History And Contributions Of Helicopters History Essay
The helicopter has earned a stout reputation as a workhorse for the myriad of tasks that they can perform. The ability of rotary wing aircraft to be able to not just fly in forward and reverse but to remain stationary in flight has helped American aviation in both the civilian and military realms. Tasks that would have previously required many more resources to complete or put additional workers at an increased risk have now been placed in the helicopter's lap. Rotary wing aviation may be young in practical applications but the technology is not new. American aviation would be augmented not by space age marvels but from technology based off of an ancient toy.
It is thought that the first instance of a man-made rotary wing device dates back to ancient China. Around 400BC a man by the name of Ge Hong had noticed how a sycamore seed fell to the ground in a circular fashion. Using the sycamore seed as inspiration he built a toy called the "bamboo dragonfly." It was a crude rotor system that featured feathers attached to a center stick. When spun in the hand the wings would lift the toy up and out of the user's hands (Gibbs-Smith, 1962; Samuels, 2006).
Leonardo da Vinci
The next major instance of rotary wing design comes from the famous artist Leonardo da Vinci. In 1483 da Vinci had designed what was called the "aerial screw" (Samuels, 2006). Though it is not believed to have been built, the design for this crude helicopter did incorporate an onboard power unit (Gibbs-Smith, 1962). Some of his writings would go on to highlight the importance of some of the aspects of modern aerodynamics we understand today: center of gravity, center of pressure, and streamlining (Aerospace: The Flight of Discovery, 1992).
Sir George Cayley
Sir George Cayley, known as the father of modern aerodynamics, had also studied the design of helicopters. Cayley had designed and built an unpowered helicopter glider that did fly, albeit only a few feet (Tucker, 2010). This was done using a design based upon an earlier helicopter toy created by Frenchmen Launoy and Bienvenu which took their design ultimately from those ancient Chinese toys (Gibbs-Smith, 1962). He felt that the original design could be perfected. His new designs would feature counter-rotating blades to help with the torque produced by a single rotor (Seddon, Newman, & Seddon, 2011) Sir George Cayley has been credited as stating "To be of ordinary use, they [flying machines] must be capable of landing at any place where there is space to receive them, and of ascending again from that point (Gibbs-Smith, 1962)." This would sum up precisely what helicopters should and would do.
Next we jump ahead to the 1930s with Russian immigrant Igor Sikorsky. Sikorsky had already established himself in aircraft design and construction through the S-38 clipper seaplane used extensively by Pan American Airlines as well as various other designs (Ingram & Stansell, 2010). He had dreamed for a long time of creating a rotary wing aircraft and had studied Leonardo da Vinci's designs (Turner, 2000). A German designer had created the first manned powered helicopter but it would be Sikorsky that would make the first mass produced design (Seddon, Newman, & Seddon, 2011). His VS-300 would be the first of Sikorsky's helicopters and through military support would become the R-4, a design using a single main rotor and a single tail rotor (Turner, 2000; Aerospace: The Flight of Discovery, 1992). Designs previous to this had two main rotors in tandem in order to counteract torque generated by a single rotor (Ingram & Stansell, 2010). The Sikorsky R-4 would be one of the first designs to be utilized in a theater of war. The U.S. Army and British Army would use them towards the end of WWII for rescue of downed aircrew in the Burma theater (Turner, 2000; Tucker, 2010).
We have seen how the modern design of helicopters progressed from simple toy to complex flying machine. The genie was out of the bottle and the capabilities were not lost on civil aviation in the U.S. The civilian populace has seen the helicopter used from rescue to construction work and agricultural use. It has helped to save countless lives and increase companies profits alike.
Medical and Lifesaving
The medical field has used the helicopter extensively in life-saving ambulance duties. With the introduction of helicopters first responders could now reach the scene of an accident in less time than a ground based ambulance. It would also allow rescuers to access areas that are either too remote or too distant (Chandrakanth & Bangalore, 2011). A good example of this would be medical rescues from offshore oil rigs (Ozdamar, 2011). These "air ambulances" would carry all necessary lifesaving equipment to treat trauma patients enroute to the hospital for further care. Over the last few decades the number of helicopters being utilized for civilian air ambulance has increased to nearly 900 (Chandrakanth & Bangalore, 2011). This increase in response time allows more lives saved through rapid treatment during what is known as the "golden hour" (Chandrakanth & Bangalore, 2011). This is the critical time for a trauma patient to receive advanced care and surgical intervention to prevent long-term damage to vital organs (Golden hour, 2009).
Besides carrying patients onboard the helicopter, it can also be utilized to carry supplies for disaster relief on an external cargo hook. This can allow a greater amount of needed supplies, such as vaccines, to reach those in need than a ground vehicle can. This is especially true if the roads to access the disaster area are impassable (Ozdamar, 2011).
It is from this external cargo capability where civilian aviation gains great use. Construction firms have used helicopters to aid in building construction where cranes might not be optimum or even possible. Igor Sikorsky again saw the potential of the helicopter in the cargo lifting role and designed what would become the crane helicopter or "Skycrane" (McKenna).
