An aircraft constructed with a push-pull configuration has a combination of forward-mounted propellers and backward-mounted propellers. The earliest known examples of "push-pull" engined-layout aircraft include a trio of experimental German World War I designs: chronologically comprising the only Fokker twin-engined design of the period, the Fokker K. I from 1915. I triplane fighter design of late 1917, concluding with the laterally-offset "push-pull" Gotha G. VI bomber prototype of 1918. An early post-World War I example of a "push-pull" aircraft was the Short Tandem Twin: another was the Caproni Ca.1 of 1914 which had two wing-mounted tractor propellers and one centre-mounted pusher propeller. Around 450 of these and their successor, the Ca.3 were built. One of the first to employ two engines on a common axis was the one-off, ill-fated Siemens-Schuckert DDr. I fighter of 1917. Claudius Dornier embraced the concept, many of his flying boats using variations of the tandem "push-pull" engine layout, including the 1922 Dornier Wal, the 1938 Dornier Do 26, the massive 1929 Dornier Do X, which had twelve engines driving six tractors and six pushers.
A number of Farmans and Fokkers had push-pull engine installations, such as the Farman F.121 Jabiru and Fokker F.32. Push-pull designs have the engines mounted above the wing as Dornier flying boats or more on a shorter fuselage than conventional one, as for Rutan Defiant or Voyager canard designs. PINA Twin boomers such as the Cessna Skymaster and Adam A500 have the aircraft's tail suspended via twin booms behind the pusher propeller. In contrast, both the World War II-era Dornier Do 335 and the early 1960s-designed French Moynet M 360 Jupiter experimental private plane had their pusher propeller behind the tail. While pure pushers decreased in popularity during the First World War, the push-pull configuration has continued to be used; the advantage it provides is the ability to mount two propellers on the aircraft's centreline, thereby avoiding the increased drag that comes with twin wing-mounted engines. It is easier to fly if one of the two engines fails, as the thrust provided by the remaining engine stays in the centerline.
In contrast, a conventional twin-engine aircraft will yaw in the direction of the failed engine and become uncontrollable below a certain airspeed, known as VMC. The rear engine operates in the disturbed air from the forward engine, which may reduce its efficiency to 85% of the forward engine. In addition the rear engine can interfere with the aircraft's rotation during takeoff if installed in the tail, or they require additional compromise to be made to ensure clearance; this is. Pilots in the United States who obtain a multi-engine rating in an aircraft with this push-pull, or "centerline thrust," configuration are restricted to flying centerline-thrust aircraft; the limitation can be removed by further testing in a conventional multi-engine aircraft. Despite its advantages push-pull configurations are rare in military aircraft. In addition to the problems noted for civil aircraft, the increased risk to the pilot in the case of a crash or the need to parachute from the aircraft pose problems.
During a crash the rear engine may crush the pilot and if bailing out, the pilot is in danger of hitting the propeller. Examples of past military applications include the aforementioned Siemens-Schuckert DDr. I twin-engined triplane and the Gotha G. VI, with its engines mounted on rear ends of two separate fuselages. More successful was the Italian Caproni Ca.3 trimotor, with two tractor engines and one pusher. Between the wars, most push-pull aircraft were flying boats, of which the Dornier Wal was the most numerous, while a number of heavy bombers, such as the Farman F.220 used engines mounted in push-pull pairs under the wings. Near the end of World War II, the German Dornier Do 335 push-pull twin-engined, Zerstörer-candidate heavy fighter featured explosive charges to jettison the rear propeller and dorsal tailfin, a manually-jettisonable main canopy, as well as an ejection seat. One of the last military aircraft to use the configuration was the American Cessna O-2, used for forward air control during the Vietnam war.
Tractor configuration Pusher configuration Star Kraft SK-700 - 2 x 350hp 1000aircraftphotos.com
Haitian Air Corps
The Haiti Air Corps was a unit of the Armed Forces of Haiti. The corps was formed in 1943 with some former United States aircraft. In the late 1940s Haiti got its first fighter aircraft, an F-51 Mustang. Haiti in 1975 bought a Cessna O-2A Skymaster for the air corps; the corps was disbanded in 1994. Many of Haiti's air force aircraft were donated secondhand from the United States and France: North American Aviation F-51D Mustang fighters – 6 delivered 1950 and the last retired 1973/74, sold to Dominican Republic for parts. North American Aviation T-28 TrojanD fighter trainer – 12 ex-French Air Force delivered 1973 Cessna O-2A Skymaster – 8 observation aircraft delivered 1975 and sold to Dominican Republic for parts Lockheed AT-33 Strike aircraft lease from the USA Republic P-47 fighters received from the USA SIAI-Machetti S-211 jet trainer and put up for sale on 23 April 1990, 2 sold to United States private companies and 2 to Republic of Singapore Air ForceAermacchi SF.260TP Warrior trainer* O-57 Grasshopper de Havilland Canada DHC-2 Beaver/de Havilland Canada DHC-6 Twin Otter utility transport Curtiss-Wright C-46 Commando transport last seen in Uphold democracy.
