جوک, پروکسی,دانلود,....

Designs by Maurice Leger, Jacques and Louis Breguet, and Paul Cornu all got off the ground in 1907--just barely, and for just a very few seconds. These earliest machines also tended to require steadying from people on the ground. Cornu's craft, shown here, got airborne in November of that year for as long as 20 seconds at an altitude, if you can call it that, of somewhere between knee-high and eye level. It featured two rotors at opposite ends of the airframe that turned in opposite directions to balance out the torque

The PV-2, which didn't progress past the prototype stage, featured a 90-horsepower Franklin engine, and the transmission was built mostly of junked auto parts, according to the NASM. The real innovations were in the rotors, especially in the way they were balanced.

The essence of this design, like that of PV-2 from Piasecki--a large main rotor and a small vertical tail rotor (just one of each)--has been the guiding force for most modern helicopters. Much of the credit for that design, and for turning helicopters into a practical reality, goes to Igor Sikorsky, a Russian immigrant to the U.S.

The Sikorsky R-4 saw limited action during the war, but for a few soldiers, its missions were of critical importance--it gets credit for the first helicopter rescue by U.S. Army Air Forces. At left in the back row here is Lt. Carter Harmon, the pilot for the combat rescue effort, which took place in April 1944 in the Burmese highlands. The minimal power of the R-4 engine meant that only one person could be evacuated at a time (three were airlifted in that first rescue).

While mainstream helicopters held to one of the two basic designs--the single large rotor of the R-4, or the tandem rotors of the flying banana--aeronautical research also branched off into other designs for vertical takeoff and landing. This is the Vertol VZ-2 (Model 76) in 1960; test flights of the VZ-2 ran from about 1957 to 1964. As with other VTOL aircraft, such as today's Osprey (more on that shortly), propellers on the wings also function as helicopter rotors when the wings are rotated skyward. Vertol Aircraft was started by Frank Piasecki after he left Piasecki Helicopter; it later was taken over by Boeing.

Not many aircraft have a theme song at all, let alone one as dramatic as the uber-operatic "Flight of the Valkyries" from Richard Wagner. But the Bell UH-1 Huey has been indelibly linked to that melody ever since Francis Ford Coppola's 1979 movie Apocalypse Now. The Huey was a considerable factor during the Vietnam War, where it served as a main means of transporting soldiers into and out of combat zones, and in many other utility roles. In this photo from 1967, a group of Marines patrols the demilitarized zone under the watchful presence of a well-armed Huey.

The first model entered service in the early 1960s, and over the years, the UH-1 became the most popular helicopter in history, appearing in both civilian and military contexts. Bell Helicopter still makes versions of it today.

Remember the autogyro? The concept lived on past the 1930s, as in the case of the McCulloch J-2 Aero Super Gyroplane, which NASA test-flew in the summer of 1973. Although the aircraft did get certified by the Federal Aviation Administration for commercial production, only a handful of J-2s were ever built

And the VTOL idea lives on, and lives large, in the Boeing V-22 Osprey. In this 1998 test flight, a development-stage Osprey carried a 6,500-pound Humvee at speeds up to 120 knots. Production of the often controversial tilt-wing aircraft is now under way. The U.S. Marine Corps has a small number of them already, some of which are scheduled to arrive in Iraq for combat duty shortly.

The Osprey has a three-person crew, and it can carry 24 passengers or up to 20,000 pounds of cargo. Boeing lists the aircraft's speed at 250 to 300 knots, with a range of 100 nautical miles when performing amphibious assault with troops.

A civilian counterpart, the BA609 Tiltrotor from Bell/Agusta Aerospace, is now in development. The company expects to make its first deliveries in 2011.

The Sikorsky S-64 Skycrane design, which dates back to the early 1960s, did away with all but the basic elements of a helicopter airframe so that a larger portion of the engine's power could go to lifting an external load. This flying-crane design is no longer in use by the military, which preferred to also have a cabin in the aircraft, but can still be found in commercial and other civilian operations such as transporting lumber or (with a water tank attached) fighting fires. S-64s can lift in excess of 20,000 pounds.

In the early 1990s, Erickson Air-Crane took over as the manufacturer of S-64s. Erickson's Helitankers carry a 2,650-gallon tank system and can spread both water and fire retardant.

This is what the U.S. Army prefers to use these days for heavy-lifting aerial duties: the CH-47 Chinook. The newest version of the tandem-rotor craft, the CH-47F, debuted in mid-August. Among the notable features of the upgrade is that the older analog gauges have been replaced with digital screens. The CH-47F has two 4,800-horsepower engines that can push it to a speed of 175 miles per hour and can hoist more than 21,000 pounds.

In this photo from December 2006, soldiers parachute out of an earlier model over Fort Lee, Va. The first Chinooks flew almost 50 years ago.

Some helicopters with two large rotors stack them, rather than place them forward and aft. The rotors spin in opposite directions to keep torque in check. This is the KA-27 Helix, from Russian manufacturer Kamov, landing on the cruiser U.S.S. San Jacinto in a training operation on the Baltic Sea several years ago.

This Russian helicopter remains a vivid reminder of the Cold War. It's the Mi-24 Hind, a fast, well-armed and heavily armored gunship that just plain looks mean. (It could also function as a troop carrier, with eight soldiers in its belly, but that was never a primary mission.) Although many patrolled the border between East and West Germany, the Hind saw the bulk of its combat action during the Soviet occupation of Afghanistan.

This one belongs to the U.S. military. In this photo from February 2000, it has just finished a day's work as an opposing-forces role player during a search-and-rescue exercise at the Naval Air Station in Fallon, Nev.

This rather ordinary-looking small helicopter is Boeing's newly designed A/MH-6X, flying for the first time in September 2006--for all of about 14 minutes, with a pilot. It is a prototype of military aircraft that could be either manned or unmanned, and is based on a demonstrator that has logged 500 hours of flight time over two years. The most significant modifications in the A/MH-6X, according to Boeing, are in the cockpit avionics and electrical systems. Network-centric features (networks becoming an ever more important factor for combat systems) include Ku-band communication, digital radios, IP-addressable aircraft systems, and on-board, high-bandwidth data processing

 

This, for instance, is the Northrop Grumman MQ-8B Fire Scout, which made its first flight in December 2006. Being designed in versions for both the Army and the Navy, it can fly at more than 125 knots, reach a ceiling of 20,000 feet, and lift 600 pounds. Flight time for the 9.5-foot-tall helicopter with a minimal payload is greater than eight hours, the company says. It's designed for missions including surveillance, reconnaissance and targeting.

Even as work goes on in the military-industrial complex, there are plenty of commercial enterprises looking to sell helicopters to private citizens for recreational and corporate use. One such company is Rotorway International, of Chandler, Ariz., which unveiled its A600 Talon this summer at the AirVenture air show in Oshkosh, Wis.. The two-seater can do long-distance cruises at 100 miles per hour--with the doors off, the company says--and can carry a "useful load" of 535 pounds, including 100 pounds in the luggage compartment.

The truly adventurous out there, meanwhile, might want to try something more like the Airscooter II, which in some ways is a throwback to the earliest days of helicopter flight. With a 65-horsepower, four-stroke engine, it weighs about 300 pounds and can travel at about 55 knots. The company plans to show it off next month at the Wired NextFest in Los Angeles