Is it possible to use nuclear propulsion to reach 10-15 percent the speed of light?

 To accelerate a standard chemical rocket to 15 percent the speed of light, you would need an amount of fuel exceeding the mass of the observable universe.

Yet in the 1970s, a group of British scientists and engineers designed a spacecraft intended to reach Barnard's Star, 5.9 light-years away, within a single human lifetime. To make the interstellar math work, they had to design a theoretical engine capable of reaching exactly 12 percent the speed of light using nuclear fusion.

Reaching 10 to 15 percent the speed of light—roughly 30,000 to 45,000 kilometers per second—is completely impossible with standard chemical rockets. Nuclear propulsion is the only understood physical mechanism capable of crossing this threshold without relying on highly theoretical concepts like large-scale antimatter production.

However, not all nuclear propulsion is created equal:

• Nuclear Thermal Fission: Standard nuclear rockets use a fission reactor to heat a propellant like liquid hydrogen. They are highly efficient for moving around the solar system but max out far below 1 percent of light speed.
• Fission Pulse Propulsion: The Cold War-era Project Orion proposed dropping small nuclear bombs behind a pusher plate to ride the shockwaves. While a massive leap in power, theoretical models suggest standard fission pulse propulsion tops out at around 3 to 5 percent the speed of light. Beyond that speed, the sheer mass of the required nuclear bombs makes the ship too heavy to accelerate further.
• Nuclear Fusion: To hit the 10 to 15 percent mark, aerospace engineers look to nuclear fusion. The British Interplanetary Society's Project Daedalus proposed an inertial confinement fusion engine. The design involved injecting pellets of deuterium and helium-3 into a reaction chamber and compressing them with powerful electron beams. The resulting fusion explosions, occurring 250 times per second, would be directed out the back by a massive magnetic nozzle.

Because fusion reactions convert a much larger fraction of their mass directly into kinetic energy compared to fission, the exhaust velocity of a fusion drive is extraordinarily high. This makes the 10 to 15 percent target physically possible.

The primary barriers are engineering and economics, rather than the strict laws of physics. A Daedalus-style probe would weigh approximately 54,000 tons, with 50,000 tons of that being fusion fuel. Gathering the necessary helium-3 would likely require deploying floating atmospheric refineries on gas giants like Jupiter. While currently out of reach, a ship powered by a continuous stream of miniature star-like explosions remains the most credible way to eventually cross the interstellar void.

What is the maximum speed of modern commercial airliners?

 Today the fastest commercial jet, the Global 8000 can fly at Mach 0,94 , that's approximately 626 Knots TAS (1160 kph). With a hefty tailwind you can even go some 150+ knots (270 kph) faster over the ground. The modern commercial long distance aircraft are designed for best cruise at Mach 0.85 at roughly 35,000 feet MSL.

The maximum cruise is around Mach 0.90 at similar altitudes. The maximum cruise is limited due to selected airflows going transonic around the airfoil surfaces and causing increased drag.

Most large jet powered aircraft are limited to around .98 Mach since none are designed or built (or permitted) to exceed the speed of sound. The actual speed in knots or mph's varies with atmospheric conditions so a Mach limit is usually controlling.

The actual speed varies with altitude (faster as you get higher into less dense air) but generally, around Mach .92 to .95. At this high speed, the fuel consumption goes up dramatically so most airlines limit their speeds to around M .78 to M .85 or thereabouts, depending. As the upper surface of the wing and other surfaces approach the high end of the speed spectrum, the drag coefficient goes up and even in the transonic range, fuel consumption becomes an issue.

The speed at which a passenger jet can fly is limited by the faster air on the upper side of the wing which must at all costs be less than the speed of sound, or otherwise very dangerous phenomenons WILL take place. Normally the center of lift on a wing is at about 1/3 of the wing cord, but as you transit into sonic speed this center of lift will move aft, and as anyone can understand this will induce a pitch-down moment on the airplane.

Now that the Concorde is out of service there are no supersonic civilian aircraft. All remaining large commercial airliners and even regional jets can operate in the high subsonic range (>0.75 mach) at high altitudes.

At what speed do planes usually take off?

 Boeing 737 usually takes off right around 150 MPH. It's also interesting that the acceleration rate is actually quite slow. It picks up speed more gradually than you'd think. Takeoff speeds vary tremendously from one aircraft to the next, and also can change for the same aircraft from one flight to the next based on such factors as the density altitude and the aircraft's weight.

Takeoff speed is determined by a number of factors including the specific type of aircraft, how heavily the aircraft is loaded, flap settings, length of the runway, and altitude of the takeoff airport. The weather can also have an impact as pilots may wish to take off at a higher speed in case of a sudden change of wind direction and resulting tailwind.