Beechcraft Beech 18 light transport. Lockheed C-60 Lodestar Boeing S-307 Stratoliner Cessna 310 Douglas C-47 Dakota Beech 58 Baron Cessna 402 Utililiner IAI 201 Arava Piper PA-34 Seneca Cessna 303 Beech 65 Queen Air C-78 Bobcat Fairchild PT-19 trainer North American Aviation North American T-6G Texan trainer Vultee Aircraft Vultee BT-13A Valiant trainer. Beech Bonanza F33 trainer Cessna 150 – 3/Cessna 172 Skyhawk trainer Sikorsky S-55 utility helicopters Hughes Helicopters 269C utility/trainer helicopter – 3 Hughes Helicopters 369CC utility/trainer helicopter – 2 Sikorsky S-58T The Haiti Air Corps was active in Operation uphold democracy as a transport force. All of Haiti's combat aircraft were retired, Haiti air force at the time had: Two O-57 Grasshopper scout planes Three BT-13 Valiant trainer planes One C-78 Bobcat transport plane One C-46 Commando transport planeAll of the equipment was from WW2 and was in bad condition; the US Army captured two C-46 Commandos painted in Air Haiti markings and one was tracked to being a EX-US Navy plane.
The Haiti Air Corps is active as of 2013 and the state of the retired aircraft is not known, but many aircraft were sold as parts or secondhand aircraft. The SIAI-Machetti S-211 jet trainers were retired and put up for sale on 23 April 1990, 2 sold to United States private companies and 2 to Republic of Singapore Air Force, some of the F-51s and O-2As were given to the Dominican Republic for spare parts; some of the aircraft like the S-58Ts and O-2As can be seen as wrecks in junkyards. The current inventory consists of some trainers/Cessna light aircraft. Armed Forces of Haiti
A loudspeaker is an electroacoustic transducer. The most used type of speaker in the 2010s is the dynamic speaker, invented in 1925 by Edward W. Kellogg and Chester W. Rice; the dynamic speaker operates on the same basic principle as a dynamic microphone, but in reverse, to produce sound from an electrical signal. When an alternating current electrical audio signal is applied to its voice coil, a coil of wire suspended in a circular gap between the poles of a permanent magnet, the coil is forced to move back and forth due to Faraday's law of induction, which causes a diaphragm attached to the coil to move back and forth, pushing on the air to create sound waves. Besides this most common method, there are several alternative technologies that can be used to convert an electrical signal into sound; the sound source must be amplified or strengthened with an audio power amplifier before the signal is sent to the speaker. Speakers are housed in a speaker enclosure or speaker cabinet, a rectangular or square box made of wood or sometimes plastic.
The enclosure's materials and design play an important role in the quality of the sound. Where high fidelity reproduction of sound is required, multiple loudspeaker transducers are mounted in the same enclosure, each reproducing a part of the audible frequency range. In this case the individual speakers are referred to as "drivers" and the entire unit is called a loudspeaker. Drivers made for reproducing high audio frequencies are called tweeters, those for middle frequencies are called mid-range drivers, those for low frequencies are called woofers. Smaller loudspeakers are found in devices such as radios, portable audio players and electronic musical instruments. Larger loudspeaker systems are used for music, sound reinforcement in theatres and concerts, in public address systems; the term "loudspeaker" may refer to individual transducers or to complete speaker systems consisting of an enclosure including one or more drivers. To adequately reproduce a wide range of frequencies with coverage, most loudspeaker systems employ more than one driver for higher sound pressure level or maximum accuracy.
Individual drivers are used to reproduce different frequency ranges. The drivers are named subwoofers; the terms for different speaker drivers differ, depending on the application. In two-way systems there is no mid-range driver, so the task of reproducing the mid-range sounds falls upon the woofer and tweeter. Home stereos use the designation "tweeter" for the high frequency driver, while professional concert systems may designate them as "HF" or "highs"; when multiple drivers are used in a system, a "filter network", called a crossover, separates the incoming signal into different frequency ranges and routes them to the appropriate driver. A loudspeaker system with n separate frequency bands is described as "n-way speakers": a two-way system will have a woofer and a tweeter. Loudspeaker driver of the type pictured are termed "dynamic" to distinguish them from earlier drivers, or speakers using piezoelectric or electrostatic systems, or any of several other sorts. Johann Philipp Reis installed an electric loudspeaker in his telephone in 1861.
