| What is a black hole ? In simple words, a black hole is a strange astronomical body which is formed when a massive star dies. As the star dies, the nuclear fusion reactions stop because the fuel for these reactions gets burned up. At the same time, the star's gravity pulls material inward and compresses the core. As the core compresses, it heats up and eventually creates a supernova explosion in which the material and radiation blasts out into space. What remains is the highly compressed and extremely massive core. According to the general theory of relativity, a black hole is a region of space from which nothing, including light, can escape. It is the result of the deformation of space-time caused by a very compact mass. In other words, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. Black hole is something which has immense gravity and thus nothing can pass through it. |
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| Why not even light can pass through a black hole? Suppose that you are standing on the surface of the earth. You throw a rock straight up into the air. Assuming you don't throw it too hard, it will rise for a while, but eventually the acceleration due to the planet's gravity will make it start to fall down again. If you threw the rock hard enough, though, you could make it escape the planet's gravity entirely. It would keep on rising forever. The speed with which you need to throw the rock in order that it just barely escapes the planet's gravity is called the "escape velocity". As one would expect, the escape velocity depends on the mass of the planet: if the planet is extremely massive, then its gravity is very strong, and the escape velocity is high. A lighter planet would have a smaller escape velocity. The Earth's escape velocity is 11.2 km per second (about 25000 mph), while the Moon's is only 2.4 km per second (about 5300 mph). Now imagine an object with such an enormous concentration of mass in such a small radius that its escape velocity was greater than the velocity of light. Then, since nothing can go faster than light, nothing can escape the object's gravitational field. Even a beam of light would be pulled back by gravity and would be unable to escape. | |
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Even Horizon and the Singularity of a black hole In general relativity, gravity is a manifestation of the curvature of space-time. Massive objects distort space and time, so that the usual rules of geometry don't apply anymore. Near a black hole, this distortion of space is extremely severe and causes black holes to have some very strange properties. In particular, a black hole has something called an 'event horizon'. This is a spherical surface that marks the boundary of the black hole. You can pass in through the horizon, but you can't get back out. In fact, once you've crossed the horizon, you're doomed to move inexorably closer and closer to the 'singularity' at the centre of the black hole.  You can think of the horizon as the place where the escape velocity equals the velocity of light. Outside of the horizon, the escape velocity is less than the speed of light, so if you fire your rockets hard enough, you can give yourself enough energy to get away. But if you find yourself inside the horizon, then no matter how powerful your rockets are, you can't escape.The horizon has some very strange geometrical properties. Far away from the black hole, the horizon seems to be a static, unmoving spherical surface. But once you get close to the horizon, you realize that it has a very large velocity. In fact, it is moving outward at the speed of light. That explains why it is easy to cross the horizon in the inward direction, but impossible to get back out. Since the horizon is moving out at the speed of light, in order to escape back across it, you would have to travel faster than light which is impossibly practically as well as theoretically. | |
Gravity is a well-known term and everyone in general knows that it is a pulling force. It is such a force which keeps everything in contact and everything thus constrained to something. Gravity of earth keeps the moon where it is supposed to be and gravity keeps you where you are now. If you weren’t under gravity of earth, you would be floating in space. This understanding of gravity is not really limited to the force of attraction between two masses or let’s says a pulling force. It is something more mysterious.
Newton’s Gravity:
Gravitational force = (G * m1 * m2) / (d2)
where G is the gravitational constant, m1 and m2 are the masses of the two objects, and d is the distance between the centres of gravity of the two masses.
Einstein’s Gravity:
Thus, space-time is a common quantity and as time and space are bonded together.
Space is a fibre where our universe exists. This can be seen on the picture below.
Thus, when an object is placed on this fabric space, it distorts the space-time and created a curve on the space-time. This is what we experience: gravity. Big masses create big distortion (big curvatures) while small objects create, small distortion. This is because of this face that the smaller objects are pulled towards bigger objects. Consider this with earth and moon.
