texts:
14CFR31.85 ("Required Basic Equipment" for manned free-air balloons) requires an Envelope Temperature Indicator (ETI). This is a requirement of the FAA, not necessarily the manufacturer. Some balloon Flight Manuals do not even mention an ETI.

My question is, is there somewhere that explains why the FAA mandated a ETI for all hot air balloons, and how it's used with regard to the determination of load, overheating and gross lift with a hot-air balloon? (Might be more than one question! ;-))

There does not seem to be an industry standard, and the temperature inside a HAB is critical to flight performance and safety.
Best regards,
FFG


texts: I was reading 14 CFR 23.3, which discusses airplane categories. In normal and commuter categories, stalls (except whip stalls) are allowed. The regulation, however does not define "whip stalls." What is meant by this term?


texts: Why does the A320 still have this old fashioned nose?

texts:
Another answer stated that Airbus was less focused on just brand image, and more on aerodynamics, explaining the more rounded nose of it's 320 vs the 737's. But it still has flat cockpit panes which very conspicously NOT flush with the nose.

The same cannot be said of the A220, which is not much smaller, or even of the A350 which Airbus themselves developed.


texts: Would an aircraft with no ailerons, no elevators and no rudders be safely flyable?

texts:
With contrarotative propeller (or not, if twin engine), cyclic and collective blade control.

Would such an aircraft be safely flyable, and how efficient would it be, assuming it can have perfectly smooth wings (and tailplane)?

In case of engine stop (allowing axle free spin and control on blades), could it control its glide and land on the runway, with the propeller's blades in an almost feathered autorotation configuration, allowing attitude control and minimum disk drag?

(like autorotating one reversed Kamov on its rotor-head, in a skydiving wind tunnel blowing a bit slower than terminal velocity)

Edit: If it goes twin engine and tailless (and still controlesurfaceless) how active cyclic pitch control would be necessary to allow use of non-reflex wing's airfoil?

Edit2:
Switch from thrust + attitude control mode, to no-thrust + attitude control "reversed autorotation" mode.
Reversed rotation allows most efficient use of blade's airfoil camber.


texts: How do aircraft batteries power the engine/APU?

texts: I fail to understand how do batteries power up the jet engines/APU. Are they responsible for starting up the Ignition that ignites the air-fuel mixture? Or is there some other function which I'm missing out?


texts: How is device control software checked for quality?

texts:
Many, many reports on the now infamous MCAS suggest a software patch is forthcoming in the next several weeks that will address the confounding single point of failure with the two AOA sensors that probably contributed to at least one 737 MAX crash.

As a software developer (of a much different variety than a Boeing engineer), I am very curious:

What do regulators and the public know about the actual code that flies planes (and sometimes crashes them)?

I've been looking for an hour and can't locate a single patent application that even mentions what language it's written in, though I imagine it's a complex network of machine languages and so forth. I tend to doubt the 737 runs on JavaScript...

More importantly:

Is there any procedure for QA'ing an airline manufacturer's code?
Does someone at the FAA get invited to Boeing's private Github account?

I'm mostly being facetious, but you get the idea. I ask because every day it sounds more and more like a freshman error in code cost 300+ lives.

Is there anywhere I can look for descriptions of this mysterious code and its forthcoming patch?


texts: What procedures will cockpit crew follow during a sudden depressurization?

texts:
When pilots face a sudden depressurization, they will follow some procedures.
What are their sequences and if there is any addressed to the cabin crew?


texts: Who has more power? Air Force One PIC or ICAO or FAA?

texts: So, ICAO(or FAA) Controls everything in the air, but is Air Force One on top of it, or does Air Force One need to follow the ICAO's (or FAA's) regulations?


texts: Why is vortex state impossible in autorotation?

texts:
An article at Skybrary states that for a vortex ring state to occur:

  The aircraft has to be in powered flight. If the engines are not producing power, the aircraft is in autorotation and the upflow of air (rather than engine power) is being used to drive the rotor motion. It is not possible to enter the vortex ring state whilst the helicopter is in autorotation. [emphasis mine]

The FAA Rotorcraft Flying Handbook.pdf lists autorotation as a method of getting out of VRS.

  In a fully developed vortex ring state, the only recovery may be to enter autorotation to break the vortex ring state.