Alexander Graham Bell patented his first electric loudspeaker as part of his telephone in 1876, followed in 1877 by an improved version from Ernst Siemens. During this time, Thomas Edison was issued a British patent for a system using compressed air as an amplifying mechanism for his early cylinder phonographs, but he settled for the familiar metal horn driven by a membrane attached to the stylus. In 1898, Horace Short patented a design for a loudspeaker driven by compressed air. A few companies, including the Victor Talking Machine Company and Pathé, produced record players using compressed-air loudspeakers. However, these designs were limited by their poor sound quality and their inability to reproduce sound at low volume. Variants of the system were used for public address applications, more other variations have been used to test space-equipment resistance to the loud sound and vibration levels that the launching of rockets produces; the first experimental moving-coil loudspeaker was invented by Oliver Lodge in 1898.
The first practical moving-coil loudspeakers were manufactured by Danish engineer Peter L. Jensen and Edwin Pridham in 1915, in Napa, California. Like previous loudspeakers these used horns to amplify the sound produced by a small diaphragm. Jensen was denied patents. Being unsuccessful in selling their product to telephone companies, in 1915 they changed their target market to radios and public address systems, named their product Magnavox. Jensen was, for years after the invention of a part owner of The Magnavox Company; the moving-coil principle used today in speakers was patented in 1924 by Chester W. Rice and Edward W. Kellogg; the key difference between previous attempts and the patent by Rice and Kell
20th Attack Squadron
The 20th Attack Squadron is a United States Air Force unit, based at Whiteman Air Force Base, Missouri. It flies the General Atomics MQ-9 Reaper and is assigned to the 432d Wing at Creech Air Force Base, Nevada, it was activated as the 20th Transport Squadron in 1940 and served as a troop carrier unit in Panama during and after World War II, until it was inactivated in 1949. Activated in 1965 as the 20th Tactical Air Support Squadron, it served notably for seven and a half years of combat duty during the Vietnam War, was inactivated in 1973. While in inactive status, the two squadrons were consolidated into a single unit; the 20th TASS was reactivated at Shaw Air Force Base in 1990, again inactivated on 31 December 1991. The unit was redesignated as the 20th Reconnaissance Squadron and its reactivation at Whiteman took place on 14 January 2011. In May 2016, it was redesignated the 20th Attack Squadron The 20th Transport Squadron was activated at France Field, Panama Canal Zone, on 15 December 1940, but had only one officer and no airplanes until February 1941.
The squadron became operational by March 1941 when the Squadron obtained its first aircraft from France Field's 16th Air Base Squadron, a Douglas C-33. With this solitary aircraft, the Squadron undertook daily flights to Albrook Field and, from there, on to Rio Hato Field and return. By May, the squadron began starting with one to Managua, Nicaragua. Flying with two or three airplanes, the Squadron began the first of a series of cross-country flights to Trinidad in the British West Indies on 2 June 1941 to support the construction of the outer defense ring of air bases in the Caribbean after the United States obtained basing rights as part of the Destroyers for Bases Agreement with the British. By the time of the Pearl Harbor Attack on 7 December 1941, the unit had received six Douglas C-49s from the United States. On 22 November 1941, six of the C-49s were detached to Howard Field in the Canal Zone as part of what came to be known as Flight "B" of the squadron to work with the Army 501st Parachute Battalion and the 550th Airborne Infantry, which were training to act as a rapid deployment force in the Panama Canal defense scheme.
The squadron became the 20th Troop Carrier Squadron in July 1942 and flew many different types of aircraft, several being one of a kind. The Squadron moved from France Field to Howard Field on 19 February 1942; some aircraft were detached to Waller Field and Borinquen Field, Puerto Rico. Flight "A" left the squadron on 22 December 1941 when it was detached to the 92d Air Base Group at Waller Field, Trinidad; the C-47s were followed on 19 June by two Consolidated OA-10 Catalina amphibians and a locally procured Stinson C-91. It flew a single Junkers C-79 trimotor, given USAAF serial 42-52883, a Hamilton UC-89, a former Panamanian registered single-engine plane; these local acquisitions were a measure of the near-desperate need for transport aircraft being felt by the squadron and Sixth Air Force at the time. In March 1943, a pilot was dispatched to Santiago, Chile, to fly an Italian Savoia-Marchetti SM.81 tri-motor back to the Canal Zone. By early 1943, the unit had 234 enlisted. In January 1943, all of the 0A-10's were transferred to other units and the C-79, C-89 and C-91 were all grounded for extended periods as the ground crews attempted to deal with these non-standard aircraft.
