Federico
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  • Member for 7 years, 10 months
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How is thrust generated by a propeller?
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15 votes

It's the same thing, it changes only the point of view, see Newton's third law: for each action there is an equal and opposite reaction, i.e. to create thrust, the engine has to push air backwards. ...

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Why 1st and 2nd class but not fast or slow airplanes?
15 votes

The optimal speed of the aircraft is set by the manufacturer. isn't the cost directly proportional to speed? No, any speed above or below the optimal one will lead to sub-optimal performance of ...

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What programming languages are used for equipment onboard aircraft?
15 votes

As far as I know, there is no directive on which language to use. You have guidelines on how to test and certify software, but as far as these guidelines are concerned, no language is preferred, it is ...

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Do jet fighters have air conditioning systems?
14 votes

From second-hand experience (I can say I am really close with a Tornado pilot), the Tornado has a compressor stage airbleed that directs some cold air directly in the cockpit. He would describe it as ...

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What is the distance from an airport from which an airliner climbs above 550 m?
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14 votes

For the landing is quite easy. Airliners usually approach an airport descending along $3^\circ$ slopes. This means that they will be 300m AGL approximately 5.7km before the runway threshold, and they ...

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Why did this commercial flight fly in circles while far from the destination?
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14 votes

The first "circle" is a holding pattern. We discussed those here. In particular, it seems that you were on hold at VINIL or VEPLI, according to the approach charts (page 5 of the PDF). The second one ...

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What is this on top of the Air Force One?
14 votes

That is not simply an E4, but a "B" variant. The hump houses a SHF antenna. (Source) December 1979 a fourth aircraft (75-0125) was added. This aircraft was fitted with the distinctive “Hump” on the ...

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Why are the power and drag curves called polars?
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14 votes

It is an historical name. The first polars were drawn by Otto Lilienthal in polar coordinates. Here (sorry, German link) we find an example:

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What kind of delay does the A320's fly-by-wire system add?
13 votes

I don't have an answer for the timings (I personally don't think that's publicly available information), but I can answer this is the delay noticeable by pilots? as I have some direct experience, ...

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How can an aircraft turn if the horizontal force component is zero?
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13 votes

The problem of the picture you are looking at is that both the actual and the apparent forces are shown. The real force is the centripetal one (that in turn is only the horizontal component of the ...

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Why is the fuselage on an airliner circular-shaped?
13 votes

Drag has little to nothing to do with it. The primary reason why the fuselage is circular (or elliptical) shaped is that the cabin is pressurised. This means that, mostly during cruise, the interior ...

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Could turbine or compressor stages of a jet engine be switched off to improve fuel efficiency?
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13 votes

You cannot "switch off" a stage of a turbine engine. As seen elsewhere jet engines are a single block mechanically locked together: all the stages (compressor AND turbine) connected to the same shaft....

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What are the data elements shown on the GE235 flight data recorder (FDR) plot?
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13 votes

From top to bottom: main gear : whether there is weight-on-wheel not [scale on the left, in blue: "air/gnd"] (thanks to DeltaLima for pointing this out) VHF1 : probably if there was ...

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How to plot the pressure distribution over an airfoil?
13 votes

I have found only the description of this pattern with experimental graphs. That's because that is the best way to have detailed and precise data: you either simulate (e.g., with Nastran-Patran or ...

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Why is managing CG (centre of gravity) important?
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13 votes

Why do people have to worry about CG? Because the manufacturer has designed the aircraft following certain criteria, and one of those is where the CG will be during flight. If the CG is outside that ...

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What is this aircraft, when was it produced and used and what was its role?
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12 votes

It is a Tu-128. In particular it seems to be the "UT" (training) variant: Image source Full-scale production of the aircraft began in 1966, with 188 Tu-128s built to 1970, that total apparently ...

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Can a super land without flaps/spoilers?
12 votes

Any aircraft can land without those devices. I would say that the Gimli Glider is a nice example, with no power it could not extend its flaps/slats. They are used, as @ratchetfreak notes in the ...

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What is the visual difference between turbine fans and compressor fans?
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12 votes

Assuming we are speaking of axial compressors/turbines Compressor blades are generally thin and straight, and resemble a tiny rectangular wing with low camber thickness. Image source Turbine blades ...

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Given the same engine, why install a gearbox on a turboprop but not on a turbofan?
12 votes

There it says "optimum rotational speed". Is that the speed of the compressor? The speed of the fan? Both. Each has its own optimal speed (that is not the same) and the gear allows them to work at ...

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What is the longest distance at which an aircraft can be visually identified?
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12 votes

The key piece of information here is the "Angular Resolution" of the naked eye. Is called in this way because the key parameter is the perceived angle between two points when looking at them. Let's ...

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Is there any U.S. / FAA regulation that could apply for aviation software?
12 votes

For simulators you have Part 60 of CFR 14 For airborne software the FAA has published AC 20-115, but the main document that refers to is the FAA/EASA RTCA DO-178/ED-12 currently at the "C" version: ...

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Is it possible to hack an airplane while it's moving (in general)?
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11 votes

The answer to Is it possible to hack an airplane while it's moving? is "theoretically yes, movement has no effect on a plane hackability". How can someone "touch" a moving airplane, have the ...

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How did the gyro gunsights of WW2 get the range and lead of a target?
11 votes

I don't understand how it computed range/position to the target and then calculated how much lead is needed. Reading the Wikipedia article you linked, it didn't, but both assertions are unsourced. ...

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Why can't I build an entire jet engine out of carbon fiber?
11 votes

What is relevant is not the melting point, but the temperature at which the material loses its mechanical properties (such as stiffness or elasticity). The epoxy (the material keeping together the ...

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How do paper airplanes create lift if their wings are flat?
11 votes

How does a flat wing generate any lift if both sides have the same air pressure? The two sides do not have the same pressure. A flat plane can still produce lift (think of putting a plate out of the ...

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Why don't big airliners have bigger doors?
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11 votes

Multi-aisle commercial aircraft adopt a multi-door boarding strategy rather than a single-huge door (see the A380 or the B747, both use two doors). This helps under the structural viewpoint: the ...

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Can I derive the wind speed and direction?
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10 votes

No, you need the True AirSpeed (TAS). The Indicated AirSpeed is not a realiable measure of it, since it is not even calibrated against the instrument mounting position and is not intended to measure ...

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Why then don't aircraft fly even higher, for even greater efficiency?
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10 votes

Please meet the ceiling altitude. Above this altitude the aircraft cannot fly fast enough to generate enough lift to stay aloft. This is affected by: weight (more weight needs more lift) engine ...

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Why does the A350-900 call out to retard at 20 feet above the runway?
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10 votes

Why is it like this and not like normally at 0 feet? Normally is not 0 feet: all Airbus (maybe with the exception of the A380, that might have a longer flare) have a "Retard" call at 20ft, not at 0ft....

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Why does Boeing 737 use 2 Inertial Reference Systems (IRS) and GPS?
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10 votes

Could somebody explain a little bit why they need 2 separate GPS and 2 separate IRS? So that if one fails, the other can still be used to complete the flight. Airbus even have 3. What is meant by ...

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