All Questions

Filter by
Sorted by
Tagged with
0
votes
0answers
3 views

Clarification on the SEATAC VFR map

I've been looking at the SEA-TAC VFR map, and something caught my eye... On this map one can see that the SEA-TAC airport has a class B designation in a strange inverse-rhomboid shape, surrounded by,...
0
votes
0answers
17 views

How does the F-16 achieve negative stability?

F-16 has negative stability at subsonic conditions. How is this achieved? To me it looks like a very streamligned, very normally shaped aircraft. Is the Center of Mass actually behind the Center of ...
1
vote
0answers
20 views

How can a touchdown zone RVR report for one runway be different than the rollout report for the runway going the opposite direction?

I saw an RVR report in KSEA where 16C was 800 1200 1800 (touchdown zone, midpoint, rollout), and 34C was 1800 1200 300. I always thought the same scatterometers used for the rollout side on runway as ...
0
votes
0answers
9 views

Is there an exact solution for induced velocity during vortex ring state?

In plots such as these, the section between -2 and 0 has no exact solution. As shown in the first image, the other two formulas are known, but not during vortex ring state because, as seen in the ...
1
vote
1answer
65 views

What are the repercussions of flying an aircraft with an invalid N number on the side?

I have requested a new N number for my airplane a few months ago. Thinking the change would come through I had my airplane painted with the new number. What will happen if I fly it without the number ...
1
vote
0answers
29 views

Is skin friction also pressure drag looking at microscopic level?

Two situation: A) Roughness in boudary layer is taller than height of air which is not moving ,feel oncoming airflow in boudary layer, at front side must be high pressure at rear low pressure etc,so ...
0
votes
0answers
13 views

When do my EASA ATPL exams expire? [duplicate]

so I finished my ATPL exams in July 2019 and started in April 2018 . I just want to know in EASA when do my atpls expire ?
2
votes
2answers
66 views

Why does a jet's combustion energy propel the engine forwards rather than acting equally in all directions to create zero thrust? [duplicate]

I'm a novice. I have high school physics and I've seen many explanations of how a jet engine works. To paraphrase: Fans compress air into a chamber where combustion energy is created, which spews ...
-1
votes
1answer
88 views

In the USA, how much more expensive is 100LL compared to Jet-A1?

I have never flown an aircraft before and do not have any clue of what the fuel prices are. I was doing some research recently and found that some websites say Jet-A1 costs about 1.5 - 2 dollars per ...
0
votes
0answers
48 views

What effect do urban wind conditions have on operating tiltwing aircraft and gyrocopters?

From this research it seems there are quite a lot of strong wind in suburb residential area and around high-rise buildings. High-rise buildings would also create wind tunnel effect and eddy winds. ...
2
votes
0answers
52 views

What is the speed of gas in the core of a jet engine?

Coming from a slightly related question, I want to know what is the speed of the gas in the core of a jet engine, after combustion but before the first turbine stage. I'll just pick a random example: ...
16
votes
3answers
3k views

Why don't flights fly towards their landing approach path sooner?

For example shown here, the flight is heading to the centre of the airport, until it gets close when it then moves into it's landing path. This is an inefficient use of time, fuel and emmissions, why ...
1
vote
0answers
19 views

What is the fan pressure ratio in a turbofan?

What is it and how does it affect efficiency and thrust?
-5
votes
0answers
38 views

747 should have been bought at first [closed]

We all know that at first the 747 failed because supersonic travel was coming up and wanted to save money for the Concorde but the 747 is fast and efficient and affordable so they should accept both ...
0
votes
1answer
208 views

I'd like to know the name of this aircraft

I recognize it but can't recall the name, if anyone can tell me that would be great.
0
votes
1answer
100 views

Why is the air:fuel ratio of a turbojet engine typically around ~1:4 - 1:3 and not around ~1:15 (the stoichiometric ratio)?

Also, what is the maximum fuel:air ratio possible in a combustion chamber of a jet engine?
0
votes
0answers
104 views

Does Betz's Law apply to jet engine turbines?

Betz's Law says the extractable power from wind is only 59% (16/27) of its original power. $$P_{max} = \frac{16}{27} \frac{1}{2} \rho A v^3$$ Rho is the gas density, A is the cross section area of gas ...
10
votes
1answer
387 views

Why did Concorde have a 8000 ft airport elevation limit?