Why is a VRS impossible during autorotation?


texts: How does bleed air maintain pressure for pressurization after being cooled?

texts:
I found on aerosavvy.com/aircraft-pressurization the paragraph below, which talks about bleed air on airliners:

  Most modern airliners use bleed air from the compressor section of the engines to pressurize the cabin. This very hot air must be cooled to a comfortable temperature before it’s directed into the cabin.

If it is cooled too much it wouldn't be under high pressure, right?

The cabin needs high pressure air because the air at 30,000ft is at too low of a pressure, so they need to simulate a 6000-8000 feet pressure. This bleed air is very hot high pressure air, I understand you have to cool it because it is way too hot for anything to operate with it.

But if you cool it, doesn't it lose pressure, so it would be low pressure air which is not what we want? I don't know where I am getting confused at.


texts: Are there limits to speeds at certain altitudes?

texts: Are there speeds that cannot be exceeded at certain altitudes?


texts: What is the rod attached to the top of the Bell UH-1N's rotors?

texts:
So, I was looking at an image of a Bell UH-1N, and noticed that the top if the rotor has a little stick or rod
What is this rod for? I also see this rod on a RC helicopter.


texts: Why stirring the cyclic helps in stuck left pedal?

texts:
In demonstrating stuck left pedal from a takeoff with my instructor yesterday when starting a nose left turn he had me stir or move the cyclic clockwise in small steady circles and pump the collective. It did slow the spin down significantly but I just don't understand why.

Any thoughts or comments would be greatly appreciated.


texts: What factors lead to mounting engines towards the rear of aircraft

texts:
Some aircraft have engine beneath the wings and some have at the rear of the aircraft.

What are the factors that are considered while deciding where to mount an engine?

Is one configuration advantageous over other?


texts: Is it okay to purposely stall a small single-engine aircraft just before touch down to get a good flare?

texts:
I'm still learning ground theory and have only flown in simulators (P3D v3 Academic). For a long time, I've been trying to properly flare single engine aircraft but have mostly failed. I even watched a video on youtube made by a certain flight instructor that said that the smaller airplanes like a Cessna 172 and Mooney acclaim don't flare - they "transition" just to make sure the rear gears touch down first.

However, I recently invented/discovered a trick that let me get a nice flared touch down while flying one of these aircraft (in P3D): as I approached the runway, I had the nose pointed down (or straight, as required) but as I was about to reach the threshold, with my speed somewhere around 50 knots, I reduced the speed (sometimes almost pulling the throttle to IDLE) and pitched up. In that condition, the airplane would tend to fall rather than go up and since the aircraft's height is just around 20 - 50 FT, the impact, I thought, would not be fatal.

However, I realized that I was essentially stalling the aircraft (purposely) and I even got a stall warning (though it obviously lasted for about 3 secs). And note: since I'm saying "STALL", I mean to say that the aircraft does cover some (significant) horizontal distance stalling before touching down. I know it's obvious to let the airplane sink a little by synchronizing the thrust and pitch but what i am talking about here is essentially something like a "flared approach", a nose-up approach like what usually jet airliners do.

As far as I know, a stall situation is usually a bad one. However, I was thinking that it might be okay if the pilot knew what he/she was doing and still had control while purposely stalling the aircraft. But I'm confused since I haven't flown a real bird yet.

So, my question is, is it okay to stall a small aircraft for the sake of a good flare?


texts: Why do people put $1 & OVC on aircraft bills of sale?

texts:
When purchasing an aircraft a bill of sale is created to show transfer of ownership from the seller to the buyer. Bills of sale include what the seller was paid in exchange for the plane. But apparently bills of sale for aircraft are commonly done differently.

  The first item to fill in is the price of the aircraft, where it says "For and in consideration of $___." To preserve the confidentiality of the transaction, the FAA will accept the phrase “$1 & OVC” (Other Valuable Considerations) in this spot, and most Bills of Sale are filled out in this fashion.
  source

At first I thought maybe it was some way to get out of sales or use tax, but the FAA would certainly not approve tax evasion. The state will calculate taxes either from the lien amount or the usual market value. This would definitely not pass muster for the sale of a car or a house. The only time the state treasurer ever had me put $1 was when I was giving a car to a family member.

Obviously the price is being withheld for some reason, but I can't really figure out what that reason is. The price is easily found with a records search. The only person this hides the sale price from is the FAA. And since the FAA approves that wording they obviously don't care. Why do people not want the FAA to know how much they paid for their plane?


texts: Does increased fineness ratio decrease skin friction drag?

texts:
From the Wikipedia article on parasitic drag:

a designer can consider the fineness ratio, which is the length of the aircraft divided by its diameter at the widest point (L/D). It is mostly kept 6:1 for subsonic flows. Increase in length increases Reynolds number. With Reynolds no. in the denominator for skin friction coefficient's relation, as its value is increased (in laminar range), total friction drag is reduced.

