# All Questions

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### How to calculcute variation and compass deviation in this CDMVT problem?

Usually I can solve CDMVT problems, but sometimes I feel I'm missing something important. For example: I'm able to solve: Given WCA -012, TH 125, MC 139, DEV 002E. What are TC, MH and CH? ...
98 views

### Why are shockwaves allowed different angles at different distances from a body?

It's been (well) established that a shockwave can only be at the angle of the Mach cone. (I now understand this part). However, in this picture: you can see that the shock is at 2 angles. I also ...
• 2,676
36 views

### Are the spring constant and damping coefficient of landing gear publicly available?

I'm trying to find the spring constant and damping coefficient for a Cessna 172. I looked through the POH, but couldn't find them anywhere. Are these values available publicly in some design document ...
• 245
252 views

### Dyke Delta dynamics?

I recently came across the Dyke Delta, designed by John Dyke. It is a delta wing (more like diamond planform) homebuilt. I'm curious about how this airplane handles, considering delta wings have some ...
56 views

### Why will a slower moving parcel of air above a wing create drag in non-inviscid flow?

This answer explains why a thicker boundary layer will cause a type of form drag. It uses inviscid flow to explain this. It is a great answer, but I can't seem to see how this applies in a real world ...
• 2,676
150 views

### What percentage of airliners today operate with unaugmented GPS equipment?

Responding to this question there was some discussion on GPS equipment and whether it used augmentation (WAAS/SBAS/GBAS) or not. What percentage of airliners operate with unaugmented GPS equipment? ...
• 20.7k
140 views

### ILS Designated Operational Coverage (DOC)

During a standard Instrument Landing System (ILS) approach, I typically arm the VOR/LOC (Boeing 737) to capture the localiser1 once on an intercept course. Upon clearance for the approach, I then arm ...
• 2,653
1 vote
308 views

### How do the landing gear support so much mass?

The first thing that one notices after seeing an aircraft, is that it's quite a heavy flying machine. And so, one would expect monumental tires on these vehicles, yet they don't exist. How is it that ...
1 vote
169 views

### How are military aviators call signs made?

Military aviators always have a call sign that they are referred to as. I would like to know how they are picked? Is it their personality, surname or what?
5k views

### Why do airplanes sometimes turn more than 180 degrees after takeoff?

Why do sometimes (at least in commercial flights) airplanes do a more-than-180-degrees loop after takeoff, in order to aim at the target direction? See image for an example. I guess that it is part of ...
158 views

### Is there any version of CFM56 with can combustors?

This lamp is sold online: They claim it's made from a CFM56 combustion chamber. It looks like a can combustor, and I read everywhere that CFM56 uses an annular combustor. Is there a version of CFM56 ...
• 203
350 views

### Which underwater crash sites of medium to large aircraft have been captured in sonar imagery?

For which crash sites of medium to large aircraft are sonar images available ? Scope: The crash site should already be confirmed (not speculated). For the purpose of this question, let's define "...
• 3,474
1 vote
90 views

### Twin engine or single engine with parachute, which is safer?

Statistically speaking, if we compare two airplanes: a twin engine (like the Beechcraft Baron) VS a single engine with a parachute (like the Cirrus SR22), if we add up all posible emergency events(...
• 3,337
87 views

### Flying N-registered Aircraft in the EU (as an EU resident)

Until recently, I believed what the old, wise men of my local flying club had been telling me for years: You can fly N-registered aircraft in Europe... as long as you have an FAA license. I recently ...
• 1,704
62 views

### How does a thickening boundary layer create form drag?

Imagine a normal wing with flow over it, and to simplify things it's at 0 AoA. Drag is being made mainly because of form drag and skin friction drag. I'm not sure on this, but I don't think there ...
• 2,676
166 views

### A question on stalling and flat spin - in gliders

Very short version: Do gliders do stalls, and flat spins, as aerobatic tricks (as do say aerobatic biplanes). -- As I understand it, with an aerobatic plane, a pilot can and does, for "fun" ...
• 1,932
154 views

