texts: What do I need to know to design contra rotating propellers for a powered paraglider?

texts:
I wonder if anyone has any technical information that would assist in using the correct Size & Pitch Contra rotating Propellers (CRP) on this Foot launched Powered Paraglider engine ?

We are using CRP to Eliminate the dangers of Torque Twist associated when using a single propeller.

I am looking to use standard 100~125cm (40~49") Propellers that have approx. 28~22 pitch.  Noting the Forward prop would need to be a Puzzle type prop, or we would have to increase the forward Hub size, so that it would slip over the Aft prop hub, thus adding more weight & complexities.

This pre-production engine maximum operating speed is planed not to exceed  3'500rpm, so if the Prop output shafts are geared 1:1 with the piston speed or less, the props will also be rotating at 3'500rpm or less.

This is the current CAD design work, the 4stroke, 150cc engine, current weigh approx. 12kg, so it is a very small engine.

So, I hope someone can understand the unique workings of this engine design and move past that and recommend best size & pitch of after-market propellers that would Fit these hubs, preferably also with bolt pattern measurements ?


texts: Why does my Cherokee PA28-180 Lycoming motor run hot?

texts:
Regarding my Cherokee PA28-180. Could you please explain me why my new Lycoming engine with 800 hrs runs hot?

My mechanic says that the EGT #2 should be around 1350 degrees. The minute you lean the fuel at cruise alt, you have to richen it back up to stay < 1350 degrees.
During 1800 rpm run-up & during cruise speed of 135 mph, the oil pressure is just barely under the red line & it stays there for the duration of the flight. My mechanic says that's ok for this motor.
My mechanic says that we are to stay away from the 2100 rpm to 2400 rpm range. That's red line for our motor. Why?


texts: Are aircraft being fitted with brighter anti-collision lights?

texts: I live and work near to DFW airport. Yesterday, I noticed an inbound jet with obviously brighter strobes (anti-collision lights) than any other jet I've seen before. (I believe this was an American Airlines Jet with an engine under each wing.) Does anyone know if aircraft are being fitted with brighter anti-collision lights? This particular aircraft was really noticeable against the low overcast clouds.


texts: Why have helicopter top speeds not increased much over time?

texts: With advancements in technology why there isn't much increment in helicopter top speeds from what they were in the 1980s? We have newer designs like the Eurocopter X3 which is a hybrid, but the speed is still limited to 300+mph.


texts: Chocks - why the wide variances in price?

texts:
In a comment to a question about setting the parking brake, @rbp said to just get a set of wheel chocks and use those instead. I was piqued - it never occurred to me you'd need your own, I thought they'd be littered around the tarmac for common use - and did a quick Google Shopping search for "aircraft chocks". I was surprised to see a wide price variance, even within a subset of relatively small-size chocks.

For instance, here is a pair of 10" rubber chocks with 3ft rope, about 15 lbs, for \$15. Here is what looks like exactly the same thing, for \$98. Tigerchocks make considerably lighter ones, but they are \$120-ish per chock (over \$200 for any roped pair) while other lightweight designs are as cheap as \$30 for about the same size. Other designs seem to vary between $20-60 for a roped pair, and have noticeable differences in size and design, but c'mon, they're a wedge you put under the tire to stop the plane rolling.

How much of this variance is "you get what you pay for" (more money equals a better product in some way; lighter, grippier, more durable etc) and how much of this is "caveat emptor" (the aviation crowd are used to paying a lot for their gear, so some yahoo with an MBA says "let's see how much we can milk them for a pair of rubber blocks tied with a rope")?


texts: Could a kerosene fueled jet engine run on methanol without significant modifications?

texts:
Could a kerosene fueled jet engine run on methanol without sacrificing performance other than specific impulse? Would it require changes to the fuel injection/turbopump system? Would the combustor require a redesign? Consider both turbo engines and ramjets
(this question was previously posted on space SE due to a mixup, I've deleted it now)


texts:
I was on a flight from Philadelphia (KPHL) to Boston (KBOS), after some delay and some change of route due to weather, the captain announced that we will be cruising at 7000' due to delays in the area.

The history of the flight is here: https://flightaware.com/live/flight/AAL2606/history/20190618/2235Z/KPHL/KBOS

My question is two fold:

Why cruise so low with such an aircraft (A319)?
What is the impact on fuel consumption, knowing that we were also slower?


texts: Downwash distribution on basis of Lift distribution

texts:
I am new here so I might make some elementary mistakes. Correct me if I am wrong.
I just stumbled upon the downwash distribution for a given lift per unit span distribution along the wingspan. I have attached a photo for your reference.

I was wondering that if we look upon a $dy$, an infinitely small spanwise slice of the wing, then the lift it produces should be proportional to the downwash it created as more downwash equals more distortion which equals more lift. But we can clearly see that at the end where the lift is minimum the downwash is maximum and at the center where the lift is maximum downwash is minimum. Could anyone please explain it?


texts: What is the FMS Bridge Visual 28R approach at SFO?

texts: I've read that SFO has a specialized FMS Bridge Visual approach to 28R that is not published but instead is custom tailored for specific operators. What exactly is this approach and how does it work? When is it assigned, and what advantage does it have over other visual approaches to runway 28R?


texts: How could a 45 years old DC10 be still in service with one of the largest cargo airline?

texts:
It is amazing to see this 45-year-old DC10 freighter still operating for FedEx regularly:

I know the lifespan of an aircraft is not rated by ages but flight cycles, but an actively used DC10 over 45 years must have exceeded the designed flight cycle right?  However, I regularly come across 30+ or even 40+ years old aircrafts on FR24 that are still in service, mostly freighter though. Wouldn't they raise any safety concerns? Besides, how could airlines operate them efficiently?


texts: What happens with RNAV procedures on the way from AIP publication to FMS database?

texts:
I'm particularly interested in Approach procedures, but I guess it applies for RNAV procedures in general.

On one side, the national Air Navigation Service Provider (ANSP) is responsible for the design of the procedure. The procedure charts are usually available as PDF files through AIP website (e.g. the terminal procedures available at FAA).

On the other side, the RNAV procedure is coded in binary format inside aircraft's FMS. The airborne databases that can be directly loaded to the FMS are provided by external companies (Jeppesen, Lufthansa, Navigraph).

What happens between those two points is kind of puzzling for me.

I know of ARINC-424 standard for aircraft navigation data that is used for "preparation and transmission of data". Then there is AIRAC cycle which as I understand provides fixed dates for any changes to become effective.

The questions are:

Who takes responsibility that the database being sold to airline or any user reflects the original procedure published by ANSP?
How does the coding process look like. Is it based on PDF charts or there is another exchange format available (e.g. AIXM)?


texts:
On a commercial aircraft, the number of engine is usually 2, 4 or 6. When the technician or LAE was given task to inspect an aircraft engine no 2 on a 4 engine aircraft. Which engine would they go to?

2 different lecturers of mine had 2 different answer for this and both have experience in working with aircraft engine.

Lecturer A said:

Lecturer B said:

Which one is right? Requesting help from Technician or LAE. A brief explanation would be really helpful too.


texts: How to calculate the required motor power and rotor size with respect to the weight of quadcopter?

texts:
I want to build a quadcopter but don't have any idea about motor and rotor size selection.
Is there a formula or equation to use? What are other things that need to be considered? Trial and error method would be waste of time and money.


texts:
Why is the horizontal stabilizer of the Lazair swept back?

I understand the hinged elevators are perpendicular to the fuselage, but the horizontal stabilizer is actually swept back.


texts: Does the mixture and throttle setting affect the quality of priming of fuel prior to start?

texts:
This question is a generality.  For airplanes with small reciprocating engines, does the mixture and throttle setting at the time of priming affect the quality of the priming or the engine start, or is the priming unaffected by mixture and throttle positions?

Does it make a difference if the engine has carburetor or fuel-injected in regards to mixture and throttle at priming time?


texts: How much does the swirl of engine exhaust affect aircraft performance?

texts:
Most multi-engine aircraft have engines that rotate the same direction on both sides of the fuselage (e.g. the GEnx rotates clockwise, as viewed from the front, there is no 'mirrored' version).

What would the effect (drag, stability, turning performance) be, if an aircraft were to have oppositely-turning engines on each side of the aircraft (especially if the engines were rotating counter to the wingtip vortices)?

Note that propeller and jet engines may have significantly different answers!


texts:
I was in a car dealership waiting room and saw this video of an airport that was slowly scrolling down the screen (like River Raid).

The video is in motion - the cars on the street are moving and the 2 planes on the left were taxiing. The scrolling is very smooth - as if it's a satellite or maybe blimp.

Is this real video or just CGI? What airport is it?

How did they get the video while it was obviously in use? Wouldn't the airspace above the airport be restricted?


texts: What is minimum information required to identify if two people will be on the same flight?

texts:
I asked this question on travel.stackexchange and got an amazing response but I was advised it better suits aviation.stackexchange and should ask here for a better response, so here it is.

I have a set of users and their itinerary details. I want to figure out who all will be sharing a common flight. I do not want to rely too much on the "Departure time" as people could have entered an approximate time into the system. How can I figure this out with minimal information?

Initially, I thought two people with the same flight number and same departure date would be on the same flight. But the same flight can be used again on the same day. Would the combination of "Flight no + departure date + departure city" be enough to identify a unique flight itinerary?

What would be optimal information to identify this?

I also have to keep in mind that there could be people with multiple flights in their itinerary and if at least one flight is common with another passenger, that has to be shown too.


texts:
I know that each transponder is linked to a unique 24-bit code assigned by ICAO. But to be seen by the Secondary surveillance radar the pilot set the squawk code (4 digit octal code) on the transponder as dictated by the Air Traffic Controller (ATC).

So, why do I need a ICAO 24-bit code? Has it any utility during navigation, or just during maintenance to identify the single transponder (and the aircraft associated)?


texts: Why doesn't extending the flaps on a B-2 send it into an uncontrollable dive?

texts:
The Northrop-Grumman B-2, a tailless-flying-delta-wing aircraft, has a set of flaps along its trailing edge, as seen (for instance) in this cutaway diagram:

(Image from Funker530.)

But tailless delta-winged aircraft (except for those few equipped with canards) can't generally use flaps, because a tailless canardless delta-winged aircraft has no way of countering the nosedown pitching moment produced by extended flaps.