The higher fineness ratio gives a longer flowpath, slowing the air more (=higher Reynolds). A slower boundary layer creates less friction downstream.

But increasing the fineness ratio increases the total surface area as well. And that is a recipe for increased friction. From the Wikipedia article on fineness ratio:

As the name implies, this is drag caused by the interaction of the airflow with the aircraft's skin. To minimize this drag, the aircraft should be designed to minimize the exposed skin area, or "wetted surface"

So, what am I missing?


texts: How does a 'Highly Swept leading-edge' delta wing reduces fuel burn and increases range?

texts:
Spike Aerospace  claims to have designed an aircraft called S-512, with maximum speed of 1.8 mach and cruise speed of 1.6 mach, speaking about the notable changes in the aircraft, Spike Aerospace says:

  “The new delta wing of the S-512 delivers high aerodynamic efficiency and improved flight performance in both low-speed flight and supersonic cruise,” “The highly swept leading-edge reduces wave drag and consequently reduces fuel burn and increases range.

How does a highly swept leading-edge helps?


texts: How strong would a servo motor need to be to power the control surfaces of a fixed wing ultralight aircraft?

texts:
I'm looking to build an ultralight aircraft.

The video above shows a good example of how one is controlled with wires or with metal fulcrums/levers, but I am interested if they can be controlled electronically.

My idea of this is that it would work exactly like an R/C plane, but instead of being controlled with a radio, it will be controlled with a joystick through a wired or wireless signal.

I saw the other post that talked about a wireless fly-by-wire system and they said it could be unreliable, but that's not exactly what I'm wondering. I want to know how I can get the supplies to do it and look at the options.

How strong do the servos need to be for such an application? Obviously the rudder, elevators and ailerons will be light, but not as light as an RC plane's, so I can't use servos from a local hobby shop.


texts: Is there an abnormal condition that could have caused this fatal accident involving a stall?

texts:
In 2009, a Grob 103 glider stalled and crashed at Richmond Field, Michigan, killing the passenger but not the pilot. (NTSB accident report: CEN09LA353)

The accident occurred after a failed winch launch; during the winch launch, the tow cable broke while the glider was about 400 feet AGL. The pilot correctly decided to turn around and return to the airport.

Here's what happened next, according to a statement the pilot later gave:

  I could feel in the controls that something was not right and the glider was not responding in the manner that I am accustomed. There were none of the signs of a stall and the glider did not behave like it has any time that I have practiced stalls. Before I could determine the cause or take any action, the nose abruptly dropped and we dove toward the intended runway.

The NTSB report about the accident states that the probable cause of the accident was simply the pilot's failure to maintain adequate airspeed, resulting in a stall. Judging by this, the NTSB didn't seem to put much stock in the pilot's report that "something was not right".

Suppose that we take the pilot at their word, however. Is there any type of abnormal condition that might have caused a "feeling in the controls that something is not right", and which could cause the nose to drop with "none of the signs of a stall" occurring beforehand?


texts: Which FARs does the Boeing 737 MAX conform to with respect to turbulence?

texts: Based on this question/answer it seems that the FARs in relation to turbulence handling have been updated several times over the years. Does the Boeing 737 MAX conform to the latest FARs or to the FARs in place when the Boeing 737 was first certified?


texts: Is it legal to carry medical oxygen on an aircraft for a passenger?

texts:
If a passenger shows up with an oxygen tank, can they bring it with them on the flight if their doctor says that it is medically necessary, or is a compressed tank of air considered hazardous material?

What are the regulations that cover this for flights operated under Part 91 and Part 135?


texts: Which procedures or devices do ensure the aircraft stop flying after the pilot has ejected?

texts:
Pilots eject from aircraft when it cannot be controlled any more. Ejection seems to happen without delay and few time to secure the aircraft and its weapons.

Pilot ejection, source.

Thanks to @RonBeyer for pointing out the Cornfield Bomber which also links to a notable accident in 1989 with a MiG-23 flying 900 km and several countries, uncontrolled:

  During takeoff [from Poland], the afterburner failed and the engine
  began losing power. At an altitude of 150 meters and descending, the
  pilot assumed he had a complete engine failure and ejected. [...]
  After flying over 900 km (560 mi) the MiG crashed into a house,
  killing a Belgian teenager.