By June 1943, all had been reassigned out of the squadron. One replacement aircraft received by the squadron was the huge Boeing XC-105, converted from bomber to heavy transport configuration to meet Sixth Air Force's peculiar requirements for long frequent over-water resupply flights to Seymour Field in the Galapagos Islands, but the unit got the first two Fairchild UC-61 Forwarders, a new Douglas C-47A and conducted long distance flights with cargo and personnel to resupply and evacuation of the small radar sites spotted around the periphery of the Canal. As Howard Field became more crowded with bomber units, the squadron moved in June 1943 to Albrook Field. By December 1943, the detachments in the Antilles, leading a separate existence from the "home" based Flight "A" in the Canal Zone, were detached from the squadron and became assets of the Antilles Air Command, based at Borinquen Field, Puerto Rico, but dispersed throughout the Antilles; the unit was redesignated as the 20th Troop Carrier Squadron on 13 November 1943.
By November 1944, the unit had started benefiting from the production of transport types in the United States, could approach some semblance of standardization in its fleet. The last year of the war, with the general wind-down of the size and breadth of Sixth Air Force, saw a gradual reduction in the hectic flight schedules for 20th crews. By this time, the Squadron had received some Curtiss C-46 Commandos. Routine transport operations within Panama and Central America continued, with a C-47 aiding a forest fire in the Peten region of Guatemala. After the end of the war, the squadron continued to provide transport for Caribbean Air Command, was equipped with Douglas C-54 Skymasters in 1946, it was attached to the 314th Troop Carrier Group, which moved to Albrook in October 1946. In July 1948, its heavy transports deployed to Germany to assist with the Berlin Airlift; the 20th moved from Panama to Bergstrom Air Force Base, Texas in September 1948. At Bergstrom, the squadron received Fairchild C-82 Packet medium transports in November 1948 and began tra
Yuma Proving Ground
Yuma Proving Ground is a United States Army proving ground and one of the largest military installations in the world. It is a subordinate command of the Army Evaluation Command. Located in southwestern La Paz County and western Yuma County in southwestern Arizona, U. S. about 30 miles north-east of the city of Yuma, it encompasses 1,307.8 square miles in the northwestern Sonoran Desert. The proving ground conducts tests on nearly every weapon in the ground combat arsenal. Nearly all the long-range artillery testing for U. S. ground forces takes place here in an area completely removed from urban encroachment and noise concerns. Restricted airspace controlled by the test center amounts to over 2,000 square miles. Yuma Proving Ground has the longest overland artillery range in the nation, the most instrumented helicopter armament test range in the Department of Defense, over 200 miles of improved road courses for testing tracked and wheeled military vehicles, over 600 miles of fiber-optic cable linking test locations, the most modern mine and demolitions test facility in the western hemisphere.
Realistic villages and road networks representing urban areas in Southwest Asia have been constructed and are used for testing counter-measures to the threat of roadside bombs. The General Motors Desert Proving Ground – Yuma opened at the proving ground in late July 2009. General Motors built the facility at a cost of more than $100 million after closing its desert automotive test facility in Mesa, in operation since 1953; the new facility allows Army automotive testers to test their wheeled vehicles all year-round. It is estimated that the track can be used to test about 80 percent of the Army's wheeled vehicle fleet. More than 3,000 people civilians, work at the proving ground, the largest employer in Yuma County. In a typical year, over 500,000 artillery and missile rounds are fired, 36,000 parachute drops take place, 200,000 miles are driven on military vehicles, over 4,000 air sorties are flown from the proving ground's Laguna Army Airfield. About 10 percent of the proving ground's workload is training.
In a typical year, dozens of units come to the facility for realistic desert training before deploying overseas. Yuma Proving Ground's clean air, low humidity, skimpy rainfall—only about 3 inches per year—and annual average of 350 sunny days, add up to perfect testing and training conditions. Urban encroachment and noise concerns are nonexistent problems, unlike at many other military installations. Of the four extreme natural environments recognized as critical in the testing of military equipment, three fall under the management authority of Yuma Proving Ground. Realistic natural environment testing ensures that American military equipment performs as advertised, wherever deployed around the world; the proving ground manages military equipment and munitions testing at three locations: The Cold Regions Test Center at Fort Greely, Alaska. The common link between these test centers is "environmental testing," which makes the proving ground the Army's environmental test expert. Yuma Proving Ground tests improvised explosive devices known as IEDs, the number-one killer of American service men and women in Iraq and Afghanistan.