How does the B-2 avoid pitching down uncontrollably when its flaps are extended?


texts: How does a jet engine handle suddenly entering a lot of rain?

texts:
From my related question, it seems that an engine suddenly shut off would suffer from dangerous differential cooling from the airflow. This differential cooling would cause the engine to warp.

So now I'm wondering about a jet engine that suddenly enters rain. Wouldn't this initially cause severe differential cooling and thus warping, maybe even cracking? (P.S. would the same thing happen from entering a thick, dark cloud?)

How does the engine handle a huge amount of sudden rain ingestion? To me it seems like the sudden cooling on one side of the engine would cause thermal contraction, causing all sorts of problems.

EDIT: There seems to be a lot of comments about rain certification for engines and the fact that jets fly through rain all the time with no problem. I'm not questioning any of that. What I want to know is, how a jet engine handles the differential cooling caused by rain without warping or cracking?


texts: What type of computers are in a flight system?

texts:
I know there are many types of flight computer systems, with varying names and capabilities.

I'm more interested in knowing what the computers, themselves, are made of?

They certainly are not "off the shelf" computer components - and are more likely specifically built single-board computer systems running some sort of Real-Time OS. Where can I find out more information about one (and/or purchase one) if I were inclined to test software on one at home?


texts:
Which airlines can be designated as "major"? what difference between them and other airlines?
What qualities airline should have to be "major"?
I can't find any proper description, but I heard about it a lot from aviation news.


texts: What is the benefit or motivation for having Class G airspace?

texts:
I'm looking at the differences between Class E and Class G (AIM 3-2-6) airspace in the United States and I get that there are different flight condition requirements depending on AGL/MSL altitudes, but if you're outside a Mode C veil and around an untowered airport (So you don't need a transponder, don't need a radio), why not make everything Class E?

I think the answer came to me while writing this out...is it this simple?

Does Class G exist because for whatever reason (Radar services not available, technical reasons, etc.) ATC is unable to provide IFR separation services in that area, so it has to be deemed "uncontrolled?"

Is there some other reason why Class G exists besides being a catch-all?

  Class G airspace (uncontrolled) is that portion of
  airspace that has not been designated as Class A,
  Class B, Class C, Class D, or Class E airspace.

Like is there some benefit that you get when you're in Class G instead of Class E? The only thing I could think of is that the flight visibility is less than 3 miles but more than 1, it's daytime and the cloud deck is lower than 500 feet AGL (since you just need to be clear of clouds and 1 SM visibility), you could take off VFR in Class G and you couldn't take off in Class E. (However, you'd still have to be sure not to be engaged in Careless or reckless operation (14 CFR § 91.13).)


texts: What is the difference between an RNAV and a GPS approach?

texts:
How does the FAA decide to name an approach an "RNAV" approach or a "GPS" approach?
Is it because for RNAV approaches, there is the option to use something besides GPS like an inertial navigation system based on ground NAVAIDs vs GPS which actually requires use of the US maintained and monitored GNSS GPS system?


texts: How practical is laser designation against helicopters?

texts:
Laser designation is a fairly common method for guiding missiles and precision bombs, but how does it perform against aerial targets?

Given the ranges and kinematics involved, this method could be too challenging. I know the effectiveness is also dependent on atmospheric conditions, but what are the other limiting factors?


texts: Why are military and civil aircraft landing gear generally so different?

texts:
Why do military aircraft have a lower landing gear than civilian? I have in mind the difference between a Lockheed C-130 Hercules and a Boeing or Airbus.

The first possibility that jumps to mind is that one is more comfortable than the other, which is more robust. But would an aircraft designer reduce robustness to provide more comfort?


texts: Why are parking brakes not used for parking jetliners?

texts:
From the question 'Do I Set the Parking Brake On the Ramp?' it is concluded that you do not set the parking brake when parking the aircraft.

The question concerns small aircraft which can be parked for a longer period of time. However, commercial jets (jetliners) are also parked at the gate without the parking brake engaged and rely on blocks/chocks placed around the wheels.

Then why is it called the "parking brake" as it is not used while parking the aircraft? Other wheeled vehicles like cars, trucks and buses are always parked on the parking brake.


texts: Why was the U-2 so different from the SR-71?

texts:
Both were designed for the same goals: taking photographs at high altitude, avoiding radar. Both were designed by the same company with a few years apart. Yet one is a "jet glider", with large wingspan, small chord, subsonic, and the other is a ultra high speed, delta wing airplane.

Why did these two planes took such different approaches to perform similar tasks? What would be the pros/cons of each? The SR-71 was developed later, so it could be seen as a better approach, yet it was retired, while the U-2 is still in use.


texts: What is the difference between a nautical mile and a statute mile? And what is a knot?

texts:
What is the difference between a "nautical mile" and a "statute mile?"

And what is a "knot?"


texts: What is the total lift equation of a helicopter with 3 Flettner rotors?

texts:
I'm doing research regarding the possiblity of using Flettner rotors on helicopters.

I would like to derive the total lift equation for a helicopter that consist of 3 Flettner rotors.

Given that:

The general lift equation is

$$ F = \frac{1}{2} \rho V^2 S_{ref} C_L $$

where F is the lift force.

The Kutta-Joukowski Lift equation is

$$ \frac{F}{L} = \rho V G $$

where F is the lift force and L is the length of the tube.

Is the total lift equation equal to?

$$ F = \frac{1}{2} \rho V^2 S_{ref} C_L + 3\left(L \rho V G\right) $$


texts:
(Wikipedia) A Boeing 737 main landing gear arrangement.

What defines a landing gear bogie (truck)?

In its airframe maintenance handbook, the FAA defines it as:

  When more than two wheels are attached to a landing gear strut, the attaching mechanism is known as a bogie.

But, they go on and describe the Boeing 777 main landing gear (MLG) as:

  A triple bogie main landing gear assembly.

That means each lateral pair of wheels is a bogie, which is what the undercarriage arrangements Wikipedia article calls a 2-wheel nose landing gear.

For me, a bogie is when a strut holds a longitudinal arrangement of wheels (like trains). For example, the MLG of a Sukhoi Su-34 (shown below) would be a bogie, but not a Boeing 737 MLG, despite both having two-wheels each.

Are there technical terms to distinguish the two images shown in this post?

(Wikimedia Commons)


texts: Is there a minimum number of people needed for an aircraft pushback?

texts: This seems a bit wasteful. Is there a legal requirement for a minimum number of people and if so, on what basis does this vary? (airline, airport, aircraft type, etc)


texts: An example of remotely controlled flight control surface?

texts:
I'm aware of hydraulic, mechanical, and electrical ways to control flight control surfaces on an aircraft, but are there any examples of control surfaces which are remotely controlled? Can you explain their working?
Also, will this system come under Remote Position Control (servomechanism), or is it something different?


texts: What happens when you call 866-GA-SECURE in the US?

texts:
I live in the US, near a fairly dangerous road, and I've called 911 a few times to report car accidents outside my home.  It's a lot like giving a PIREP - you give the necessary information and the appropriate help is dispatched.  All very simple and clean.

I've never heard of anyone calling 866-GA-SECURE.

What happens when you do?  Who do you talk to?  Who responds?  How fast is the response?  What can you expect?


texts: What does the "DO NOT USE FOR NAVIGATION" indication mean?

texts:
Sometimes when I'm browsing IAC charts online I find a "DO NOT USE FOR NAVIGATION" notice printed on the chart. Not always though.

For example, have a look at the chart for Queenstown RNAV (RNP) Y RWY 05.
See the notice there?

I have always wondered why do procedure designers put these notices on their charts. I find it almost contradictory, since I think these charts are the best source of information that an aircrew can have to navigate/maneuver. Isn't it ironic?

I'm sure I must be missing something.

Can anybody shed some light on this?

PS: These are not SIM charts. These are real charts from the AIP.


texts: What does it mean to fly a procedure turn?

texts:
So, I'm flying IFR to Newport (KONP) for the ILS RWY 16. There's an aircraft on the approach, so I'm cleared direct BUHRS at 5000' to enter the hold as published.

I get to BUHRS, I turn outbound on the hold, and am "cleared for the approach". (Note: Not "straight-in").

So, what is my next step?

AIM 5-4-9 says I'm required to fly the procedure turn, but I can't find a definition of what that actually means (i.e. do I have to overfly the waypoint to "start" the procedure turn, or does it just mean remain in the protected area?). The options seem to be:

1) Turn back to BUHRS, overfly BUHRS, turn right (ending up exactly back where I am right now), intercept the localizer outbound, descend to 2600.

2) Intercept the localizer outbound, descend to 2600.

If #2 is correct, then there's an additional point of consideration. 5-4-9a1 says I have complete discretion in how I fly my procedure turn. Certainly turning immediately inbound fits within that discretion (instead of turn right, intercept outbound, turn left, turn left, turn right, intercept inbound). Or, what about continuing to fly outbound by heading for a minute then turn inbound and intercept the localizer?

A simplistic reading of the AIM seems to indicate #1 is correct. I asked AOPA, they say #2 is correct.

Is #2 correct? If it is, wouldn't an immediate turn inbound also be correct? What is the definition of "procedure turn"? Does it require flying over a fix to "start"? Or can you be anywhere in the protected area?

The easy solution is to ask for a straight-in clearance, but assume you're not in radio contact or your request is denied.


texts: Why is the drogue parachute jettisoned on the runway?

texts: Why is the drogue parachute of a military plane jettisoned on the runway? Why not drag it to the parking area for safe removal, inspection, and repacking?


texts: What happens if I activate VFR flight plan later than filed ETD?

texts:
Let's say I filed a VFR flight plan with ETD (1500), en route (2 hours), ETA (1700)

If I depart and activate the plan at 1600, now the new ETA will be 1800 which is an hour later the the filed ETA. Is the ETA changed automatically on the system? or do I have to contact FSS and change to prevent initiation of the search and rescue?


texts: What is the reason for the strips on the nose of the Embraer E175

texts:
Recently I boarded a KLM flight with an Embraer E175, when I noticed the strips on the nose

(see image, marked with the black circle).

Own image

This Embraer E190 also has it:

Image source

Whereas this A320 does not have it, is it an Embraer specific feature? What is it for?

