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 helicopter, meanwhile, was still awaiting a technological breakthrough. That's because it was a much more difficult mechanical problem to solve than was the fixed-wing airplane. Where airplanes get their lift from the wings, allowing for the use of a relatively modest engine for propulsion, helicopters rely on their rotors for both functions. Torque was another serious challenge--inventors kept trying new ways to counteract the twisting movement that was directed into the helicopter body from its large main rotor. Even today, helicopters are a noisier, shakier ride than their winged counterparts.
One hybrid approach that got a few tries over the years was the autogyro. The one in this undated photo (probably from the early 1930s) is a Pitcairn PAA-1. The big overhead rotor aside, it's got a pretty standard monoplane fuselage. Autogyros were a big deal, at least briefly--Amelia Earhart flew them, while Herbert Hoover heaped praise on manufacturer Harold Pitcairn.
Apparently, not much came of the Curtiss-Bleecker creation. The aircraft considered to be the first successful helicopter was the Breguets' Gyroplane-Laboratoire, which flew in 1935, followed about a year later by the Fa-61 of Heinrich Focke and Gerd Achghelis.
The , 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).
The , with its 600-horsepower engine, could ferry 10 passengers and 2 crew members, carry a load of more than 1,800 pounds, and cruise at 86 miles per hour. Its range was 265 miles, and its ceiling with a normal load was just over 10,000 feet. In use with the Marine Corps as well as the Coast Guard, it performed functions including search and rescue, heavy transport and antisubmarine warfare.
This picture, from May 1950, also shows a two-person in flight.
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 (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.
The Sea King, from Sikorsky Aircraft (now a division of United Technologies), had a crew of four, a ceiling of nearly 15,000 feet, a range of more than 500 nautical miles, and a cruising speed of 120 knots. One model of the Sea King, the Sikorsky VH-3D, has long served as the
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. 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 were ever built
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 from Bell/Agusta Aerospace, is now in development. The company expects to make its first deliveries in 2011.
In the early 1990s, 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.
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 , 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 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 , 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 , of Chandler, Ariz., which unveiled its A600 Talon this summer at the . 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 , 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