### What's the precision difference between ILS and GPS(LNAV/VNAV)?

What is the precision/accuracy difference between both GPS (LNAV/VNAV) and ILS?
• 3,337
3k views

### Vintage photo, Seatac airport

I’m spending the night in a hotel at Seatac Airport in Seattle, Washington, USA. The vintage photo below is hanging on the wall of my room. I recognize the airport as Seatac, circa 1950’s. The photo ...
• 521
151 views

### How did the Concorde’s glide ratio vary from takeoff to supercruise?

I can't seem to get straight numbers on its glide ratio. One source claims 4:1 at takeoff and 12:1 at transonic speeds. But what about the supercruising phase that it's flight was optimized for?
2k views

### How do planes deal with excess lift at high speeds?

If I understand correctly, wind force increases quadratically as airspeed increases. Therefore, all other things being equal, lift should also increase quadratically. Does that mean, a plane going ...
182 views

### What limits automated direction finding from working over oceans?

Automated direction finders are only reliable in relative close proximity to NDBs, due to various adverse effects. In particular, the night effect limits their useful range for navigation ...
• 261
114 views

### Do vtails need twin horizontal trim tabs?

Do vtails need twin horizontal trim tabs? As vtail aircraft don't have a separate horizontal tail, do they need a trim tab on both rudervators?
• 1,393
2k views

### Was radio navigation used for oceanic crossings before GPS? If not, why not?

As far as I understand, before the availability of GPS and other GNSSes, airplanes crossing large distances over water, beyond the range of ground-based navigation aids such as VORs and NDBs, largely ...
• 261
125 views

### How does the air molecules provide wing lift force when only wing is moving or when only the air is moving?

We use to calculate lift force of a wing as function of air speed squared. We can imagine 2 different situations: 1 - the wind has speed thus kinetic energy and momentum while the wing is stationary 2-...
99 views

### How do you communicate with atc and how can they communicate with you when you change frequency?

How do you let atc know that you are going to a different frequency and how will you be able to talk to them if they need to talk to you will they go to that frequency that you went to?
132 views

### What's gonna be the physics behind building 'futuristic' airplanes? Use physics formulas or even theories to answer this question [closed]

After thinking about these 'futuristic' airplanes, I wonder if there's any special physics theory or law behind them. I wonder how faster they can be, persevere more and fulfill the aviation's lover ...
162 views

### What aircraft used this compass?

I was wondering if anyone had any info on this compass I have.
1 vote
154 views

### Why don’t closed wings eliminate tip vortices?

It’s clear that tip vortices never really can be prevented, but why doesn’t a closed wing do that? There is no ‘tip’ on a closed wing so where does the air go to make a vortex? On a normal plane the ...
• 2,676
1 vote
153 views

### What frequencies can you freely speak on? [duplicate]

Are there any frequencies that you can use to communicate with your family at home when you are flying and for a wokie talkie I am wondering if there are just any frequencies that you can speak freely ...
6k views

### Is it possible to tell what aircraft this is?

On a flight a few years ago, I got this picture. Is it possible to tell the aircraft by just this image? I’ve found a few similar but they are a bit different than this one. Someone I was with said ...
• 2,676
189 views

### When ATC tells you to climb or descent now, do the speed restrictions on SIDs and STARs still apply? (EASA)

I am flying the ELSUP 1H departure. After taking off, I get told to climb to FL100. Do I have to comply with the speed restrictions? Is it the same for a STAR?
• 63
257 views

### Why would the F-16 pilots chasing Flight 93 on 9/11 have needed to ram the airliner?

I realize that this is an old topic, and some elements seem to have been answered in the question below. However, one of the two F-16 pilots who scrambled to intercept United 93 just retired from the ...
1 vote
100 views

### How to determine dihedral angle?

How to determine dihedral angle for a high wing ga aircraft with 12' wing span? While there are formulas for determining size of the vertical and horizontal tails, I have yet to find a simple formula ...
• 1,393
33 views

### What is the size of a clam shell drag rudder compared to a conventional rudder?

What is the size of a clam shell drag rudder compared to a conventional rudder? This is for a ga aircraft.
• 1,393
1 vote
96 views

### Why does the Varieze need a metal wing connector?

Why does the Varieze need a metal wing connector? If the Varieze has Fibreglass wings and a center spar, why is the connector made of cast metal?
• 1,393
233 views

### Do airline pilots prepare and are aware of possible emergency landing sites around airports they are taking off in case of complete engine failure?