Image source


texts: Did the space shuttle have a stall warning system (such as a stick shaker)?

texts:
I've been wondering about this, but I can't find any sources one way or the other:

Was the space shuttle equipped with a stick shaker and\or other stall warning system?


texts: What is the longest period of time an aircraft type has been grounded due to safety concerns?

texts: Obviously inspired by the current 737 Max situation, what is the longest period of time that any individual type of airliner has been grounded for safety concerns (excluding those that never returned to service)?


texts: What are the general problems faced for maintenance in fuel inerting systems?

texts:
Currently most of the nitrogen generation systems have Air Seperation Modules (ASM) and other associated mechanical components to generate Nitrogen Enriched Air.

Hence, are there any inherent problems with the system in terms of maintenance, weight or the controller?


texts: What is the meaning and difference between CTAF, UNICOM and MULTICOM in the US? Could you please give examples of radio communications with the correct phraseology to be adopted in each case?


texts: Are there benefits in training instrument students how to fly a DME arc?

texts: With more instrument approach procedures being designed for RNAV/GPS equipped aircraft, and considering the high level of radar coverage currently available, is there a need to spend much valuable training time teaching students the skills and techniques for flying an approach using a DME arc?


texts: How do propeller planes suddenly make noise?

texts:
I was wondering: how can a propeller plane, single engine or otherwise, be flying along relatively silently and then start making noise, often very loud--and then turn it off just as quickly? Are they descending/ascending? It seems like the engine must be straining.
Thank you.


texts: For how long after the last A380 delivery does Airbus have to provide spare parts for it?

texts: After Airbus's announcement that they plan to discontinue A380 production in 2021 after the last orders are filled, how long will they have to guarantee the availability of A380 spare parts?


texts: Why do VFR-flights need a clearance in class D airspace?

texts:
I ask myself why VFR-traffic has to get ATC-clearances in class D airspace, because as far as I know, ATC doesn’t provide separation for VFR-traffic in this airspace class...
So why for example is a VFR pilot given the clearance (or is that an instruction) to maintain 4000 ft in class D airspace, if he is responsible for the separation, and not the controller?


texts: What is the go-around pattern and procedure for Heathrow?

texts:
An hypothetical situation in which an airplane taking-off at Heathrow must go-around / land immediately after taking-off. What will happen during this scenario:

Is there any specific action to be done in this scenario, i.e. setting transponder to some code?

What is the go-around / return pattern for Heathrow? Over which villages will the plane fly and at which altitude?


texts: What are the evenly-spaced "bumps" on Bell X-1 tailplane?

texts:
The tailplane of the Bell X-1 had four evenly-spaced "bumps" on each side--what was their purpose?  (Screen shot from The Right Stuff.)

Another image

If they're hinges for the elevators, then how come the rudder and ailerons have flush hinges?


texts: How prevalent are anti-explosion bladders in fuel tanks?

texts: Some aircraft fuel tanks are fitted or retro-fitted with internal bladders, to prevent fuel evaporating inside the tank. I've heard of this being a requirement for at least one type, perhaps because of a poor fuel tank design, but how commonplace is it? How many aircraft have these bladders?


texts: Is there any legitimate reason for adding momentary power when descending at idle with full carburettor heat on?

texts:
Scenario: While demonstrating a simulated engine failure emergency landing a flight instructor puts on carburettor heat and reduces the throttle to idle of a small single engine Cessna. After a couple of minutes descending to the simulated emergency landing site, the CFI adds throttle "to clear the plugs" for a few seconds, then brings it back down to idle to complete the demonstration.

Is this is a legitimate thing that needs to be done for safety?

I've seen several pilots do this, and to me it always seems like cheating, because they are coming in a little short of their landing target.

How much plug fouling can occur in 2 or 3 minutes of idle with carburettor heat at low altitude?
How much good can 3 to 4 seconds of full power do?
Is there something else about this that I'm missing? (I couldn't find anything on this after a brief Google search).


texts: Do all airports have the authority to impound aircraft for overdue fees?

texts:
In the 'Collapse' section of the Thomas Cook Wiki, it states that

  At around midnight on 23 September, airports in the UK began to impound Thomas Cook aircraft upon arrival, citing "default in payment of airport charges"

Do all airports have authority to do this? If I refuse to pay a $15 landing fee in a Cessna, can they impound the aircraft?


texts: Do negligible weights affect the control of a commercial aircraft?

texts:
I was watching a video and it said that switching seats on a commercial airplane would be fatal. "Switching of seats from the rear of the airplane to the front seats would result in probable accident". I think if a person weighing between 40-110kgs would be considered as of negligible weight relatively to the aircraft weight.
Do such acts by passengers really affect the controls?

Reference:


texts: Do some radial engine planes have a two-speed starter motor?

texts:
(YouTube)

Watching the Connie fire up her engines I wondered, do some radial engine planes have a two-speed starter motor to replace the ground crew "pulling the props through"?

In other words, low-speed–mags-off to test for a potential hydraulic lock.

I do realize the props could have been pulled through off-camera before being towed out for the show.


texts: Why do emergency exits over the wings have "step up and through motion" rather than having floor level exits?

texts:
My questions stems from the following paragraph from Wikipedia:

  Additionally, during aircraft evacuations, it has been found that the
  majority of overwing window exit designs of Boeing 737 (NG) Next
  Generation Line along with the Airbus A320, hamper evacuation in
  comparison with traditional floor level exits due to the inherent
  "step up and through motion" required of passengers as they exit the
  aircraft, unlike the designs of older generation wide body aircraft
  such as the McDonnell Douglas DC-10 and Lockheed L1011 which are all
  floor level.

One more question I had, wouldn't it be better to have the same emergency exit procedures with respect to opening the exit door etc. on all type of commercial aircrafts?


texts: What is the Extent of the Emergency Authority of the Pilot-in-Command (FAA)?

texts:
When writing an answer to this question regarding flight deck access during flight, I mentioned the authority of the PIC to deviate from regs as necessary for safety purposes, citing the usual FAR, 14 CFR 91.3(b), which says:

  In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.

However, the exact wording used here made me wonder exactly how far this reg has been interpreted to go. In particular, it grants the PIC emergency ability to deviate from "Any rule of this part", which would be 14 CFR Part 91. So, does this authority extend only to Part 91 of the FARs or does it extend to all of the FARs? The exact wording seems to suggest it only applies to Part 91 and not, say, Part 121, which was the part under consideration in the other question.

So, the major things I'm wondering are:

What is the extent of the authority granted by 14 CFR 91.3(b)? and
If 14 CFR 91.3(b) indeed only applies to Part 91, is there a similar explicit emergency PIC authority exception to the other Parts of the FARs?

Obviously, the PIC is the one in charge and will deviate where necessary for safety regardless of regs and worry about the explaining later after he's ensured he'll be alive to explain, but I'm curious about the regulatory basis for deviation from FARs.


texts: Can you fly direct to your destination if you can cruise above FL450 regardless of airways?

texts: To my knowledge, the high altitude enroute charts only apply to the altitudes between FL180 and FL450. Does that mean you can plan direct to your destination if your cruising altitudes stay above FL450?


texts: What is the difference between a trim tab and a servo tab?

texts: They both seem very similar but can someone please explain their main differences and principle of operation?


texts: How are military aircraft type certificated?

texts:
It seems that FAA requirements for any particular aircraft revolve heavily around the aircraft's type certificate.  Civil aircraft are broken up into several categories based on weight or passenger count, etc.  But I did not see a section on military operations.

Do military aircraft undergo type certification?


texts:
Airplanes with propellers were invented a long time ago. After that, jet engines came into existence. My question is: why do we still have propeller engines?

The reasons I can think of are:

They are cheaper;
They cannot achieve very high speed;
They are not very noisy (though not always).

Besides these, are there any other reasons general aviation airplanes built nowadays don't have jet engines?


texts: Did Boeing or Lockheed ever seriously consider releasing a widebody airliner powered by low-bypass engines?

texts:
During the 1960s race to build the first widebody jetliner, each of the three major engine manufacturers was racing to put out a high-bypass engine for one of those jumbo jets:

Boeing went with Pratt & Whitney’s JT9D for their 747.
Douglas (which soon became McDonnell Douglas) chose General Electric’s CF6 to power the DC-10 (Airbus also chose the CF6 for the A300 when they jumped in a couple of years later).
Lockheed, for the L-1011, put their money on Rolls-Royce’s RB211.

Of the first three widebodies, only the DC-10 (whose power plant was a fairly straightforward conversion of the TF39 used on the C-5A Galaxy, which had been the first high-bypass turbofan ever to enter production) escaped being held up by engine difficulties; the L-1011 was held back for years when the RB211 ran into serious delays which allowed the DC-10 to beat it to market and strangle the TriStar in the schoolyard, 1 nearly bankrupting Lockheed in the process.

What isn’t as well known is that Boeing experienced delays of similar severity with the JT9Ds that were to power the 747; for a long while, there were rows upon rows of 747s sitting on the ramp at Boeing Field, complete but for having concrete blocks hanging from their pylons in place of the engines that could not yet be trusted on a production airliner.  Only Boeing’s massive head start enabled the 747 to beat the DC-10.2

Did Boeing or Lockheed ever seriously consider releasing an interim widebody with low-bypass turbofans (for instance, a 747 with eight JT8Ds mounted two to a pylon in conjoined pods, B-52-style) while they waited (and waited) for the high-bypass engines to become ready?

1: It wouldn’t be accurate to say that it strangled the TriStar in the cradle, given that the L-1011 did, in fact, manage to enter production and sell 250 aircraft.

2: Enabling Boeing to remain solvent in the process, as Boeing, like Lockheed, had bet the farm on their jumbo jet.  Unlike Lockheed, they didn’t lose it; however, if the 747 had been a failure, it would have bankrupted Boeing.


texts: Can I use actual IMC time for the requirements in 61.109(a)(3)?

texts:
I needed extra instrument time for my VFR checkride but it was cloudy for my lesson. My CFII and I turned it into an introduction to IFR lesson and we flew 0.3 actual and 0.3 simulated (with the hood) and did 1 ILS approach in IMC.