Our earth being a big mass has created distortion in space-time and thus a curvature is created on the fabric of space. The moon is thus constrained to move in its orbit and hence attracted towards the earth and so are we all.
A roll motion is an up and down movement of the wings of the aircraft as shown in the picture hereby. This type of motion is used to change the direction of an aircraft during flight. For an aircraft to be rolled, ailerons’ are used at the rear section of the wings. The movement of ailerons cause the aircraft to roll.
A pitch motion is an up or down movement of the nose of the fuselage of the aircraft as shown in the picture hereby. This type of motion is used to change the altitude of an aircraft during flight. For an aircraft to be pitched, elevators are used at the rear section of the horizontal stabilizer. The movement of elevators up or down cause the aircraft to pitch.
A yaw motion is a side to side movement of the nose of an aircraft during flight. This can be seen clearly in the picture below. This type is motion is vital for changing the direction or rotating the aircraft. Rudders located at the vertical stabilizers are used for yawing motions in an aircraft.
An agreement was made previously to deliver an total operational force of 24 aircraft by the end of 2010. The future goal developed by manufacturer is that a total force of 200 bombers will be completed by 2020.
Enjoy some wonderful photographs of this majestic aircraft:
B787-Dreamliner is well-known for its high speed and the use of composite parts in its structural parts. The manufacturer claims to have a maximum speed just below Mach 1 and thus making it to be the fastest commercial aircraft. It has a maximum range of about 15000 kilometres.Several types of models are prepared like 787-3, 787-8 and 787-9. The MTOW of these models are 170,000kg, 228,000kg and 248,000kg respectively.
Along with this, the competition in aircraft manufacturing races between Airbus and Boeing. Just couple years back, Airbus launched A380 which is the largest passenger aircraft with capacity of more than 800 passengers and again Boeing now launched fastest commercial plane. Airbus goes for passenger capacity while Boeing targeted speed performance as the race for benchmark continues.
Quantum: Quantum is the minimal unit of any kind of physical entity. In simple words, it is the smallest quantity that can be thought of. For example: Photon is the smallest element of light, thus photon is the light quantum.
One another example that I can think of is the digital technology that we use intensely. We have now microprocessor, transistors and so on. But the basis of all these things starts with the concept of bits and bytes. Similarly, the physical world that we pass around is also composed of bits. These infinitesimal objects are the quanta. Everything is made up of small bits called quantum.
(Note: one quantum, two quanta)
Quantum modelling was started by famous German physicist Max Plank in 1900 which then was followed by Albert Einstein and the field is still flourishing till the date. The breakfast era of Quantum Mechanics includes names like Pauli, Heisenberg, Schrödinger, Born, Rutherford and Bohr. Eventually we are in a new era and by now we have better understanding of the quantum and the way universe works.
Believing the unbelievable: The world of quanta or the world of small is different to the world that we face. It is thus a vague part of physics to come across quantum mechanics. One has to reformat himself and the way he thinks. The system of logic works in a different way in a quantum world. The other thing one should not be confused is that the quantum world works differently compared to our world although they are the fundamentals of our world. As an example, steam is hot while ice is cold in our living world. On the other hand, the quantum world defines that they are composed of similar quanta and hence they have similar properties. Such logics make the world of quanta very different to our world.Applications of Quantum Mechanics:-
Planck's constant is very important to quantum theory and quantum mechanics in general. It states that the energy of each quantum is equal to the frequency of the radiation multiplied by the universal constant: E=f*h, where h is 6.63 * 10E-34 Js.
Quantum mechanics can be referred to as the mathematical description of physical reality of the matter, like almost any other scientific model. According to quantum mechanics the most complete description we can make of a system is its wavefunction, which is mathematically speaking just a number varying between time and place.
Quantum theory can provide accurate descriptions for phenomenons such as black body radiation and the stability of electron orbitals.