According to the Concorde Flying Manual Volume II(a) - 1 Operating Limitations - page 01.01.02 the take-off and landing airfield altitude is minimum -1000 ft and maximum 8000 ft. Why is Concorde ...
8
votes
3answers
2k views

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

The Canadian Flight Training Manual stated this when talking about maximum endurance: For reciprocating engines, maximum endurance is achieved at sea level. The book does not explain further as to ...
0
votes
1answer
50 views

Pitching Moments CG vs CP vs AC

Probably the question will be a little bit confusing but I'll try my best to make it clear. Due the position of the CP with respect of the AC, symmetrical airfoils don't produce pitching moments, but ...
1
vote
2answers
94 views

Why does part 135 require a maintenance log on board the aircraft, but part 91 does not?

During a dispute within friends, it came to my attention that in 135.65 the maintenance log copies must be present in the aircraft, and that 91.407(b) and 91.417(c) have similar rules, but, meanwhile, ...
0
votes
1answer
16 views

pqr computed from ENU and NED axis, are they the same? [closed]

I derived the rotation matricies from inertial to V1, to V2, to body for ENU, as follows. (x -> pitch axis, y-> roll axis, z-> yaw axis) If I compute p, q, r using the following definitions, ...
0
votes
2answers
146 views

What is an Air-Filed Flight Plan? Are aircraft capable of filing flight plan when in flight?

ICAO Doc 4444 mentions to input AFIL in the departure field of flight plan if it has been filed in the air. What is an Air-Filed flight plan? Can aircraft crew file a flight plan in-flight? If yes ...
1
vote
1answer
70 views

Has anyone tested or flown permeable wings to increase efficiency?

See this article: Aerodynamic Performance Improvements Due to Porosity in Wings at Moderate Re Was wing porosity ever tested/used for real aircraft? source: The aerodynamic efficiency parameter ...
4
votes
1answer
119 views

Why is there an altitude limitation on operating the slats/flaps on the A320?

As per the FCOM limitations chapter there is an altitude limitation of 20000 feet for operating the flaps/slats on the A320? Why this specific altitude?
0
votes
1answer
54 views

Calculation of temperature correction for altimeter

I try to calculate the correction of cold temperature for altimeter , i use for this the equation 24 of the Engineering Sciences Data Unit (ESDU) publication but it give me very high number . if i ...
0
votes
2answers
83 views

How does outflow valve work?

As we know that outflow valve normally closes during climb and cabin altitude also increase but why does outflow valve open if we have selected manual pressurisation and increasing cabin altitude !
4
votes
2answers
105 views

Do mechanical attitude indicators have rotation limits?

Do mechanical attitude indicators have limits to the rotations they can display? Wondering since gyros suffer from gimbal lock when two axes become aligned (e.g., at 90 deg pitch, if you were doing ...
5
votes
1answer
210 views

Why does Boeing 247D have reverse slope windows when they were removed from the D models?

Have a look at this article on a famed example of the 247D, DZ203, the first aircraft to make a completely blind landing. The first image is the aircraft during its flights with the RAF, which places ...
1
vote
1answer
87 views

Do raked wingtips reduce drag of a hang glider?

https://rakedwingtip.wordpress.com/ Do they realy reduce drag or improve performance? If so, how?
3
votes
0answers
49 views

Is there a database of aircraft 3D models that are accurately created [closed]

I was just wondering if there was such a thing as the title describes. I am trying to work on a machine learning algorithm that generates aircraft designs based on what it learns from current designs, ...
0
votes
1answer
35 views

Do Air Passenger Number statistics on a route refer to both directions of flight?

Looking at the air passenger data for specific routes, I was wondering if this data referred to just one direction of the route, or both directions? For example (see link below), Philadelphia's most ...
-3
votes
1answer
136 views

What aircraft has a sustained bright orange light visible at night/early morning?

This morning around 6 a.m. in Durham, N.C. I was sitting on my porch and saw a bright orange light, I thought it was Mars it was so orange, but it was very bright. After looking at it for a moment it ...
0
votes
1answer
40 views

why is rhumb line bearing for this question 270 as the answer?