61.109(a)(3) says that the following instrument training is required:

  3 hours of flight training in a single-engine airplane on the control and maneuvering of an airplane solely by reference to
  instruments, including straight and level flight, constant airspeed
  climbs and descents, turns to a heading, recovery from unusual flight
  attitudes, radio communications, and the use of navigation
  systems/facilities and radar services appropriate to instrument
  flight;

Is it correct to assume that I can use the IMC time for this?


texts: Why does the Apache create much more rotor noise than the A-129?

texts:
The AH-64 Apache attack helicopter was upgraded several times after its first flight in 1974. The Apache Longbow was a major upgrade which entered service in 2003. On the other hand, Agusta A-129's first flight was in 1983.

I have two questions:

Why does AH-64D have much high rotor noise? Why wasn't there any effort to suppress the noise in the upgraded versions?
Why does A-129 have lower rotor noise (i.e. the chop chop sound is almost absent) even though its tail rotor isn't covered?


texts: Is there an official FAA source for time zone of an airport?

texts:
Looking at this answer, from TypeIA, to the question How to get timezone from airport code (IATA/FAA) .

This person is recommending the NASR database, which is good because it's official FAA stuff, but like other users I'm not able to find any information about time zone for an airport in NASR.

Is this information available via NASR or from any other official FAA source?

I do know that I can derive the information from lat/long etc., but what I'm looking for is the official FAA time zone designation for each airport, if such a thing exists.

EDIT: Sorry, to be clear, I'm looking for a digital version of this data suitable for use in a database or app.


texts: Are these pressure and velocity distributions calculated by CFD simulation correct?

texts:
I am simulating wind tunnel tests for a NACA64210 airfoil with the following conditions:

$P_\infty=101300$ $Pa$ ; $\rho = 1.23$ $kg/m^3$ ; $U_\infty = 29.99$ $m/s$

I performed the simulation with Solidworks Flow Simulation, and I obtained the following plots.

My question is about if these plots make sense and can be correct.

For instance, I am wondering why in the velocity plot, the velocity is not zero at the leading edge (provided it should be a stagnation point), maybe it's because the wind tunnel speed is low.

On the other hand, as far as I know, the pressure distribution in a wing should be smaller in the upper side of the wing than in the lower to successfully create lift, in this case it seems to be equal at both surfaces. Also, there's usually a suction closer to the leading edge that I cannot detect here.

I just need a review of my plots to know if they are correct or not, and if they are not correct what might be the cause of it.

P.S: The only setting that I was not sure about what to input, was that I enabled that the air was laminar and turbulent. I'm not sure if I should have stated only laminar, instead.


texts: Why do we have to do an alternate brake check during preliminary cockpit preparation?

texts:
As part of the preliminary cockpit preparation in my company’s older A320s we have to perform an alternate brake system check but not in the newer ones as per FCOM Normal procedures as below. I found out that there is a system difference but didn’t fully understand could someone please explain the difference?

  ALTERNATE BRAKING SYSTEM
  Note: The purpose of this check is to
  verify, before the first flight of the day, the efficiency of the
  alternate braking system (absence of “spongy pedals”).
  Y ELEC PUMP
  pb-sw....................................................................................................CHECK
  OFF
  CHOCKS..............................................................................................................CHECK
  IN PLACE PARK BRK
  handle.......................................................................................................................OFF
  BRAKE
  PEDALS.....................................................................................................................PRESS
  Apply maximum pressure on both pedals.
  BRAKE PRESSURE (on BRAKE press
  indicator).................................................................CHECK
  Pressure must build up without delay symmetrically on left and right
  sides for the same application simultaneously applied on left and
  right pedals. With full pedal deflection, the pressure must be between
  2 000 and 2 700 PSI.
  BRAKE PEDALS................................................................................................................RELEASE
  PARK BRK
  handle........................................................................................................................ON
  The parking brake must be on during the exterior inspection to allow
  the flight crew to check brake wear indicators.


texts: What are the FAA regulations on lighting for ultralight vehicles?

texts:
I'm in the process of scoping out a project involving an ultralight vehicle and some Neo pixel LEDs.

In the US, there are many regulations for lights on cars. Things like the location on the vehicle, the direction, color and blink rate are all regulated.

What lighting laws apply to ultralight vehicles, as far as location, direction, color and blink rate?


texts:
An airline filed the following flight plan:

  [...] IRK.J96.SLN..LANCY.J134.PKE [...]

The cruise altitude was around 30k feet.

Waypoints in J96 are:

LAX PDZ YCDIL PKE* LANCY* DRK KEYKE GUP CIM GCK SLN* AGENT KIDER IRK* NORIS PIA JOT

J96 spans between 18k-45k feet.

So it means that someone put a direct in the middle of an airway. Why was the flight plan not filed with an all-airway routing like this:

  [...] IRK.J96.LANCY.J134.PKE [...]

Is it common practice to omit some points in an airway?


texts: Are CO2 cartridges not considered explosive?

texts:
I've recently starting riding a push bike to work and got myself a CO2 pump and some cartridges (like this), which I promptly forgot about. As a result, when going on work trips and holidays, I had a cartridge in my bag when going through airline security.

I estimate roughly 15 airports (some duplicates) either didn't detect the cartridge or just ignored it. Perth International is my main airport, but I also visited Singapore 3 times (so bare minimum of 6 security checks there. Is this normal behavior/protocol? I would have thought that while CO2 cartridges are single use, they probably present more danger than other prohibited items, such as nail clippers.


texts: If the cabin temperature controller does not function, does the pilot have to make an emergency landing?

texts: The cabin temperature controller in commercial airlines, controls the cabin temperature. But if for any reason, it does not function, does the pilot have to make an emergency landing, or can he cruise to a lower altitude for normal temperatures?


texts: What is the air temperature inside of a tire right after landing?

texts:
What is the maximum design air temperature inside of a tyre of an Airbus A380's and a Boeing 747-800's main gear fitted with brakes, before landing after a 10 hour flight and right after landing?  Are there instruments to measure this? Do pilots take readings before and after landing?

Are there instruments to warn pilots about tire irregularities prior to landing? If so, what is the procedure then?


texts: How does propellers' pitch change during the use of reverse thrust in turboprop/propfan propelled planes?

texts:
Which way do proplellers turn during the use of reverse thrust in turboprop/propfan propelled planes:

A) Do the leading and trailing edges of propellers remain the same or...

B) Do the propellers turn in the opposite direction, so that the leading and trailing edges of propellers swap?

I tried to show what I mean in the picture:

source: https://es.123rf.com/photo_69655677_cerca-del-motor-de-turboh%C3%A9lice-del-avi%C3%B3n-con-h%C3%A9lice-partes-del-fuselaje-de-un-avi%C3%B3n-alas-y-cola-sobre-fondo-de.html


texts: How to Tell Flight Following You Want to Change Your Destination?

texts: I want to fly the LAX Coastal VFR Transition Route northbound, and I want to do the whole thing with flight following.  When I get near Van Nuys airport, I'll need to tell ATC (flight following) that I want to change my direction and head eastward to a different airport.  How do I do this?  And more broadly, how do I tell flight following radar services that I want to change my destination?  For some routes it seems easier for me to have them follow me with radar services to a certain airport that I don't intend to land at, then ask them to change as I fly to a different airport.


texts: Is it possible to load (and not activate) the approach procedure on a Garmin 1000 or 430?

texts:
I noticed sometimes when I fly with a G1000, or Garmin 430 and am doing multiple practice approaches I can't always load my next approach. It forces allows me to activate the approach, which would sequence me to the IAF of the next approach, and sometimes I may not be cleared to or ready for that.

Why is activate the only option?

How do you get around this?


texts: Are test pilots certified to fly all aircraft types?

texts:
I just saw an hour long MIT lecture for no reason and the lecturer said he has flown over 70 kinds of aircraft.
Does that mean a test pilot is certified to fly almost anything?


texts: What call sign does Marine One use when the President is not on board?

texts: How would the pilot of Marine One identify himself to air traffic control without the President on board? Does it have an N-number? If anyone knows, I would like a specific call sign/N-number of any of the Sea Kings. In particular, how would a Sea King pilot flying alone identify themselves to air traffic control?


texts: Why do I not always hear ATC read back by pilots (on required instructions)?

texts:
I enjoy tracking air traffic at my local KORD.  I listen on LiveATC and use my private virtual radar setup to get "real-time" traffic info.

I understand which instructions need to be read back by the pilots per this question however on more than one occasion I don't hear read back on critical vector info on departure, despite the visual confirmation of instruction (pilot making proper vector and speed adjustments).

I tend to notice this with bigger birds (777,747,340), however smaller regional jets almost always promptly read back.

Questions:

Is there an alternative way of ATC instruction acknowledgement? (Other than read back?)
Is it possible that the reply is somehow on a different frequency?
Is this just a problem with LiveATC? (One theory is that A/C leaves receiver coverage area and that's why I don't hear reply, however on approach side much bigger distances are heard in my area)

Thank you

I did verify that indeed the aircraft that I don't hear read back from receives special departure frequency by tower.

Once tower clears aircraft for take off and hands them off to departure controller they use "departure" frequency to read back instructions.  It is typically different from standard departure frequency.

The only thing that is not clear is if there is any rhyme or reason for which aircraft gets this special departure frequency and which doesn't.

As pointed out in the question for some reason mostly it is "big" aircraft that gets this preferential treatment, but I am not 100% sure why.


texts: Could a pilot incapacitate other crew/passengers by manipulating cabin air quality/pressure?

texts:
Could a pilot of an airliner incapacitate everyone outside the cockpit by somehow triggering a loss of cabin pressure while simultaneously disarming the airplane's oxygen masks, manipulating the air circulation system to induce hypoxia, or some other means?

For example, would it be a credible theory that the pilot de-pressurized the 777 flying Malaysia Airlines Flight 370 and flew it off somewhere?


texts: Can a fighter jet travelling at fast speed be brought down by a weapon like an M134 Minigun or any machine gun?


texts: What are these 4 spots on the wings and fuselage of the A-10? I can't seem to find a closer shot of their wings but each spot looks like a small target with a dot and an outer circle, mostly in red, but some are in black.


texts: How to calculate coefficient of drag for a particular shape?

texts:
While working on my project I gave my RC plane's nose a particular shape. It doesn't resemble any simple shapes for which coefficient of drag is provided on Internet.
I don't know simulations.  Also I don't have any wind tunnel facility for my project.  So is there any other way,  any website or any formula for computing coefficient of lift and drag?


texts:
This picture of an Airbus A350 test aircraft shows multiple instruments on the flap fairings, wing fairing and on the empennage:

Source: A380_TLS_A350 AIB199GG (high-res version)

They are being described as 'aerodynamic flow cones'.