The famous quantum theory of the atom was primarily developed as an explanation for the electron's staying in its orbital, which couldn't at that time be explained by Newton's laws of motion.
Quantum particles have one very unique property, namely they can be in different states at the same time. This is referred to as the "superposition" of two conditions. Based on this for instance the 'spin' of an electron can be pointing in two different directions at once.
Many scientists believe that super-fast quantum computer are only matter of time.
Quantum computers have also unlimited potential and they are likely able to fix problems that would normally take millions of years to solve, much faster than ordinary computers. Currently the biggest problem with development of quantum computers is that scientists can only hold a limited number of atoms in place for a very short period of time.
Quantum mechanics allows a quantum computer built on these principles (still theoretical, to perform tasks that are currently thought impossible to do efficiently on a normal computer, for instance breaking with ease all currently possible encryption standards.
Quantum mechanics plays key role for understanding how individual atoms combine covalently to form chemicals or molecules, and is so well used in chemistry that is even known under the name of quantum chemistry.
Quantum mechanics has had significant impact on today's modern technology such as lasers, transistors and diodes.
Nepal’s national carrier, Nepal Airlines Corporation (NAC) is modernising its international fleet with one A330-200 wide-body and one Airbus A320 single aisle aircraft. The new Airbus aircraft will be deployed on international services to Japan and will start connecting Nepal to Europe with direct flights.
The Memorandum of Understanding (MoU) was formalised at the Dubai air show.
The two class, A330-200 will be deployed on routes to Europe and North Asia and will play an instrumental role in developing Nepal’s tourism industry especially around to country’s ‘Visit Nepal 2011’ tourism campaign to attract foreign tourists. The dual class A320, will be deployed on regional routes and operate as far as the Middle East as well as in South East Asia.
Nepal Airlines Corporation (NAC) was incorporated on 1 July 1958 through enactment of Nepal Airlines Corporation Act. 2019. The Airline currently flies to 10 international destinations and 30 spectacular domestic locations in the heart of the Himalayas.
Nepal oficials seem happy with the MoM of these new airliners, but it is to see in the coming days whether these aircraft will boost their fleet or will these aircraft have similar condition as to those of the previous Boeings'.
Sources: Airbus, Nepal Airlines Corporation, NepalNews, Kantipur
The civil aviation service started in Nepal in 1953 with three old American -made DC-3 Dakotas belonging to an Indian company. After five years, Nepal established its own registered airline, Royal Nepal Airlines Corporation in July 1958 with one DC-3. At the beginning,its service was limited to Indian cities like Patna, Calcutta and Delhi in the International Sector and to Simara, Pokhara and Biratnagar in the Domestic Sector. 
By the early 1970s the airline had introduced Hawker Siddeley HS-748 turboprops, and Boeing 727 jet airliners were introduced in 1972 after Kathmandu's runway had been extended for medium sized jet operations. The Boeing 727s were gradually replaced by Boeing 757s.It is powered by four 11,000-shp turboprop engines and has a MTOW of 141,000 kg. It can cruise at 780 km/h (480 mph; 420 kn) (Mach 0.68 - 0.72) and has flying range of about 3300 kilometers.
It has been built in colabration of eight different European nations. The partner nations, France, Germany, Italy, Spain, the United Kingdom, Turkey, Belgium, and Luxembourg, signed an agreement in May 2003 to buy 212 aircraft. Besides that, Malaysia and South Africa are also associated with this production.
More to come ...
Venue: Wind swept sand dunes of Kill Devil Hills, 4 miles south of Kitty hawk, North Carolina, United States of America
Time: about 10.35 AM (Thursday), December the 17th of 1903 AD
Characters: Heroes - Orville and Wilbur Wright (brothers) Other characters include 5 local witnesses.
What happenned? : Wright brothers achieved the milestone with successful flight of Wright FlyerI.
