66

It's called 'toe-in' and it's done basically to match the local airflow which is slightly divergent (heading outboard along the underside of the wing). If the engines were mounted exactly parallel to the fuselage, they would be moving slightly obliquely through the local airflow and therefore incurring extra unnecessary drag. Another view of a 777 showing ...


53

Testbed Aircraft Cameos As a young engineer in the 1960s at Pratt & Whitney Aircraft (now UTC’s Pratt & Whitney) in East Hartford, Connecticut, I was involved (along with many others) in the development of their 44,000 pound thrust (lbt) JT9D turbojet, which powered the first Boeing 747 jumbo jet aircraft[ Display footnote number: 2 ]. ...


42

Yes, large turbofans can be turned by hand without too much force. On smaller aircraft this is regularly done as part of the preflight walkaround. You can see an example in this YouTube video of an A320 walkaround: Admittedly, the pilot turns the engine with four fingers here, but you can see that not much force is required. Turning it with a single finger ...


38

Because manufacturing processes are not perfect, and the minute differences between parts as-designed and as-produced are amplified by the high rotational speeds and large diameters of modern jet engines. Take a following back-of-the-envelope calculation: disregard incoming airflow velocity and assume a hypothetical fan with a 1 meter diameter rotates at ...


35

This type of structure is called isogrid structure. Solid walls are usually very heavy and therefore engineers use more weight-efficient structures such as sandwich structures or stiffened structures with stringers and frames. A downside is the huge manufacturing cost compared to other options. As you can see from NASA Report CR-124075 "Isogrid Design ...


33

It appears to be a Rolls Royce Viper turbo jet engine made in 1966. The maker's mark (BSB) derives from Bristol Siddeley, formed from Armstrong Siddeley (the company that originally developed the engine) and Bristol Aero-engines. Bristol Siddeley were later taken over by Rolls Royce. Source: Wikipedia


28

No, Microsoft's image is not doctored. It looks very much like the image from a 2010 press release for the A320 NEO. (Dictionaries say that doctored means deliberately altered or manipulated, in the same sense as the original question's "artificially modified". That would apply equally well to developed photographic film, a software rendering, or ...


28

It looks OK to me: Your confusion may come from the fact that your eyes are focusing too much on the engines themselves both of which are not directly attached to the plane but just hang under the plane. If instead of the engines you look at the pylons you will see that they attach at roughly equal distance on both wings.


27

This is simply a way to achieve required rigidity/strength and vibration dampening with less material than in a solid, even thickness design. Varying the weave pattern gives a relatively easy and a very efficient way to model and produce varying properties to different sections, without having to change the "base" structure thickness. Successfully ...


26

Turning the engine with one finger is not necessarily recommended, because the leading edges of the fan blades are quite sharp. But it is possible. For some experimental vibration measurements, it is preferable to keep the rotors turning slowly to avoid the bearings "sticking" in one position and confusing the results. A common way to do this is ...


26

What you saw is the thrust reverser of the engine, which redirects some of the airflow forwards and therefore helps slowing the aircraft down. The grid like structure are the cascade vanes. This is what it looks like inside the engine: (Airbus A380 FCOM - Engines - Thrust Reverser System) The blue arrows indicate the flow of the so called bypass air, which ...


26

That's nothing special. Car ignition coils also put out 40kV (try grabbing a spark plug wire on your car, that is leaking spark due to insulation breakdown, with your hand while it's running; FUN FUN FUN!). You need that voltage to jump an air gap reliably in a piston, or jet engine's, combustion chamber. That high a voltage allows fairly large air gaps ...


24

The forward location has two benefits: Wing upwash is smaller, so the flow direction at the intake varies less with speed and altitude. This makes the intake more efficient and requires less robustness in its layout. The forward location shifts the wing's center of gravity forward and gives it better flutter damping. How that works is explained here. Wing ...


24

The position of the engine in the model seems correct, what's wrong is the shadow rendering, causing an optical deception. What appears to be the shadow of the engine against the fuselage (making it look very close) is actually the shadow of the wing, lighted from above. The shadow problem is exacerbated by the inconsistent direction of lighting. The sun in ...