What are these -- what do they measure, and how?


texts:
The term for moving to a lower altitude is "descending." Why, then, is the term for moving to a higher altitude "climbing" and not "ascending"? The latter goes better with the term "descending."

Does it have anything to do with "ascend" and "descend" sounding similar on the radio?


texts: In almost any airplane commercial operation, unless you’re doing something very short haul daytime ops, an Instrument Rating is all but required with airplanes(it’s even in the FARs). Generally the weather won’t stay nice enough for you not to use it, and most airlines and other commercial operations will avoid VFR all together, leaving VFR mostly for recreational pilots. In helicopters however it seems much different. Even in professional  settings like news services, 135s Helicopter operations, and even essential services like fire rescue,  will try and stay VFR at all costs, and will avoid flying if the weather is not VFR, even if they have an Instrument Rated helicopter pilot. VFR has a lot of limitations that would have a large chance of losing money for a helicopter service. Why is IFR so much more taboo and/or dangerous in helicopters compared to airplanes?


texts: What to look for when purchasing a headset

texts:
I'm currently a student pilot, and I'm starting at an aviation university this fall to major in commercial aviation. Needless to say, I will be flying a lot. I'm looking to upgrade to a nice headset from the pretty basic one I have now, and I'm looking for a bit of guidance. I'm 6'3, so I wouldn't say I have a small head, and I've had problems in the past with headphones feeling cramped on my ears, which I don't want to be the case with my headset. I plan on having this headset for a while, at least all the way through college and hopefully several years after that.

First of all, is noice-cancelling actually that important(in terms of health and comfort)? I know there are a few decent headsets are out there w/o noice cancelling, and they are quite a bit cheaper than noice cancelling headsets.

I've been told about a couple commonly used expensive headsets that are pretty widely used across the industry. However, these headsets are $850+. At this price level, does the price of the headset accurately reflect quality, or is everything more personal preference? What are some of the pros and cons of the more popular headsets, and what should I look for when purchasing one?


texts: Can helicopter or aircraft intro flight hours count towards a private pilot license?

texts:
I'm trying to figure out whether I'd prefer to fly helicopters or fixed-wing aircraft and am taking a few intro flights where the other person lets me fly for a little bit.

Can these hours count towards my helicopter / aircraft private pilot certificate? If yes, do I need a logbook or what kind of proof do I need?


texts: Is this planned building in a runway approach legal?

texts: A 50 story building is planned in Santa Clara, CA three miles from the SJC 12R runway end. Such a building is at least 500ft tall and many such buildings are 700ft or more, is this legal? Nothing around it is more than 100ft tall. Taller than 200ft qualifies it at least as an obstruction.


texts: Where are the first structural damages after maximum speed is passed?

texts:
What 2 parts of the airframe are the first to have structural failure after exceeding maximum speed?

Sorry. I just thought there might be a part that usually failed first.


texts: How do commercial aircraft windshear alert  warning systems work?


texts: How is directional control during takeoff and landing maintained in tailwheel airplanes equipped with skis?

texts:
Reading this question got me wondering: From what I've heard and read about taildraggers, brakes are needed during takeoff and/or landing rolls to maintain directional control and prevent a ground loop. At low airspeeds rudder authority is insufficient to keep the plane going in a straight line.
How is this achieved when skis are mounted instead of wheels? Is there anything special about skis that makes them more controllable  than wheels in these situations?


texts: How is the Angle of Attack influenced in the slipstream of a propeller?

texts:
My question is how can the angle of attack be changed when the wing is in the slipstream of a propeller, giving "enough air flow" to the wing. The propeller sends the flow of air in the same direction related to the wing no matter how the aeroplane is oriented in the space. So theoretically the angle of attack should never change.

UPD: The answer should not depend on how the plane is thrusted. Turbo engines are also pushing the plane in the same direction related to the fixed wing. ( I am not talking about engines that can change the vector of thrust).


texts: Do I need to descend towards the Minimum Descent Altitude if I have the airport in sight?

texts:
I have some questions about circle-to-land approaches.

If we have the runway in sight above MDA, do we need to continue to descend to MDA on downwind? Can we just keep fly like a traffic pattern until abeam aiming point and then start the descent?

Similarly, If during circle to land approach we lose the runway on downwind but we are above MDA, do we need go missed still toward to the runway? Since we are above MDA we should still have obstacle clearance....


texts: What is the effect of fuselage weight on a model glider?

texts: I've built a model glider and wanted to see the effect the weight of the fuselage had on its performance. It flew the further with more weight which seems counter intuitive. I can exert more force into the glider with more weight which results in greater airspeed, would this be the reason for the increased glide ratio? How does this compare to real life gliders? Thanks.


texts: Why does the helicopter's nose go down when the cyclic is pressed forward (in a hover)?

texts:
Helicopters have hinges on top of the rotor mast, allowing the rotor to be tilted longitudinally (forward/aft) or laterally (sideways).

Why does the helicopter fuselage tilt up/down when the cyclic stick is moved longitudinally? It should not be influenced by what the rotor does due to the hinge, right?


texts: Can you breathe with a drop down mask under water?

texts: Say a passenger jet lands in the ocean. Could the captain being the last person to get off the jet use the drop down dry chemical oxygen generators to breathe while checking for passengers? I know they are flimsier so depending on depth they would collapse.


texts: How to calculate flight time from time at full throttle?

texts:
I'm building an electrically powered paraglider,  and I'm trying to reach one hour of flight time.  I've resolved to using 2 18-kilowatt motors. I could use one 35-kilowatt motor, but I'd wrather not kick out my spine on a hard start.

Anyway,  with 6 x 504Wh packs,  I'd get 6 minutes at full throttle.

But powered paragliders don't use full throttle the whole time. How can i calculate aproximate flight time from time that i can have full throttle?

You can assume that my glider has a forward rate of 9:2, and a climb rate of 9:4.


texts:
Why was the Boeing 377 "Stratocruiser" frequently landed nosewheel first on touchdown? In the mid-1950's I had often observed Northwest Airlines' B377's frequently being landed that way at the old Minneapolis-St. Paul airport.

A family friend and PanAm First Officer who frequently flew the SFO-HNL run in B377's told me that (as best as I can recall now) the reason for landing the B377 in that configuration had something to do with help in "setting or unlocking the nosewheel steering" for directional use when the aircraft was fully down on the ground.

As the B377 was Boeing's prototype for the "Stratocruiser", I've wondered if their wartime B-29 "SuperFortress" also was, or could be, regularly landed nosewheel first as well?

And then, during WWII, were there any other tricycle geared two- and four-engined "heavies" that were also meant to be, or could be, landed nosewheel first?


texts: Do headrests considerably increase safety on aircraft?

texts: When looking at newer GA aircraft, for example, Cessna 172s it is very obvious that the seat design has changed quite a lot over time. With the older ones having very short backrests and the newer ones being equipped with quite high seats including headrests the analogy to the automotive world is undeniable. Do the same reasons like impact safety apply to this development? Would it make sense to retrofit headrests for safety reasons?


texts: Does an increase in inlet temperature affect fuel flow and power output?

texts: The fuel flow rate decreases as the inlet temperature of the air entering the engine increases. Will the engine produce same amount of power as when the fuel flow was higher?


texts: Is there a manual which describes the algorithmic procedure on which the Vertical Navigation Guidance is based?

texts:
I am interested in the methods implemented by Flight Management Systems in order to calculate a trajectory path of vertical navigation guidance (VNAV), which takes into consideration the legs of the instrument procedures used for a flight plan, among other things such as aircraft's performance characteristics, wind etc.

In other words, a manual or a guide from official sources (for example, FAA, ICAO or Eurocontrol), but other reliable third-party solutions would also suffice.

I am mainly interested in a way to determine the vertical profile of an instrument flight procedure (SID, STAR, IAP) based on its legs and any crossing altitude or speed constraints that are assigned to any of their waypoints.

Can someone point me in the right direction? I am aware that there is not one way of determining the vertical profile of a route, however my guess is that some universally accepted guidelines must exist.

EDIT: I will provide some more information about what I have in mind, based on Noah's contribution. Let's take for example FINNZ2 and HHERO3 departure procedures of KSNA airport. We can see that some of the waypoints have crossing altitudes assigned.

Can an acceptable implementation of vertical navigation be based on the aforementioned crossing altitudes, by considering them as mandatory altitudes that an aircraft must have while passing from them? This would mean that every such crossing altitude would be considered as "CROSS X AT Y ALTITUDE" restriction, even if it is At or Above, At or Below or Block.

Something like the following vertical profiles:

In other words, I am trying to figure out if this would be a useful or realistic information that an FMS would also provide.

My other idea would be to take a predefined climb gradient for the aircraft, let's say 500 feet per nautical miles and adjust the vertical path if any waypoint crossing altitude restrictions are violated.


texts: How to decide which aerodromes should have Electronic Terrain and Obstacle Data?

texts:
What is the meaning of "aerodrome that is regularly used in international civil aviation"?

Is there any explanation or reference material in support of Aeronautical Information System (AIS)?

I found several things in Eurocontrol document but there is no exact explanation and solution to decide which aerodromes should have Electronic Terrain and Obstacle database.


texts: I have been fascinated with the thought of flying all kind of aircraft on Mars. To begin, I don't know much about the fundamental things or requistes for flying. Is it possible with the the things we currently have? What kind of infrastructure would be needed to fly there? Assuming GPS navigation is already set up there. What would be the design of the aircraft and the runways? Would it be like we have on Earth or completely revolutionised Idea? Kindly not mention the costs of flying there.


texts: How does climb-rate vary with density/pressure altitude?

texts:
I'm seeking to write a little web or phone app which can help me choose the best cruising altitude based upon winds aloft. I know Garmin Pilot (and probably Foreflight) have a cruising altitude selector, but they don't seem to take into account the extra time/fuel required to get to the higher altitudes. I'm looking to make a calculator which factors that in.

I realize that the actual formulae for climb-rate, take-off distance, landing distance, etc are quite complex, but I don't need to generate them from scratch. What I plan to do is start with the charts in the performance section of the POH for a particular aircraft...