Lets leave this moment of 1903 and get back to our topic. You may think that this is a bit weird that I am telling you to get back to our topic as I am already talking about aeronautical engineers who got first flight and amazed the world.
I have a question for you, when did man started thinking of flying? Were the Wright brothers the first to think about flying in the sky. Actually, they were motivated from other early aeronautic engineers in the field. We have ancient stories; Greek myth of Daedalus and his son Icarus who flied in the sky and went near the sun and finally died unfortunately because the wings made of wax liquidified. This shows that man had interest in flying from very ancient ages.
Again returning to today and loking at the present world, this is 21st century and it is of no amaze that the humans also can fly in the sky. This has been possible with the invention of aircraft and the dramatic developments in aviation technology. The compliment for this achievement goes not only to a single person in the aviation history but there are many persons linked to the development beginning from Aristotle to the scientists and engineers of the present world. Without this deveopment, it wouldn’t have been possible to go around the space or to land on the moon or to discover planets and satellites. Just after a century of its successful invention, aeroplanes have been most important means of transportation and now even the far trips around the world are possible in just a day by means of planes.
Ornithopters: Various ancient and medieval people fashioned wings and met with sometimes disastrous and unsuccessful consequences leping from towers or roofs, flapping vigrously. The concept of flapping wings on arms failed and was replaced by various mechanical mechanisms, powered by some type of human arm or leg or body movements. Such machines are called ornithopters.
Montgolfier: Montgolfier is well-known for his hot air ballon. On Novemebr 21, 1783, Montgolfier hot air ballon lifted from the pround near Paris which can be taken as the first aerial voyage on history.
Sir George Cayley (1773-1857): "The True Inventor of the Airplane". In 1799, he engraved on a silver disk the concepts of a fuselage, a fixed wing and horizontal and vertical tails. He is the first person to propose separate mechanism for the generation of lift and propulsion. He was teh first one to define the shape of aircraft as fuslage, fixed wings and tails. He is called as the grandfather of the concept of the modern airplane.
William Samuel Henson (1812-1888): He was a contemporary of Caley. In April 1843, he published a design for a fixed wing airplane powered by a steam engine driving two propellers, called as the aerial steam carriage.
John Stringfellow: He was a friend of Hension and made several efforts to bring Henson's design to fruition. He built several small steam engines and attempted to power some model monoplanes off the ground. He was close but unsuccessful. However, his most recognized work appeared in the form of a steam-powered triplane. Although it was unsuccessful too, but again it was influential and carried publicity.
Felix du Temple: Du Temples' airplane is called the first powered airplane although it was not completely successful. It was teh first powered airplane which hopped off the ground but for only hops. In 1857/58, French engineer Temple flew the first successful powered model airplane in history. It was a monoplane with forward wept wings and was powered by clockwork but it was then assisted takeoff. It is thus noit a truly controlled, sustained flight in history.
Mozhaiski : Alexender F. Mozhaiski designed a aircraft in 1884 which was a steam powered monoplane. His design was a direct descendant from Henson's aerial steam carriage. With I>N Golber as pilot, this plane was launched down a ski ramp and flew for a few seconds. As with Du Temple airplane, no sustained flight was achieved.
Otto Lilienthal (1848-1896) : This is a huge name in the history and is known as the gliderman in the history of aviation. He earns the credit of first fully successful gliders in history. During the period from 1891 to 1896, he achieved more than 2000 successful glider flights. He developed a new flying philisophy and obtained many aerinautical data. If he had not been unexpectedly killed in a glider crash in 1896, Lilienthal might have achived powered sustained flight before the Wright brothers. Actually, he was the one from whom Wright Brothers were interested in flyers.