What are the procedures or features in place to prevent the aircraft to keep flying and explosives to explode?


texts:
Does True Air Speed (TAS) change with wind speed and direction?

My understanding is that if an aircraft were travelling at 470kt TAS, with a hundred knot tailwind, the ground speed would be 570kt. In this case the TAS would remain the same, regardless of the wind, but the ground speed would change.


texts: Why do swept wings decrease the drag increase that occurs in transonic flows?

texts:
Swept wings are used in aircraft that fly in the transonic regime because they 1) delay the critical Mach number 2) reduce the drag increase that occurs (smaller drag divergence).

I am trying to understand physically why a lower drag is observed. A common explanation is that only a component of the free stream is perturbed by the wing (see: Why are swept wings better for breaking the sound barrier?), but this does not explain why there is a lower drag when shocks do occur over the wing.

More specifically, I understand why the curve below shifts to the right as sweep increases, but want to know why the drag is not as high.

Source: https://history.nasa.gov/SP-468/ch10-4.htm


texts: How does a commercial airliner measure its weight/mass?

texts:
Other questions currently being answered cover situations regarding planes near, at or even above their MTOW. It raises a more basic question: how is the exact "ramp weight" of an airliner measured or estimated?

On most airlines, luggage is weighed and counted, so the pilot would know within 100lbs or so how much mass is in his cargo hold. He'd also know the "operating empty weight" of the plane itself (the weight of the airframe, all fluids besides usable fuel and the weight of the crew), and the mass of the fuel he's taking on.

The biggest variable, then, is the weight of the passengers and their carryons/personal effects. Last time I flew, I wasn't knowingly weighed and neither was anyone else getting on with me. So, while you know the number of passengers, the total "cabin weight" is a big unknown.

So, do planes have load sensors in their gear which could be used to exactly measure the plane's ramp weight? Or is a median passenger and carryon weight used, with a more conservative total passenger rating used in case a few planeloads err on the heavy side of the bell curve?


texts:
A recurring theme I come across is how, in an emergency, it is safer for a passenger craft (such as an Airbus) to try to land on the ground rather than at sea. My understanding is that the main reason for this is that at the high speed at which the plane would be travelling, landing in the sea would be like hitting concrete and basically break the plane up and kill most of those on board.

But if speed is the issue then why cannot a passenger craft just have a large parachute at the back that is deployed when the plane is say thirty to fifty feet or so above the sea surface so that the speed is drastically reduced (at a carefully pre-calculated rate that is safe for all on board, who would in any case be fully prepared for the landing), at which point the plane would essentially just guide gently into the sea at a speed maybe equivalent to that of a fast speedboat?  To be clear I am talking about a parachute that is just intended to add drag and slow the plane down.

Would this work in practice, and if so why don't planes have such a parachute as standard?


texts: Where can I get IFR charts for throughout the world?

texts:
(Note this question asks about VFR charts.)

In the U.S, I can get IFR navigation charts from Aeronav or Jeppesen.

Do IFR charts exist worldwide? If so, where can I go for charts of other countries? (A list would be nice since there probably isn't one canonical source?). If not, what are the alternatives?


texts: Why is the first turbine in a turboprop (or turboshaft) connected to the compressor?

texts:
Typically the first turbine after the combustion chamber drives the compressor as shown in this picture.

(wikimedia.org)

This first turbine spins the fastest and harvests the most energy from the gas flow. This seems inefficient when you want to maximize power output from the power turbine. So why not have the power turbine the first to take advantage of the gas flow and then the compressor/gas producer turbine second?


texts: What should you do when ATC gives you a number to call to discuss a violation?

texts:
Generally speaking, for those that either have experience calling the number, or, preferably, for those that were paid to answer the phone, what are the benefits or pitfalls of calling?

I had a friend that climbed above his assigned altitude once and was given the number, and he called and had an exceptionally friendly chat, and that was that.

Are there any scenarios, such as gross violations, where it might be better to seek legal counsel first before calling, or not calling at all--especially if there is a discrepancy between airman and controller?


texts: How is the weight of an airplane measured?

texts:
Many very large airplanes have specific information of their empty weight. For instance the weight of an empty, regular 747-400 is 393,263 lb (178,756 kg) according to Wikipedia. The Concorde is 78,700 kg.