...and find some known values for climb-rate for given pressures/temps/weights and use curve-fitting to come up with simple formulae which are still within a few percent of what I would get with these charts.

Of course, to be as accurate as possible, it would be better to know, roughly, how climb-rate varies with pressure-altitude, density-altitude, weight, etc. Some of the adjustments (eg. for weight) seem to be fairly linear (at least over the domain of values of interest to us), while some others seem to have some curve... so maybe they vary as $b^{-x}$, $\frac{1}{x}$, $x^2$, $log(x)$...?

Does anybody know the general way in which climb-rate varies with these factors? (Bonus round: can you do the same for take-off and landing distances, in case I wanted to make a calculator for those?)


texts: Are conditional line-up clearances still valid if the referenced traffic initiates a go-around / missed approach?

texts:
Suppose you are the captain of Big Jet 345:

  Big Jet 345, behind landing Boeing 757, line up runway 27, behind

  Behind landing Boeing 757, line up runway 27, behind, Big Jet 345

Now suppose the landing Boeing 757 executes a go-around. Does the conditional clearance allow you to line up and wait after the Boeing 757 flies over the touchdown point?


texts: How do airline pilots relieve the physical stress and discomfort of sitting for long periods of time?

texts:
Airline pilots are required to sit in the cockpit for quite a considerable amount of time during their day. For example, during the preflight, climb and descend portions of the flight, there are many events going on in the cockpit that requires both pilots' attention. The amount of time they are required to spend sitting in the cockpit is, surely, longer than that of a passenger on the same flight.

How do they relieve the physical stress/discomfort and other physiological issues associated with sitting for a long time? For example, during cruise, is it normal for one of the pilots to unbuckle the seatbelt, get up and stretch his legs in the cockpit? Do they do some simple exercise for a few minutes during the turn around?

Note: This question is not about how pilots deal with the mental stress of boredom in a long flight. This is about how they deal with the physiological discomfort associated with remaining in the sitting position for a long time.


texts: What is the relationship between centre of gravity, centre of pressure and pitch?

texts:
Ok so I've got a couple of questions regarding CG, CP and pitch

1) When the aircraft is taking off, is the tail down force required to pitch up the aircraft high? Because the aircraft always has a natural tendency to pitch down.

2) When the aircraft increases its AoA, the CP moves forward (towards the leading edge). Does this mean it would go ahead of the CG or move closer
to the CG.


texts: How wide would an A330's wingtip vortices be around a minute after landing?

texts:
I recently watched MenTour Pilot's new video about the Royal Air Maroc 737 takeoff from Frankfurt several years ago that made the news at the time because it rotated, failed to fly away at high AoA for several seconds, lowered pitch and settled back to the runway, accelerated some more, and then took off normally.
The original video of the incident is here:

In his video, MenTour Pilot suggests that the 737 was prevented from taking off because of the sudden drop in airspeed from encountering the left wingtip vortex of the A330 that had recently landed on a nearly perpendicular runway. However, the original video seems to show the RAM 737 at high AoA for around 11 seconds after its first rotation attempt. At Vr for a 737, that seems like it should burn through 2,000 to 3,000 feet of runway, depending on weight. (135 kt = 228 ft/s, for example)
So, my question is, how wide is each wingtip vortex of a landing A330 around 1 minute after landing? The conditions appear to be almost calm wind. Would each vortex really be thousands of feet wide by that point?


texts:
As the title mentioned.
And also, is using it in zero visibility (or near) a real life scenario?


texts: What RNP level is required for an RNP approach if the chart does not specify a value?

texts:
RNP (Required Navigational Performance) approaches require the aircraft to monitor the navigation accuracy
within a specified limit, called RNP level:

There are several different levels of RNP. Examples of RNP levels used for approach include RNP 0.1, RNP 0.3, and RNP 1.0 (There are also RNP 4.0 and RNP 10.0 levels that apply in the en route environment). "A performance value of RNP 0.3, for example, assures that the aircraft has the capability of remaining within 0.3 of a nautical mile to the right or left side of the centerline 95 percent of the time."

[...]
The minima line will include a performance value, RNP 0.30 for example. GPS with WAAS can support RNP 0.3 and above.

(faa.gov on Satellite Navigation)
Usually the RNP level is given in the minima section of the approach chart (and according to the above FAA quote, this is always the case in the US).
There are however approach charts that do not include this. Consider for example the following 3 approaches into Innsbruck (LOWI), Austria. While the first example lists the RNP levels, the other two do not:

RNP Z RWY 26 (AR)

There are two different minima for the different specified RNP levels.

RNP E RWY 26 (LPV ONLY)

There is no RNP level specified, also not anywhere else on the chart (as far as I could find). Maybe this is because this approach is LPV only (requires EGNOS1)?

RNP Y RWY 08

Again, there is no RNP level specified and this time there are only LNAV minima. So which RNP level would apply here?

1 EGNOS is the European SBAS (Satellite Based Augmentation System), equivalent to the North American WAAS.


texts: Can an issued landing clearance be replaced with "continue approach"?

texts:
Since the US handles the landing clearance differently, this is limited to Europe (EASA-land).
From Eurocontrol:

Continue Approach
If the runway is obstructed when the aircraft reports ‘final’, but it is expected to be available in good time for the aircraft to make a safe landing, the controller will delay landing clearance by issuing an instruction to ‘continue approach’. The controller may explain why the landing clearance has been delayed. An instruction to ‘continue’ is NOT a clearance to land.

I understand it's also used for sequencing, e.g., continue approach number 2, number 3, etc.

Here's the scenario:
STACK 1 has been cleared to land, and is 8 NM out. STACK 88 was holding short and was requesting sometime to verify something, but now they are ready.

STACK 88: Tower, Stack 88 is now ready for departure.

Tower: Stack 88, traffic 8 mile final, are you ready for immediate departure?

STACK 88: Affirm, Stack 88 is ready.

Tower: Stack 88, cleared for immediate takeoff, no delay.

STACK 88: Cleared for immediate takeoff.

Tower: Stack 1, cancel landing clearance, continue approach number 1, traffic departing, minimum approach speed.

STACK 1: Roger, continue approach, minimum approach speed.

Is the above exchange correct? In terms of both procedures and phraseology, i.e., can a landing clearance be cancelled for reasons other than a go-around instruction?


texts: What is this delta wing aircraft parked at NASA Ames Research Center at Moffett Field?

texts:
What is the aircraft shown at these coordinates? https://goo.gl/maps/VTc153EacEL2

This is at NASA Ames Research Center at Moffett Field. Per the Ames map it is located north behind building N-127 (Warehouse) and west of the VTOL pad.

It has a dome canopy and a delta wing configuration. It is approximately the size of a fighter aircraft. A very blurry picture of the tail is visible by using Google Streetview from the Moffett golf course and looking west across runway 41R.


texts: Really love aviation but have a computer science degree. What kind of jobs could I possibly get which involve aviation?

texts: I really want to work in the aviation industry. Is there any way I can put my computer science degree to use in this industry.


texts: When must a pilot report Negative Contact?

texts:
Which regulation or AIM section specifically states when a pilot is required to report negative contact?  It appears that different airports in the US have slightly different expectations.
My understanding is that ATC is only relieved of separation requirements when the pilot says "Traffic in Sight". However, if ATC says "Cessna 123, Number 2 following traffic on downwind", if pilot says "Number 2 following traffic on Downwind, Cessna 123", that is the same as saying Negative Contact. In other words, unless the pilot says the magic words "Traffic in Sight", ATC treats anything else as negative contact. Until the pilot reports traffic in sight, or ATC says "Report Traffic in Sight", it seems like unecessary radio traffic for pilot to report negative contact, unless specifically asked by ATC.
Also, what do tower controllers think about this?


texts: Why doesn’t the minimum drag point meet the point at the best Cl/CD polar?

texts: On the first picture, it shows that the minimum drag point is exactly the same as the maximum L/D ratio where it also supposes to be at The point as it shows on the second picture. However, according to the third picture, it doesn’t look like the minimum drag point is at the maximum L/D on the second picture. Why does this happen?


texts: Why are passenger required to put their phones in Airplane Mode during taxi to gate?

texts:
Why do airlines require that phones remain in airplane mode during the final taxi to the gate after landing? As far as I can tell, it does not affect the airplane or anything else negatively or at all. Is this true? If so, then what is the point in keeping the phone in airplane mode until the cabin doors open? Is it just for the sake of convention?

Thanks a lot in advance for any responses!


texts: Does a Stalled Wing Exhibit No Circulation

texts: If a wing is stalled, will the wing not exhibit any circulation as predicted by the Kutta-Joukowski theorem?  If so how would this affect the pressure distribution between the top and bottom portions of the wings?  Would the top portion of the wing (low pressure) carry most of the lift?


texts: When does a turbine need to go to maintenance?

texts:
I'm wondering what the limiting maintenance factors for engines, for example of an A320, are. Of course this is something that is different from one engine manufacturer to another and especially from engine type to another.

But what rules are there for regular, operation driven, maintenance?
Please consider engines of any type, used for a mid-sized plane like the A320 on commercial passenger flights.


texts: Does turning off WAAS turn off ADS-B out as well?

texts:
I'm a CFII and for training GPS approaches with advanced students, I like to occasionally turn off the WAAS receiver on the 430/750/G1000/etc. when they are not looking, to simulate a WAAS failure and make them notice they need to change their minimums.

Now, ADS-B out depends on a WAAS GPS-receiver. When I intentionally turn off WAAS, does that turn off ADS-B out as well? Would I be technically non-ADS-B-compliant in 2020, when flying the approach without WAAS?


texts:
This question might seem strange as almost all aircraft have the air flowing over the wing in only one direction. However if you wanted to design an airfoil would have a good L/D in the forward flow direction, but would also generate lift, or at least not have excessive drag under reverse flow conditions, how would you go a about finding such an airfoil?

The Aerobie flying disc uses an airfoil that looks like a fish. The fish tail creates stability in a spinning disc, but also quite a bit of drag I believe. If stability is not a concern, I think another airfoil shape may provide less drag.

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

http://www.aerobie.narod.ru/aerobie.htm


texts: Is there any equation on propeller thrust that takes into account the number of blades

texts:
I had a look at both

What is the equation for calculating static thrust?

and

Is there any equation to bind velocity, thrust and power?