22

The plane in the pictures is Boeing JB-52E -test plane. It used to test for instance the General Electric TF-39 engines for the C-5 Galaxy as it was under development


21

These are the auxiliary air inlets for the ECS (Environmental Control System): (image source) They provide air to the primary heat exchanger (A18), which is then exhausted via the ram air exhaust (A20, the tubes visible behind the inlets in your picture).


14

Flaps steepen the descent angle - in other words, you run the risk of falling short of the runway. So in a glide you keep the flaps up until you can be certain of making the landing point. Once the landing is guaranteed, you can then deploy gear as well as flap to slow down as much as possible - being aware that these actions will further reduce the gliding ...


13

It's the reverse thrust door opening. I will get back to you with a picture. Courtesy By Pieter van Marion from Netherlands - PH-BVC KLM, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=29588152 For a brief explanation, once the aircraft has touched down (and in some cases even before it touches down) there are a set of doors and vanes which ...


12

There are advantages in the blades not being "perfectly identical". If all the vibration frequencies were exactly the same, when the blades were assembled to make the complete fan the vibrations would be coupled together and the blades could resonate with a large amplitude, causing increased noise and potentially reducing the life of the blades because of ...


11

Taking into account your wish to ignore all things that make electric aircraft unviable, like power-to-weight ratio of engines and battery capacity, the answer is yes. You would, however, need to compensate the missing jet engine thrust by increasing the fan thrust. Otherwise the answer is no.


9

That would be up to the discretion of the flight crew, what forced landing site they selected, approach route, etc. Typically deployment of flaps in a forced landing scenario will only be done once the airplane is guaranteed to make the landing site by gliding in that landing configuration.


9

This depended strongly on the flight altitude. Staying at low level for the full mission meant that the Me-262 would run out of fuel within 40 to 50 minutes. Climbing above 6 km (20,000 ft) would extend that time to 90 minutes. Time to climb to 9 km was 13.2 minutes, so that would leave a time for engaging the enemy of 60 minutes. Considering that typical ...


9

In general, air acts as an electrical insulator. That is, electricity won't pass through air at normal voltages. Which is good because otherwise you'd have a constant arc to ground through the air from any exposed hot conductor and that would cause lots of problems. As with any insulator, air has a dielectric strength, measured in volts per unit distance. ...


8

Almost all jet engines will have one or more "resonance" conditions where the combination of turbine RPM, mechanical elasticity and aeroelasticity constructively reinforces to cause mechanical or aerodynamic vibration. Think of it this way: If you have a slinky spring (mechanically elastic) toy you can hold it by one end and let the rest drop ...


7

These are certainly targets for an optical CMM (coordinate measuring machine) using laser, structured light or stereoscopy. The targets help define common points on the model from one scan to the next. @mins linked a perfect example of this in his comment below, from which this image is taken. When doing 3D scanning, you want the dots in a random pattern as ...


7

The perspective of the photo, or actually rendering, has been altered perhaps to gain a more dynamic composition. This can be verified by looking at the nose of the plane: it seems flattened sideways, much like the nose of Boeing 737 family has. The A320 family's nose is not oval, but cirular in cross section, just a tad flattened on the top to accomondate ...


6

The airplanes in the photo are quite far apart, at least 1-2 lengths between each (it's just the long lens making them look cheek by jowl), and while in line going straight, they are only using a little over idle thrust to get rolling when required, so the jet blast effects are negligible. The main factor is FOD (foreign object damage) kicked up, and at ...


6

12 point flange cap bolt/screw. For high torque applications, less likely to be accidentally rounded-off. http://www.fbabolt.com.au/12-point-advantages.html


6

What you are describing is a characteristic of fluid dynamics known as eddies. As different portions of the fluid flow faster than others, the friction and surface adhesion between the two layers cause swirling of the fluid and reversal of the current, creating a turbulent flow region. It is this same principle that holds a ping pong ball stationary in a ...


6

All three engines you show are for fighter jets flying at supersonic speeds. These engines need a low bypass ratio: Why do military turbofan engines use a low bypass ratio? To achieve more thrust at lower bypass ratios, the bypass air needs to be accelerated more, which requires more than one fan stage because axial compressors can only add a limited ...


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