Percy Pilcher (1867-1899): He is the extender of the glider tradition. He followed the traditon of gliding with Lilienthal. He was a Scot engineer, enthousiastic towards Lilienthal's work . He made several glides from artificial hills. In 1897, he calculated that an engine of 4hp weighting no more than 40lb, driving a 5 feet diameter propeller would be necessary to power his plane Hawk off the ground. Thus, he spent 1898 designing and constructing such an engine. It was completed and bench-tested by the middle of 1899. Then, it was a bad day for him as his work couldnt kiss success when he was killed while demonstrating his Hawk glider. The weather was bad and on his first flight, the glider was throughly water soaked. On his second flight, the heavily soked tail assembly collapdes and Pilcher crashed to the ground. It was a great loss to aeronautics that missed Pilcher at the age of 33. Had he not been dead, he would have achieved a lot lot successes.
INTRODUCTION OF AERONAUTICS IN AMERICA: America was busy consolidating a new government and expand its frontiers. There was thus not much interest or time for serious aeronautical endeavours. But once the wave came to America, the solution of flying came which in Europe was just hanging. Thereafter, as the success was achieved in America, there was a lot of development in Europe than that in America. So, the base was created in Europe and the achievement was made in America. After that, the flourishment and dramatic development was seen in Europe. The credit od beginning of aeronautical research goes to Octave Chaunte.
Octave Chaunte (1832-1910) : He was a French born American and a resident of Chicago. He became interested in mechanical flight in the 70s of 19th century only. He published books and assimilated several aeronautical informations he could find. His major specific contricution to the aviation was teh successful biplane glider which introduced the effective Pratt truss method of structural rigging. The Wright Brothers were directly influenced by the biplane glider, and in this sense Chaunte provided the natural bridge between Stringfellow's triplane (1868) and the first successful powered flight(1903).
Samuel Pierpint Langley (1834-1906): Langley, secretary of the Smithsonian institution, achieved the first sustained - heavier than air unmanned powered flight with his first scale AERODOME in 1896. However, his attempts at manned flight are unsuccessful, the last one failing on December 8th, 1903 - just 9 days before the Wright Brothers stunning success. His AERODOMES were tanden-winged vehicles, powered by a 1-hp steam engine of Langleys own design. He was influenced by John Stringfellow's small aerosteam engines.
Wilbur Wright(1867-1912) and Orville Wright (1871-1948): Wright brothers are the inventors of the first practical real airplane which was manned, and powered plane which flew for more than a minute from the ground and sustained to a height. One of tje greatest day in aeronautics history, indeed in the history of humanity and technology, is December 17, 1903. Their successful flight revolutionized life during the 20th century.
* The development of aeronautics takes off exponentially after the Wright Brothers public demonstrations in Europe and the United States in 1908. The ongoing work of Glenn Curtiss and the Wrights and the continued influence of Langley's early work form an important triangle in the development of aeronautics before World War I. The hard competition between Wrights and Curtis can be seen as an important phase in the development of aeronautics. Curtis is also one of the greatest aerinautical engineer in teh post-1st plane era working and developing designs of airplanes. He designed many faster and effecient planes.
The faster and higher challenge in aeronautics was the work for the aeronautical engineers around and after World Wars I and II. In fact, the world wars contributed to the development of aviation too when the whole world was attenting to make est aircraft and the fighter planes. Before world war I, the problem of propulsion was the one fot aircraft. Coming now, there are much powerful engines which can propel a huge jet and even spacecrafts. Today, the maximum speed of flight has been pushed to the extreme values of 36,000 ft/sec , which is the escape velocity from the earth by Apollo linar spacecraft. And the maximum height to fly has been achieved in 1969 when man landed on moon. It is just to see what will happen in the future !
Summary : In brief, the following names are the most important names in the history of aeronautics.
- Sir George Cayley
- John Stringfellow
- Otto Lilienthal
- Samuel P. Langley
- Wright Brothers
- Glenn Curtiss
This was a short history about the development in aviation technology. In the coming posts, I will write more about Airfoils, Wings and othere aerodynamic shapes and discuss how an aircraft gains lift and what are the effects of drag.