How is the weight of these airplanes measured so precisely (note that in the 747-400 example is precise to the unit's place!). Is the sum of the weights of all the parts used? Also, is Zero Fuel Weight (ZFW) the same as empty weight?


texts: How did this flydubai 737NG get Max winglets?

texts: I’ve seen this one on my way to the office in DXB. It’s clearly equipped with paired MAX winglets, however the engines are not curly. So judging by symptoms it’s not MAX. Was filming from a car, hence tail number is not visible. It’s A6-FEC, which, according to planespotters.net, is 737ng and 7+ years old. How did it get those winglets?


texts: Are planes assigned different climb angles from the airport by the tower?

texts:
Clearly the angle at which planes take off and climb depends on lots of things (mountains, residential area, aircraft type, wind) but when watching planes take off after another from the same runway, I have the impression that similar aircraft climb at different angles right after another.

So I'm wondering it this is a measure to increase the distance between two planes quickly after they leave the airport? Such that every other aircraft is asked to leave flat'ish (within what the plane and regulations allow) and others more steeply?

The question occurred to me at GVA (single commercial runway).

This is about the initial climb angle, not their course heading.


texts: How much does weight really affect the operation cost?

texts:
Hi given an information from a reliable new source article (https://www.nytimes.com/2008/06/11/business/worldbusiness/11iht-air.1.13628276.html), it was mentioned that "Every 25 pounds we remove, we save $440,000 a year,". I wonder the validity of the statement because it goes against basic math.

Here is what I got,

\$440,000/yr/25 lbs = $17,600/yr/lb

Let's say a passenger weight at 200 lbs, this means by removing one passenger out of the plane, an airline would save   $\dfrac{\$3.5 million}{year \ person}$.

That means that one passenger should be paying more than that amount over the year, but if we think calculate that by using a ticket from L.A. to New York as an example, that's not the case (calculation shown below).

$ \dfrac{\$262}{person}$ $\times$  $\times$ $ \dfrac{4 flights}{day}$ $\times$ $ \dfrac{365 days}{year}$ =
$\dfrac{\$380k}{year \ person}$

I know there must be something wrong in this simplistic calculation, but I couldn't figure out. I am hoping someone here could point that out (with a reference would be awesome).

Thanks in advance.


texts: Do turbine engines on multi-engine aircraft rotate in opposite directions to offset torque?

texts:
I'm not an aviator, I guess I'd call myself an enthusiast. I'm also a physics nut. I've always wondered about this but I equally worried my question posed to a commercial airline crew would land me in the Homeland Security Suites.

On helicopters, torque along the vertical axis is countered by a smaller tail rotor (or a twin main rotor rotating in the opposite direction).

My question is whether the turbines/fans of multi-engine jet aircraft rotate in the same direction. I.e., do both the port engine and the starboard engine rotate uniformly clockwise or counterclockwise?

It seems like if that were the case then maintenance might be easier but it would create some instability along the longitudinal axis of the airframe due to torque and moment arms.

Follow up: I guess, then, that single engine propeller aircraft utilize trim presets to compensate for the longitudinal torque generated by their propeller–correct?


texts: Why do IFR reporting points have odd names?

texts:
I was checking out some flights on FlightAware and went onto the "Route" page for a flight and I saw these IFR Reporting Points with really odd names. Is there a regulatory reason why they have such names?

Page I snipped image from


texts:
I came across the following picture on a news site, in a series of 'this day in...' type items.

The accompanying text reads (in Dutch)

  22 juni 1975 - In Geldrop werd de Internationale Holland Ballonwedstrijd gehouden. Deelnemers uit zeven landen streden daar om de Trophee du ballon libre.

Which translates to

  22 June 1975 - The International Holland Balloon competition was held in Geldrop. Contestants from seven countries competed for the Trophee du ballon libre.

To my surprise, the balloons are round and are closed at the bottom. What type of balloons are these? They don't seem to be hot air balloons, are they?


texts: What is the buzzing noise generated by the engines in this 777 takeoff video?

texts: I've flown a few times in my life, both in economy and executive class. Every time I fly in executive, during takeoff, there is a different noise from the engines. In economy class (behind the engines) the wind sound dominates, but in the executive class you hear the noise in the video below until you're high in the skies. Why is that?


texts: Can a private pilot refuel his small private airplane internationally without passing through immigration or customs?

texts:
I've been a private pilot for many years, but I have never flown internationally in small private aircraft. I'm about to buy a tiny, high-tech, super-efficient 2-seat airplane that has extended range fuel tanks that make it possible to fly 8000km == 5000 miles without refueling (24+ hours).  The longest flights necessary to cross the south-pacific in hops is 4000km (about 16 hours of flight at 250kph).