However, it does not mention how much would the thrust be affected by the amount of blades. e.g if it was a 20 blade propeller with a given RPM, how much would it affect the amount of thrust

Could you please kindly help me with this? Thank you


texts: Which is the technically correct term: Nose Gear or Nose Landing Gear?

texts: Talking about landing gear system, came across my mind the correct and technical name. Is it NOSE GEAR or NOSE LANDING GEAR?


texts: Can large airliners do aerobatics such as loops?

texts:
This subject has been partially covered before here Is it possible to do a barrel roll in a large aircraft like a B737? and here Is it safe to roll an airplane that isn't approved for it?

If a airliner such as say a 777-300 had enough height, could it theoretically do a loop or similar aerobatics?

I am supposing that there is no passengers, luggage, hostesses and minimum fuel on board etc - so minimum weight.

Also, taking into account the loop - if it couldn't achieve the loop by pulling up - could it achieve it by going nose down instead?

IE: The aircraft goes nose down till it is upside down then pulls up - a mirror version of a normal loop basically.

The other questions go over the reasons why not to roll a large aircraft, I want to know if other aerobatics (specifically loops) are theoretically possible.


texts: Where can I get a reliable and a updated Airport API or Airport Database, and I also want to know the charges for the API?

texts: Kindly guide me where can I get a reliable and updated airport Master API. The airport API should have all the information about all the airports in the world and I also want to know how much do they charge for the API.


texts: Are aviation accident investigation reports always made public?

texts:
How is the dissemination of aviation accident investigation reports regulated? Are the reports public by default, or can they be kept secret? Are there any known rules on this?

If the reports are not public, do the people involved in the accident have a right to access the evidence and/or the reports? Can they find out what the verdict (if there is one) was?

This surely depends very much on the country. Please indicate the regional scope of your answers. (My interest is specific but not limited to France.)


texts: Russian cockpits were often painted turquoise to reduce pilot fatigue. So my question is why most non-Russian cockpits are painted gray, or in the 777's case, tan?


texts: Are the PW1100G and PW1400G engine series not certified by the FAA?

texts: I was digging around the FAA type certificate data sheet (TCDS) database and I could not find the entries for the PW1100G and PW1400G engines series. I then went to the EASA TCDS database and both of them were categorised under the PW1100G-JM title. Have these two engine series not been certified by the FAA? Was it because they were for European aircraft OEMs (PW1100G for A320neo, PW1400G for Irkut MC-21)?


texts: How should I make a downwind departure from a towered airport?

texts:
I'll be departing from a towered (Class D) airport, and I need to make a left downwind departure and turn right off the downwind leg to exit the pattern.

I've done this with a CFI, and I've also made left crosswind departures, and each time I climbed at full power above the traffic pattern altitude (TPA) while still on the downwind/crosswind leg, and I exited the downwind/crosswind leg whenever I felt like it.  I never really thought about whether I needed to stay at TPA all the way to the end of the leg, or whether I needed to complete the leg before exiting.

Do I need to stay at TPA while in the pattern, or can I climb above TPA since I have told the tower I plan to depart?  And when can I leave the pattern?


texts: What are the must-checks for purchasing an airplane?

texts:
I've always dreamed of buying my own plane. Turns out, they can be had for $20,000 on eBay.  This sounds too good to be true.

What checklist of items are essential to prevent my new purchase from falling out of the sky?


texts:
Based on this other answer, a new question arose.
When is runway slope most important, at take-off or at landing? Or is it equally important in both flight phases?


texts: Why Clyde P. / Boeing B-52H Stratofortress flight from 1962 took the longer route?

texts:
Third on list of longest non-stop, non-commercial powered aircraft's flights is January 10–11, 1962 flight on Boeing B-52H Stratofortress made by major Clyde P. Evely and crew. Can anyone provide any details about this flight?

Wikipedia says, that it was a flight from Japan (Okinawa) to Spain, via Tokyo, Seattle, Fort Worth, Washington and Azores. I'm especially interested in knowing, why that way? Most (all) of today commercial flights are flying Europe to Japan / Far East the opposite way, that is through Asia.

Is there any source of information, why did that flight took the longer route? Was that specially made to break the world record or was there any other circumstances to take such decision?


texts:
(Source left, right)

How does the Mil Mi-35M compare to the Boeing AH-64D Apache?

Both are attack helicopters. I have the following concerns with the Mi-35M:

When compared to the largest U.S. attack helicopters (like the Apache), it looks quite heavy.
It has a cargo compartment that seems to have no use. Looks like the Soviet design was retained to avoid massive redesign.
It doesn't have a reinforced 'cheek' like the Apache does to protect it from bullets of larger caliber.
It doesn't have a mast-mounted radar like the Longbow has. Looks like fire-control is manual.

How do they compare?


texts: Why is it, with less airflow, you'll have less control effectiveness?

texts: I understand the principle of less airflow, less control, but why is that the case?


texts: Is Auto Pilot capable of performing TCAS resolution advisory?

texts: I just watched a near mid-air collision video clip on Youtube. When AP is on and TCAS gives resolution advisory ("climb climb" or "descend descend"), does AP automatically perform the advisory if the pilot doesn't take over in time?


texts: What means of navigation did commercial Soviet airplanes use in the 50s-90s?

texts:
Nowadays, practically all Western commercial airplanes use some kind of GNSS/GPS as primary means of navigation, sometimes paired with inertial navigation systems and user-friendly computer interfaces (FMCs). This allows planes to follow very precise routes in long flights, also shortening flight times by flying more "direct" routes. Before the 1980s and the use of GPS in civilian aircraft, instrument navigation was pretty much all about VOR/DME/NDB.

How about the Soviet aircraft built between the 1950s and the 1990s? How close were the Soviet navigation systems to the Western ones, and what were the major differences?
It's common to see a "navigator" position in Soviet aircraft cockpit videos. Was it so complex that it required an extra crew member?
Did the Soviets ever get to use GPS navigation or at least FMCs in their planes?


texts: Can an A&P who is also a private pilot receive compensation for conducting maintenance test flights?

texts:
Related to this question.

Suppose a repair is made to an airplane and a maintenance test flight is required. Suppose the A&P who works on the aircraft is also a private pilot. That person performs the test flight and then signs off the repair.  (assume USA)

A private pilot can't fly for compensation or hire.

Can the mechanic bill for the time she spent flying?  Are maintenance test flights considered incidental to a mechanic's business?


texts: Would a wingtip stall still be bad if there was no aileron there?

texts: If there was no aileron on the wing tip, would a tip stall still be bad compared to a root stall?


texts: What would FAA controllers be referring to when mentioning "code 0027?"

texts:
In the second video on "You Need To Hear These FAA Tapes From That Oregon UFO Incident That Sent F-15s Scrambling," you hear controllers mention a code 0027. If the target in question had a transponder, the content of the article is misleading. Does anyone know if code 0027 refers to something specific in ATC terms, or are they just referring to a transponder code?

Here's the full link to the article. http://www.thedrive.com/the-war-zone/18473/faa-recordings-deepen-mystery-surrounding-ufo-over-oregon-that-sent-f-15s-scrambling


texts: How much does it cost if someone falls ill before take-off?

texts:
A month or so ago, I flew from LHR to Australia, via Doha, on a Qatar Airways A380. Just as we were about to enter the runway at LHR, the captain announced that someone had been taken ill on the plane, and we'd be going back to the gate. That delayed take-off by (I think) about an hour, and required topping up the fuel tanks.

How much would this have cost the airline? Are there any circumstances where they would pass the cost onto the passenger who fell ill?


texts: How is turbine engine oil pressure associated with turbine engine speed?

texts:
I've seen scenarios where engine oil pressure can be used to indicate if turbine engines are performing correctly at intended speed.

How exactly is this associated?

I'm not certain, but if I had to guess; the EDP (engine driven pump) from engine startup would eventually increase flow rate of engine oil as the engine speed increases, thus more flow to the pressure regulator which increases oil pressure?


texts: As at 2020, why don't fighter jets have ≥ 200 rounds for their cannons?

texts:
I already read Why do fighter jets still have guns/cannons?, but it doesn't expound why 100-200 rounds suffice or how "6 seconds is actually a lot of 'gun time' for modern air-to-air systems considering speeds, targeting systems and lethality of the projectiles involved."

I acknowledge that "It's not like WWII anymore where you'd slowly pull up behind a bomber and then have to spend several seconds pumping a bunch of crappy .50-cal lead in, hoping to poke enough holes in an oil cooler to make a difference."
Revolver cannons
"The Mauser BK27 is a 27mm calibre [revolver] cannon manufactured by Mauser (now part of Rheinmetall) of Germany. It was developed in the late 1960’s for the Multi Role Combat Aircraft programme that ultimately became the Panavia Tornado, it is used on a variety of aircraft including Typhoon, which carries 150 rounds."
"For that role the [SAAB JAS-39 Gripen] aircraft is armed with a 27 mm Mauser BK-27 revolver cannon with 120 rounds and with up to six short-range AIM-9 Sidewinder air-to-air missiles."
Rotary cannons
"The F-35A is armed with a 25 mm GAU-22/A rotary cannon mounted internally near the left wing root with 182 rounds carried". The Dassault Rafale fighter
"is equipped with the GIAT 30-millimeter cannon with 125 rounds of ammunition."
MiG-35 "is also armed with the 30 mm Gryazev-Shipunov GSh-30-1 autocannon with 150 rounds.". "The Su-35's armament includes a GSh-30-1 30mm autocannon with 150 rounds".


texts: What are the correct procedures for military aircraft interception over international waters?

texts:
I recently read this list of errors in the film Top Gun.  The list is long and fairly well done, but there is one I realized when thinking about that movie and that is Maverick may have actually caused an international incident at the start of the film that precipitated into the climactic dogfight at the end.  That is, they intercepted the MiGs at the beginning of the film in an unprofessional and hostile manner which is not used when intercepting another aircraft over international waters.

Aircraft interceptions are a common occurrence in international airspace but there are specific procedures involved and protocol used to avoid an international incident.  Typically a two ship flight will maneuver alongside an unknown aircraft to visually identify it.  Any additional actions ie creating a collision hazard from a head on cross or hard maneuvering onto an aircraft’s six then tracking it with a fire control radar, as Maverick does at the start of the movie can be interpreted as a hostile act and could actually warrant use of force.  Therefore Maverick may be the aggressor here and the second MiG maneuvering for a shot at Cougar and lighting up his F-14 with its fire control radar would be a reasonable response to the F-14 two ship’s aggressive act over international waters.