Do airline pilots prepare and are aware of possible emergency landing sites (like farm fields, wide highways, lakes etc.) around airports they are taking off in case of complete engine failure at a ...
141 views

### How are cockpit warning sounds recorded/chosen?

I know that during an emergency, sounds in a cockpit such as "TERRAIN PULL UP" are played or in some planes the stick shaker takes place during a stall. But how are such warning sounds and ...
1k views

### Gap between F22 ailerons and flaperons

You can see in the below picture that there's an F22 on approach (I think) and this is almost a perfect bottom view of the plane while it's going straight, it isn't banking. There's gaps between the ...
• 809
96 views

### Lateral Stability- Why aircraft will not return of its own accord to the original heading after a sideway gust?

I am reading the Stability section of FAA it says: If an aircraft is flying in a straight line, and a sideward gust of air gives the aircraft a slight rotation about its vertical axis (i.e., the ...
1 vote
93 views

### why does the bottom of a 737 - 800 engine look slightly flat? [duplicate]

The 737 - 800 is one of my favorite airliners and so I've always noticed that it's engines look a bit flat on the bottom, I haven't seen any other airliners do this so, is there any specific reason ...
48 views

### Density altitude difference (formula and Asa CX-3)

I am trying to figure out Density Altitude problem from the book and I get one answer by hand and another with CX-3 and cannot find the bug. So problem goes like this, Indicated Altitude 5250 feet ...
49 views

### Why will the flow turning angle be 0 (or close to) inside of the Mach cone?

(Disclaimer : This probably seems like my 56th question on the same topic, but this will be my last relating to Mach cone angle and shock angles, as I think I understand most of the topic) So the ...
• 2,676
159 views

### Circling aircraft [closed]

Hi guys I'm a newbie here, so apologise if this has already been answered. I'm in The UK and since 2020 RAF aircraft have been circling my city, and have noticed after that it is happening in other ...
1 vote
53 views

### Why are some of the boxes with VOR information thick (like IST VOR) but some of the boxes are thin (like UHM VOR)?

Why are some of the boxes with VOR information thick (like IST VOR) but some of the boxes are thin (like UHM VOR)?
• 2,217
1 vote
108 views

### If sweep angles are high enough can supersonic wings use thick, rounded airfoils?

In lectures on aerodynamics, it's always emphasized that the effect of sweep is to lower the Mach number normal to the leading edge. In the context of supersonic flow, this ensure that the leading ...
• 974
122 views

### Meaning of “G” in aviation [duplicate]

The Singapore Ministry of Transport just published the preliminary report for SQ flight 321 yesterday (https://www.mot.gov.sg/news/details/transport-safety-investigation-bureau-preliminary-...
3k views

### What is a "rapid changes in gravitational force"

I've been reading an article on the BBC Website about the 21/May/2024 incident on Singapore Airlines. According to this article: "The rapid changes in G over the 4.6 seconds duration resulted in ...
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263 views

### How does rudder braking work? [duplicate]

I've always been unable to understand how rudder braking/toe braking works and how you steer while using rudder braking. Hence I came to this website with possibly the most knowledgeable people I ...
195 views

### Could a propeller system for airplanes with automatic, cyclic blade-pitch control that is designed to counter p-factor be practical?

Considering that P-factor is a result of differing angles of attack of the blades on an airplane's propeller, I would imagine that if there was a design that could control the pitch of each individual ...
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