Herbig–Haro (HH) objects are small patches of nebulosity associated with newly born stars, and are formed when narrow jets of partially ionized gas ejected by those stars collide with nearby clouds of gas and dust at speeds of several hundred kilometres per second. Herbig–Haro objects are ubiquitous in star-forming regions, and several are often seen around a single star, aligned with its rotational axis.
HH objects are transient phenomena that last less than a few thousand years. They can evolve visibly over quite short astronomical timescales as they move rapidly away from their parent star into the gas clouds of interstellar space (the interstellar medium or ISM). Hubble Space Telescope observations have revealed the complex evolution of HH objects over the period of a few years, as parts of the nebula fade while others brighten as they collide with clumpy material of the interstellar medium.
When you are in the combat zone, agility of a fighter jet is of utmost importance. But as an engineer, if you have already fiddled around with the wing structure your next option would be to fiddle around with the direction of the thrust.
Thrust vectoring is primarily used for directional control in rockets and jets. And one achieves this by manipulating the direction of thrust .
This generates the necessary moments (and forces) that enable the directional control of the aircraft.
An aircraft traditionally has three “degrees of freedom” in aerodynamic
maneuverability; pitch, yaw and roll. **
The number of “dimensions” of
thrust vectoring relates directly to how many degrees of freedom can be
manipulated using only the vectored engine thrust.
vectoring allows control over two degrees of freedom (typically pitch
plus either roll or yaw) while 3D controls all three.
Lockheed Martin F35B
The F-35B short takeoff/vertical landing (STOVL) variant is the world’s first supersonic STOVL stealth aircraft.
It achieves STOVL by swiveling its engine 90 degrees and directing its thrust downward during take off/lvertical landing mode.
In the following gif you can witness the transition from a 90 degree tilted engine towards a forward thrust engine during flying.
Unlike other variants of the Lockheed Martin F-35 the F-35B has no landing hook. And as a result, witnessing its landing is rather pretty special.
But nevertheless, this is one of those posts which addresses a topic that has been a gold mine for research. If this sort of thing fascinated you, there have been a lot of research conducted by NASA do check them out.
Fires in large, open spaces like aircraft hangers can be difficult to fight with conventional methods, so many industrial spaces use foam-based fire suppression systems. These animations show such a system being tested at NASA Armstrong Research Center. When jet fuel ignites, foam and water are pumped in from above, quickly generating a spreading foam that floats on the liquid fuel and separates it from the flames. Since the foam-covered liquid fuel cannot evaporate to generate flammable vapors, this puts out the fire.
The shape of the falling foam is pretty fascinating, too. Notice the increasing waviness along the foam jet as it falls. Like water from your faucet, the foam jet is starting to break up as disturbances in its shape grow larger and larger. For the most part, though, the flow rate is high enough that the jet reaches the floor before it completely breaks up. (Image credit: NASA Armstrong, source)