  Goddamnit, Maverick!

Soviet aircraft routinely approached US carrier battle groups during the Cold War, in some cases coming within 1/2 mile from the battle group.  They were intercepted on a regular basis but never in such an aggressive manner as is shown in Top Gun.  Unless said Soviet aircraft were acting in a provocative manner with posed a direct threat to the ship or the air wing aircraft, there really wasn’t much you could do as you were in international waters and subject to international law.  Doing otherwise would have been an act of war.

So am I wrong in this assessment?  Is the intercept of an unknown aircraft as shown in the movie uncalled for and hostile to the MiG pilots who were only engaged in their own maneuvers over international waters?  Can anybody shed further light as to how the USN would professionally intercept a bogey over international waters?


texts: How does a pilot make sure they have received all applicable NOTAM's?

texts: I've always wondered how a private pilot makes sure they have read all the NOTAM's that might affect their flight. There must be thousands of NOTAM's out there. This question talks about the many types. Some will be just for the day, some applicable for months. Some affect large areas, some just one taxiway. If doing a cross-country flight, especially to an unfamiliar airport, how does one know how to wade through all of them and be sure they've covered all of those that might affect their flight?


texts: Relationship between flapping and lagging frequency

texts:
In my rotorcraft module at university, we were told that blades leading/lagging is as a result of blade flapping. To conserve angular momentum, an upward flapped blade (CG moves toward rotor hub) will speed up and hence "lead". A downward flapped blade (CG moves outwards) will slow down and hence "lag". I understand this, however if the lead/lag was as a direct consequence of flapping, then shouldn't their frequencies be the same? In the above image (Shown to us in lecture) you can see that the lagging frequency is roughly 1/5 of the flapping frequency. How is this possible? If the blade lag is a direct consequence of flapping surely this is not possible.

Are there more factors that affect lead/lag? Perhaps cyclic pitch control alters the drag of the blades and hence affects the lead/lag? Or could it be to do with the hinge and any associated damping effects.

A comprehensive explanation would be appreciated.


texts: What could be the reason for a feeling of speed oscillation after takeoff in a 747?

texts:
Took off from LHR in a B747-400 on Sunday and I experienced something new that is puzzling me.

After take off as the aircraft was climbing it seemed to continually speed up and slow down at the rate of once every one or two seconds. Kind of like an oscillation in the direction of travel.

After a few minutes of this it stopped.

What caused this to happen?


texts: How do modern avionics work without vacuum pumps or gyroscopes?

texts:
I'm going to be taking my checkride soon on a Skycatcher 162. It has an all glass cockpit utilizing the Garmin G300, and its my understanding that it does not utilize gyroscopes or vacuum pumps for any of its instruments.

Seeing that if I were in something like a Cessna 172L, which uses both gyros and vacuum pumps for many of its instruments, questions such as "how does the attitude indicator work?" are fair game, I assume that the same questions are fair game for avionics like the Garmin G300.

The problem, I don't know how they work and its looking like the top google result for "garmin g300 gyroscope" returns a 404 error.

Also, do digital pitot/static systems work in essentially the same way as the old school ones in planes like the C172L? I'd hate to tell my examiner anything along the lines of "I have no idea".


texts: Is there any electrical component on an aircraft which can never be turned off by a pilot?

texts: Am I correct to assume that every electrical system on an aircraft can be manually switched OFF/ON by the Pilot OR is there indeed any system, on which the Pilot does not have the ability to switch OFF/ON ?


texts: If a beginner paraglider / paramotor wing fully stalls, how much vertical distance is needed for recovery?

texts:
In paramotoring, a beginner wing is a wing with A, B, C, D and F (brake) lines.

When a full stall is induced, a pilot may fall a long, long ways before the wing will recover, and most will need to plan for it.

On a calm day, what is the vertical recovery distance for a beginner wing?

As an example, one could use the Gin Bolero 6


texts: What are these protuberances on the north edge of runway 10/28 at Mataveri?

texts:
The single runway (10/28) at Mataveri International Airport (IPC/SCIP) on Rapa Nui1 has (at least according to Google Maps) a few paved protuberances emanating from partway down its northern edge which serve no obvious purpose:

I wondered if at least some of them might be the old turnaround pads from before the runway was lengthened in the early 1980s, but:

if that were the case, one would not expect them to still exist in what at least appears to be good condition a third of a century later, and
they look far too small to be turnaround pads emeritus - compare, for instance, the turnaround pad at the approach end of runway 28:

Does anyone know what these appendages are, and what purpose they serve?

EDIT: As @MikeSowsun points out, the runway would not only have been shorter then, but narrower as well (not having needed to serve widebody jets or distressed spacecraft), meaning that the turnaround pads themselves could be smaller, and that they'd have been at least partly paved over when the runway was widened (leaving only the outboardmost portions visible); this still doesn't address the issue of "how come they're still visible a third of a century after being abandoned", though.

1: Also known by its colonial names of Easter Island and Isla de Pascua.


texts: What are the rules for right-of-way on final approach: by aircraft category or only by height?

texts:
I'm a student pilot studying right-of-way and confused about the landing provisions. Right-of-way is determined first by aircraft category, and then by position. That makes sense.

But the last provision, on final, says the lower aircraft has the right away. Does that mean that the lower aircraft regardless of the category has the right-of-way, or does the lower aircraft only have the right-of-way when they are in the same category?

For instance, if a glider was on final but high, and a Cessna 172 was on final but lower/closer, who would have the right-of-way?


texts: Why do flight schools refuse to tell me the price of a course?

texts:
I have searched many flight schools' sites in my area and none mentions prices, I tried to contact by email and later by calling them, but they still won't tell me the price, why is that?
Shouldn't I know they price before I decide to do it?
Especially during a pandemic, they should definitely discourage you to pay meaningless visits to the academy for information on the cost and tell you right away?
Why do flight schools do that?


texts: How accurate is XFoil / XFLR5 at 'kinda high' Reynolds numbers?

texts:
How accurate is XFoil/XFLR5 at Reynolds numbers between 2 million and 10 million?

From my understanding it's only accurate at lower Re values.


texts: How do ground effect vehicles perform turns?

texts:
Considering that Wing-In-Ground-Effect (WIGE) vehicles fly with a rather low ground clearance, there is not much room for banking. How do WIGE vehicles turn? Do they turn just very slow with a low bank angle? Or do they turn uncoordinated with wings level?

I can imagine that banking has an opposite effect: the raised wing has less ground effect so more drag so it creates some countering yaw moment. Is this correct?


texts: Can we eliminate the center tank of large passenger planes?

texts:
This is a safety question about fuel and fires. This all regards commercial aviation for large passenger planes.

Most fuel is stored in the wings, but in the largest planes, there's also a center tank for the longest flights. It's this center tank I'm concerned with. In the event of a fire, this seems to be the most dangerous tank.

I'm obviously concerned with fires in the fuselage, or very close to it. Obviously this is where all the people are and we don't want smoke or flame there, but remember also there are overhead oxygen canisters that if heated or fueled, will explode.

Jet fuel is flammable by its nature. This cannot be changed because its purpose is to combust in an internal combustion engine. So it seems the best we can do is to keep the fuel as far from the fuselage as possible, to make it unlikely that fuel will cause a fire there (initially).

Isn't there someplace we can move this center tank? Some ideas I thought of: store fuel in anti-shock bodies on the wings (or they could be just small sears-haack bodies on the wings); store fuel in the empannage; store fuel in nacelles that have a larger diameter than the engine itself, to make room for fuel.

Another exotic idea: Is it possible to engineer the wing such that the most likely structural failure will happen first near the wingtip rather than the wingroot? This would spill the fuel farther from the fuselage. (I got this idea from a really wierd Boeing 747 crash in Netherlands where one engine jumped off then fell back into the other engine, causing 2 engine losses. They said some pins were designed to fail first for a more "benign" failure, but apparently those pylon pins were engineered wrong.)

There's one more tricky caveat, though: the cross feed line to balance fuel loads in the wings. If we eliminate this line, we increase the dangerous consequences of a fuel imbalance. But, it's interesting to think of what might cause a major fuel imbalance other than a leak, in which case the cross feed valve should not be opened. I can't think of anything so I'm leaning toward the opinion that this line can be eliminated too.

EDIT: Thanks to bodargpd for pointing this out. Losing an engine in flight means the consumption rates will be hugely different. Without a cross-feed line, all that fuel in the other wing is unavailable and we may have to ditch early. So the cross-feed line is still necessary. I still say this is much less dangerous than a center fuel tank, however. It would also be nice if we engineered the cross-feed line to be weakest at the sides, so any leak will most likely be as far to the outside of the fuselage as possible.

To sum up, the basic question is, can we viably move the center tank volume of fuel somewhere outside the fuselage?

EDIT: I'm not primarily worried about fuel explosions. I'm concerned mostly about fuel leaks during hard emergency landings. I'd rather have a fuel leak out on the wing than in the fuselage.


texts:
I was on a tour at the University of Maryland, and I saw these wings sitting against the wall:

I asked the guide, and he had no idea. (In case you can't tell these are two wings. The green lines indicate the extent of the two wings.)

What aircraft do these belong to?


texts: How are the limits of the center of gravity chart established?

texts:
When one views a center of gravity limit chart, in this case a C-182T chart, one notices that the forward C.G. line has two small bends in it, one around 2250# mark and the other around the 2675# mark. Why the two bends in the forward C.G. limit line? What has happened at these two points?

Image from: C-182T POH pg. 211


texts: How airplanes of new generation communicate with ATC over remote areas? (North Atlantic Region)

texts: How new airplanes get in contact with ATC while flying in remote areas? Do they use VHF datalink (VDL) ?


texts: What devices measure EPR & RPM on a turbofan engine?


texts: How does an inoperative Anti-Skid affect V speeds?

texts:
I am trying to figure out why is it that when you have an inoperative anti-skid system, the calculated V Speeds are lower?
I'm trying to see this from a performance perspective, could this be due to the brake energy limitation of the aircraft?


texts: What do the green, white and yellow bands mean on an airspeed indicator?

texts: what are these  green and white and yellow bands in the Airspeed Indicator use for ?