For smaller regional jets, takeoff is in the range of 115 to 130 knots. For aircraft such as Boeing 737 and Airbus A320 family, takeoff is in the range of 130 to 150 knots. For mid-size aircraft such as Airbus A330 and Boeing 757/767/777/787, takeoff is in the range of 140 to 165 knots. For larger double deckers such as Boeing 747 and Airbus A380, takeoff is in the range of 145 to 175 knots. Just as a sidenote, Concorde took off at around 200 knots with no flaps when fully loaded.

Most of the time, commercial aircraft with passengers on them will take off around 5 to 10 knots faster than the absolute lower limit for that configuration. This is just to allow the pilot to correct an excessive pitch up or incorrect power setting before it results in a classic departure stall. Takeoffs are broken down into several different speeds called V1, Vr, and V2. V1 is known as the decision speed because this is the speed at which you must commit to takeoff because there isn't enough runway to stop in time. Vr is the rotation speed and is the speed at which the pilot should begin to pull up off the runway. V2 is the safe takeoff speed, and once in the air V2 is the speed that means if an engine failure is suffered the aircraft can continue to climb.

Weight alone has little to do with takeoff speed. The design of the wing doing the lifting is much more important. That's why both an Airbus A340 and a Boeing 747 weighing half again as much take off at about 155 knots under normal conditions from a near-sea level airport.

How does an aircraft reduce its speed for landing?

 Drag is what slows an airplane in the air. One thing that surprises many people is that when you reduce engine power, you don't actually slow down. Instead, when you pull the throttles back, the plane descends, but at basically the same speed. The real way to slow an airplane down is to increase angle of attack.

Essentially, pull the nose up, and the plane slows down. In an airplane, every control input always effects the others, so you must coordinate reducing power, increasing angle of attack, and adjusting trim.

The real job of wing flaps isn't to slow down the airplane, although they do slow you down in some cases by a whole lot. Instead, it's to keep the plane both flying and controllable once you do slow down. Every airplane's wing is designed with a certain goal in mind. In the case of a typical airliner, it's to fly really fast and high, with an eye towards fuel savings. Unfortunately, fast high-flying wings are really bad at flying low and slow. Since every successful flight ends low and slow, we need the flaps to essentially change the shape of the wing to one that will allow us to approach the runway at a safe speed. As a bonus, flaps allow us to point the nose of the airplane more downwards, giving a better view of the runway on approach.

Spoilers are almost cheating. What spoilers do is to stick up into the airflow, spoiling the lift generated by the wing, essentially making it quite inefficient. The spoilers will create some drag of their own, but really, they're making the plane descend quicker. Extending landing gear also provides more drag and helps slow the aircraft.

Once on the runway, airliners primarily use wheel brakes to decelerate after landing. Wing spoilers extend on the top of the wings which add aerodynamic drag, but they primarily kill the lift on the wings which places more weight on the wheels and improves braking. Thrust reversers are deployed on touchdown to both attenuate the thrust and to direct the thrust forward for deceleration purposes. Once the airspeed decelerates to about 60 knots, the reverse thrust is reduced to idle because that's when the possibility of the reverse exhaust flow could ingest foreign objects into the inlet of the engines.

Tricks To Increase Internet Speed In Android Mobile

Today we need to access internet most of the time, in whichever sectors or field you are working in. Internet is used by student to get more information on different topic, for business purpose to get the latest detail of the market and many more.

But in this most of the people use internet in their mobile and uses 2G services. In the beginning 2G gives good speed but after that it gives a very bad speed. Sometimes we just get irritated by using the bad speed internet.

The bad speed of mobile internet may occur due to several reasons like bad signal strength, congestion and load in network etc. None of the mobile company will guaranty you the plan with full speed. All mobile internet speed decreases after few time of usage.

In this article you’ll find out How to increase internet speed in Android mobile. The different tips and tricks to speed up your Internet in Android mobile are given in under given lines.

1. Clear the cache memory of your mobile. Never fill the cache memory of your mobile. Always remove the data, apps and information from your mobile which is no longer useful. This can increase the speed of internet in your mobile.
2. Never install too much of software in your mobile it will decrease the speed of internet in your mobile. Always uninstall the software which is no longer useful.
3. To increase the speed of internet in your mobile you can change the internet setting to load maximum KB data.
4. To increase the speed of internet in your mobile, if you are using it only for text then you should block images in your mobile. By this you can increase the mobile internet speed and will decrease the charge too. Like some provide charge per KG. And if you want to load then load low quality image.
5. Never download other applications while surfing.
6. Before using internet always make sure that you are using mobile internet in good network coverage, for good speed of internet in your mobile.
7. If you want good speed it your mobile then always load mobile view in opera mini.

I think that after reading this article you’ll be able to increase internet speed in your android mobile.