An aircraft leaves position "G" in lat 40 degree South and flies the following Rhumb Line tracks and distances: ...
2
votes
1answer
80 views

If an aircraft has two altimeters what is the allowed difference between them?

If an Altimeter must be within +/- 75 of known field elevation, and the aircraft has two altimeters, one could be +74 while the other could be -74 and both would be within 75 of known field elevation, ...
1
vote
1answer
76 views

Deicing Rod for Propellers

Similar to a card hitting the spokes of a bicycle, the card is soft enough to knock the dust off the spokes with no damage. What material would be best to impede the propellers to chip off the ice. ...
3
votes
2answers
190 views

Why are the Antonov An-124 horizontal stabilisers directly behind the wings?

With the wings being on the same plane as the horizontal stabilisers, turbulent air from the wings would interfere with the airflow over the elevators making them flutter. Surely putting the ...
0
votes
1answer
145 views

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

Russian/Soviet aircraft design has always intrigued me, and even more so when coming across this photo of the Tupolev Tu-134UBL with its pointy nosecone. Having looked up the performance ...
1
vote
0answers
66 views

How does push forward work? [duplicate]

From Facebook video shows a BA aircraft being pushed forward into a hangar. I wonder how it works? Do they rotate nose wheel 180 degree to push it or there is attachment point for the tug to push ...
1
vote
1answer
89 views

Why does a force on a propeller act 90° “ahead” due to gyroscopic precession?

This is a common explanation: A tailwheel airplane is on the takeoff roll and the tail comes up, the propeller disc rotates forward. That's akin to someone pushing on the top of the disc. The force ...
1
vote
1answer
71 views

What is pendulous suspension in magnetic compass?

I am not able to understand what is pendulous suspension and how centre of gravity and centre of suspension are related in magnets and their errors. Can someone explain this in layman language or ...
13
votes
4answers
3k views

Why are/were there almost no tricycle-gear biplanes?

A friend recently asked me: are there any tricycle-gear biplanes? After hunting around, we found the Waco AVN-8, but that's all. This causes me to ask: is there an aerodynamic or other design ...
0
votes
2answers
77 views

What airspeed is required at sea level to create the same aerodynamic pressure as cruise altitude?

I would like to know what speed would be required, at sea level, to exert the same aerodynamic pressure as experienced at cruise altitude. For example, if an airliner were traveling at 500kn at 35,000'...
1
vote
0answers
63 views

What descent rate would be a “hard” landing in a Huey or similar helicopter with skids?

I would like to know what vertical descent rate a Huey or other helicopter with skids can land safely at. What would be considered a "hard" landing that would require air frame inspection? ...
0
votes
1answer
128 views

Is there an ideal lift distribution for human-powered aircraft?

Is there an obvious, ideal lift distribution for human-powered aircraft? Eliptic or Bell(unloaded tips) distribution? For this who will tell Bell distribution,I have counter question ready,why dont ...
0
votes
1answer
50 views

Impact of centre of gravity position on stall recovery

Can somebody explain what is the impact of CoG position on stall recovery. I heard that stall speed is higher with forward CoG comapared to aft CoG, but does it have influence on stall recovery? Is it ...
8
votes
2answers
2k views

How is it possible for the MIG 21 to have full rudder to the left, but the nose wheel move freely to the right and then straight or to the left?

How is it possible that the MIG 21 has the rudder to the left, but the nose wheel moves freely to the right, and then straight or to the left on the runway? See timestamp 1 min 11 sec in this video:
2
votes
2answers
77 views

What are differences between vortex, swirl, eddies and wake?

These terms seem to have the same meanings. Can anyone differentiate them?
0
votes
1answer
83 views

How to estimate runway length for airport master planning?

I use the manufacturer aiport planning manuals. But they are incomplete (unless for Boeing). Airbus and Embraer for example, only present range X weight charts for MTOW. Is there a free (or affordable)...
8
votes
1answer
880 views

In missiles, what actuators are used for the control surfaces?

In a normal airplane, hydraulics or even cable-pulled systems are used to power the control surfaces. In a missile, that seems infeasible. What device is used to move the control surfaces, and where ...

15 30 50 per page
1
2 3 4 5
403