During a dissertation Sikorsky would mention the need for a helicopter of this particular type to transport items that when preassembled were too bulky to transport by other means. His aim was to be able to deliver items that were preassembled and ready to use thereby cutting down the overall construction time required (McKenna). One incident that showcases the need for helicopters, as well as those with cargo capabilities, would be in December of 1967. A Chevron offshore oil rig experienced an emergency and required a replacement 8,000 pound hydraulic pump be delivered to restart operations. At the time the weather was foul and would not permit normal sea-bound delivery (which on a normal day could take up to 26 hours). Within 22 minutes a Skycrane had delivered the much needed pump and restored operations which in turn saved Chevron financially (McKenna).
The electrical utility industry would utilize the unique capabilities of the helicopter but not for its cargo capability. Electric companies would seize the helicopter to perform daunting maintenance on high-power lines. The Tennessee Valley Authority, which contains a seven-state service territory and over 17,000 miles of power lines, has used helicopters for electrical line maintenance and inspection, setting poles, and stringing wire (Herring & Feerst, 2005). This availability helps to reduce maintenance times and costs using minimal crew. This is critical especially in times of severe weather when needing to inspect and repair power lines. The TVA can get maintenance teams, with tools, to any spot on the line in quicker time than a truck and give the electrician a more stable platform to work from at height (Herring & Feerst, 2005).
Farmers have used aircraft from an early start to help control their crops. Through the use of crop dusting farmers were able to keep pests from consuming crops and destroying a valuable source of income. Crop dusting would also be used to fertilize crops. Aviation had been seen as a time saver in that an airplane could cover a greater area in less time than a traditional machine. Helicopters would enable farmers to have even greater and more even coverage when spraying crops thanks to the ability to hover and enter tight, confined areas (Aerospace: The Flight of Discovery, 1992). The downwash created by a helicopters rotor system would be the key to an even distribution of chemicals. With this the chemicals would be dispersed more evenly to include the underside of plant leaves. Another of the advantages given a helicopter over an airplane is that a helicopter can refill at the farm without having to make a return trip to an airfield, thus saving time (Aerospace: The Flight of Discovery, 1992).
The U.S. military has always looked for what the next great weapon can be. The helicopter was certainly one of those. Almost as soon as Igor Sikorsky produced the R-4 in quantity the U.S. military has found ways to implement them to great success. Much like their civilian counterparts the military helicopter has been used in lifesaving, transportation of personnel and cargo, but also with a new combat role. The helicopter gunship has become an indispensable tool in the U.S. military's arsenal.
Before weapon technology advanced and military planners knew what helicopters really could accomplish they were being used as a rescue platform. Towards the end of WWII the U.S. used the Sikorsky R-4 to rescue flyers that were downed in the water or in other hard to reach areas in the Burma theater (Turner, 2000). This was normally accomplished through the use of PBY-4 Catalina seaplanes. The R-4 helicopter could get to those pilots that were in the dense jungle or near a coastline. This capability would decrease the amount of time that both the downed flyer and the rescue aircraft were subject to engagement or capture by the enemy. Also in 1944 an R-4 (belonging to the Coast Guard) helped to deliver blood plasma to sailors wounded during an explosion aboard a U.S. Navy destroyer (Seddon, Newman, & Seddon, 2011).
From these moments in the waning days of WWII the helicopter would always be seen as a method of saving lives on the battlefield. During the Korean War a Bell design would earn the moniker of "Angel of Mercy." The Bell H13 (Bell 47) was utilized extensively to rescue wounded soldiers from the battlefield and deliver them to Mobile Army Surgical Hospitals (Seddon, Newman, & Seddon, 2011; Driscoll, 2001). Thanks largely to the use of helicopters the mortality rate during the Korean War was 2.4%, the lowest to date for any major war (Driscoll, 2001).
From the WWII, to present day conflicts helicopters are still widely used by the U.S. military for medical evacuation contributing to continued low mortality rates. The Bell H13 would be replaced by the Bell UH-1 "Huey" and eventually the Sikorsky H-60 series.
Cargo and Utility Helicopters
The Korean War was the first war where the U.S. military found widespread use for the helicopter. The helicopter would be used for artillery spotting and observation giving the observer a better view of the battlefield for calling in artillery support. Unlike the fixed wing counterpart the helicopter could loiter for longer and operate from bases closer to the frontline (Samuels, 2006; Tucker, 2010).
Ground based combat units would come to utilize helicopters to transport not only personnel but much needed equipment by helicopter. With the use of helicopters ground commanders could reach areas previously unreachable through ground transportation or at least risk to lose valuable resources in effort. Helicopters could airlift artillery pieces to hilltops to quickly aid in ground support from high ground or deliver troops far behind enemy lines (Samuels, 2006).