Such long range makes it possible for this tiny aircraft to fly anywhere on earth.  Nonetheless, I'd have to be nuts not to stop more often than every 16 hours when that is possible: for a meal, potty stop, walk around and stretch body & legs... and eventually sleep!

This raises the asked question.  Can a pilot, with or without one passenger, stop in other nations JUST to refuel without needing to go through immigration (and get a visa for that nation)... just to land, pull up to the gasoline pumps, fill them up, get back into the airplane, then fly away?

Note that this is NOT a question about flying in a commercial airplane on a conventional scheduled airplane flight. I also presume the stop will not involve going inside any building or leaving the refueling area within the private aircraft portion of the airport. It will involve getting out of the airplane, because refueling of diverse small private airplanes is generally done by hand by pilots, not by the huge trucks that fuel jet airplanes. Typically small airplanes just pull up to a pump much like you'd see at any gasoline station, insert credit card, pump fuel into the wings, then fly away.

When I get the airplane, after a month or two of getting used to it in north america, I plan to flying down to Chile with 1, 2, 3, 4, 5 stops between (depending on these rules), then fly to dozens of islands in the south pacific (and land many places and islands that have airstrips, but no buildings (or at least no legal/government buildings).

In the later cases (south-pacific islands with tiny populations), I suspect nobody bothers or cares, because they assume all air traffic is strictly local. But flying down through (or 20 miles offshore) of Mexico through central America then Columbia, Ecuador, Peru and then finally into northern Chile (where I intend to spend a great deal of time) may be another matter entirely.


texts: Why is the A380’s with-reversers stopping distance the same as its no-reversers stopping distance?

texts:
Thrust reversers, found on almost all jetliners1 and on the larger propliners, redirect engine thrust forwards, helping to slow the aircraft in the event of a landing or rejected takeoff.2  This takes some of the load off the aircraft’s wheelbrakes, reducing brakepad wear and tyre overheating, and considerably increases the total braking force available, allowing the aircraft to stop in a shorter distance than it otherwise would...3
...unless, that is, your aircraft is an A380, in which case, your reversers (all two of them), although they do reduce brake wear, apparently do not decrease the aircraft’s stopping distance (my emphasis):

The two reversers do help slow the A380—but not by much. In fact, unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.

How is this possible?  Any increase in available braking force should shorten the aircraft’s stopping distance (even if only by a small amount), so, assuming that the A380’s reversers produce a nonzero amount of braking force, the stopping distance for a given A380 at a given weight on a given runway under given conditions using maximum wheelbraking, maximum aerobraking, and maximum reverse should still be less than the stopping distance for said A380 at said weight on said runway under said conditions using maximum wheelbraking and maximum aerobraking, but no reverse thrust.
Yet, apparently, it isn’t.
Would someone like to explain this?

1: The main exceptions being the Fokker F28 and BAe 146, as well as early Caravelles.
2: A few jetliners, such as the DC-8, Il-62, and Concorde, can also use reverse thrust in flight, to steepen the aircraft’s descent angle without increasing its speed; in essence, the reversers are used as blown airbrakes.
3: This is especially important when wheelbrake effectiveness is degraded, due to, for instance, landing on a contaminated runway4 (which severely limits the amount of force that can be applied to the wheelbrakes without them locking up), with inoperative spoilers (which severely decreases the amount of weight carried by the wheels, and, thus, the amount by which their brakes can slow the aircraft), with one or more blown tyres (which renders the brakes on those wheel(s) useless for slowing the aircraft), overweight (which forces the aircraft to land at a much higher speed, where the coefficient of friction between the tyres and the runway is much lower than at lower speeds), with inoperative flaps and/or slats (ditto), with accreted ice and/or wing-leading-edge damage (ditto numero dos), with inoperative antiskid (which requires that the pilot(s) brake manually, and severely limit the amount of braking force [especially at high speeds] to prevent the wheels from locking up), with one or more inoperative wheelbrakes (for obvious reasons), numerous other things that I haven’t thought of, or any combination of the above.
4: For instance, one that is flooded (hopefully with water, not Jet A-1) or covered in (usually water) ice.