The war in Vietnam would become largely known as a helicopter war due to the extensive use of helicopters to wage war. It was from this war that much of modern rotary wing warfare doctrine was derived. Though the U.S. Marine Corps had first pioneered "airmobile" helicopter warfare during the Korean War it wouldn't be until the Vietnam War that this practice was employed in a wide spread fashion (Tucker, 2010). Cargo would follow closely behind. Helicopters that were designed with cargo transport as a primary mission were entering the scene for much the same reason. In order to deliver crucial supplies to remote locations in substantial quantity the U.S. would use helicopters such as the CH-54 Tarhe (Sikorsky Skycrane), UH-34 Choctaw, SH-3 Sea King, CH-47 Chinook, and its smaller cousin the CH-46 Sea Knight (Tucker, 2010; Polmar, 2012). The CH-54 had a payload capacity of upwards of 20,000 pounds depending on the model (McKenna). Heavy lift helicopters could deliver artillery, light tanks, or even bridges to the frontlines. Very little was beyond the capability of the CH-54 (McKenna). To demonstrate the versatility of cargo aircraft the U.S. Navy utilized first the UH-34 then later the SH-3 for retrieval of crewmembers from the ocean as well as retrieval of NASA's Mercury, Gemini, and Apollo space capsules after re-entry and splashdown (Polmar, 2012).
The Vietnam War also saw the first uses of the gunship in combat. In previous wars the close combat support role was left to low flying propeller airplanes. The U.S. military found that helicopters could be a weapons platform given the ability to hover or operate in confined spaces without needing an improved airfield to conduct operations. Initially the U.S. military would use existing airframes such as the Bell UH-1 and attach offensive armament such as rockets and grenade launchers. Though crude it proved the gunship's worth and would lead to development of more advanced purpose built gunships such as the Bell AH-1 Cobra, the first attack helicopter (Tucker, 2010). So important and versatile was the AH-1 Cobra that the U.S. Marine Corps still utilizes the Cobra today. It has gone through several avionics upgrades to meet current military aviation demands (Update on Cobra-Huey upgrade program, 1996).
As technology advanced, with it too was the gunship. Using lessons learned from Vietnam the military looked for a new attack helicopter with even more capabilities. One of the early designs was the AH-56 Cheyenne. It could fly over 200 knots while carrying TOW anti-tank rockets and a 30mm cannon. It would also utilize advanced targeting systems. Ultimately this program would be cancelled in part to budget constraints (Prouty & Yackle, 1992). The next gunship to be developed and used to this day would be the Boeing AH-64 Apache. It can fly 180mph, up to 1,100 miles in range, and carry 2.75 inch rockets, Hellfire anti-tank missiles, and a 30mm cannon (Aerospace: The Flight of Discovery, 1992). This airframe would become a flying tank killer.
Presidential mission and the Osprey
One mission that showcases how important rotary wing aviation has become to the U.S. was the decision to use helicopters to transport the President of the United States, the First family, and other members of government. The U.S. Marine Corps squadron HMX-1 has largely used the VH-60N, and the VH-3D (Corps unveils new presidential helicopter, 2005). Both of these were modified from existing airframes in service in the military to serve in Very Important Person missions. The U.S. Marine Corps has looked into replacing their current fleet of presidential helicopters with the MV-22 Osprey (Sanborn, 2011).
The Osprey is already currently in use with the U.S. Marine Corps. This new airframe blurs the line between airplane and helicopter through use of large tilting engines and rotors. The MV-22 can start as a helicopter with the engines rotated vertically and mid-flight rotate the engines horizontal to fly as an airplane. This allows the Osprey great versatility in regards to areas of operation and mission types (Hanifen, 1995). The U.S. Marine Corps can use this airframe to transport cargo and equipment much like an airplane or cargo helicopter or insert a larger number of troops compared to the modernized UH-1 still in use by the U.S. Marines (Hanifen, 1995; Update on Cobra-Huey upgrade program, 1996). The U.S. Air Force has kept an eye on the Osprey as a contender for use as a combat search and rescue platform as part of its CSAR-X program thanks to its capabilities (Rotorcraft report, 2009).
Summary and Conclusion
Helicopter design started with humble beginnings as a toy in ancient China. Through the ages it has progressed to be a vital part of both civil and military applications. It has served in as many roles as the pioneers of the field can think of them. Countless lives have been saved by use of helicopters. Stranded mountain climbers and hikers or even people stranded due to natural disasters have come to expect rescue as a norm when before helicopters they would have been left to their own for survival.
The U.S. military has seen helicopters as a vital tool to bring the war to the enemy regardless of terrain. With them the military can press the attack from a closer distance bearing powerful weaponry and just as easily ensure wounded receive critical care in a timely manner. Mortality rates are at their lowest thanks in part to the ability to transport wounded quickly from the battle to the hospital. Next on the horizon are unmanned aircraft to do those missions deemed dull, dirty, or dangerous. The hover capability of unmanned helicopters lends itself to observation, attack, or resupply missions without exposing crews to unnecessary risk. Same can be said for any utility companies that join in the project. Use of unmanned helicopters for wire inspection or even police duties would decrease the work hour cost while maintaining the same workload.
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