Hundreds of Unmanned Aerial Vehicles fly at the proving ground each year from the six airfields located at the proving ground, as do helicopters and fixed-wing aircraft conducting personnel and cargo parachute drops. Many friendly foreign nations visit the proving ground to conduct test programs; the presence of the U. S. Army in Yuma goes back to 1850, when Fort Yuma was constructed on a hill overlooking the important Yuma crossing of the Colorado River. Soldiers at Fort Yuma maintained peace and protected the important Yuma crossing, used by thousands of travelers each year; the Army constructed a second facility in 1865, the Yuma Quartermaster Depot, to act as a supply base for Army posts throughout Arizona and parts of New Mexico. Supplies were transported from the depot to military outposts by wagon. After Fort Yuma and the Yuma Quartermaster Depot closed in the 1880s, the Army did not to return to Yuma on a permanent basis until World War II. Yuma Proving Ground traces its history to Camp Laguna and the Army Corps of Engineers Yuma Test Branch, both activated in 1943.
Located on the Colorado River, the Yuma Test Branch conducted testing on combat bridges, amphibious vehicles, boats. Tens of thousands of mechanized and infantry soldiers were trained at Camp Laguna for duty at combat fronts throughout the world, from North Africa to the South Pacific. Abandoned campsites and tank trails can still be found on the proving ground. Camp Laguna lasted only until the end of World War II; the Yuma Test Branch was closed in 1949 and reactivated two years as the Yuma Test Station, under the operational control of the Sixth U. S. Army. In 1962, the station was named Yuma Proving Ground and reassigned to the U. S. Army Materiel Command as an important component of the Test and Evaluation Command. On July 26, 1973, it received its full name—U. S. Army Yuma Proving Ground; the following year it was designated as a Department of Test Facility Base. Since its early days, Yuma Proving Ground has been a desert environmental test center for all types of military equipment and materiel.
However, developmental and a variety of other types of testing of artillery systems and ammunition, aircraft armament and targeting systems, mobility equipment
United States Air Force
The United States Air Force is the aerial and space warfare service branch of the United States Armed Forces. It is one of the five branches of the United States Armed Forces, one of the seven American uniformed services. Formed as a part of the United States Army on 1 August 1907, the USAF was established as a separate branch of the U. S. Armed Forces on 18 September 1947 with the passing of the National Security Act of 1947, it is the youngest branch of the U. S. Armed Forces, the fourth in order of precedence; the USAF is the largest and most technologically advanced air force in the world. The Air Force articulates its core missions as air and space superiority, global integrated intelligence and reconnaissance, rapid global mobility, global strike, command and control; the U. S. Air Force is a military service branch organized within the Department of the Air Force, one of the three military departments of the Department of Defense; the Air Force, through the Department of the Air Force, is headed by the civilian Secretary of the Air Force, who reports to the Secretary of Defense, is appointed by the President with Senate confirmation.
The highest-ranking military officer in the Air Force is the Chief of Staff of the Air Force, who exercises supervision over Air Force units and serves as one of the Joint Chiefs of Staff. Air Force components are assigned, as directed by the Secretary of Defense, to the combatant commands, neither the Secretary of the Air Force nor the Chief of Staff of the Air Force have operational command authority over them. Along with conducting independent air and space operations, the U. S. Air Force provides air support for land and naval forces and aids in the recovery of troops in the field; as of 2017, the service operates more than 5,369 military aircraft, 406 ICBMs and 170 military satellites. It has a $161 billion budget and is the second largest service branch, with 318,415 active duty airmen, 140,169 civilian personnel, 69,200 reserve airmen, 105,700 Air National Guard airmen. According to the National Security Act of 1947, which created the USAF: In general, the United States Air Force shall include aviation forces both combat and service not otherwise assigned.
It shall be organized and equipped for prompt and sustained offensive and defensive air operations. The Air Force shall be responsible for the preparation of the air forces necessary for the effective prosecution of war except as otherwise assigned and, in accordance with integrated joint mobilization plans, for the expansion of the peacetime components of the Air Force to meet the needs of war. §8062 of Title 10 US Code defines the purpose of the USAF as: to preserve the peace and security, provide for the defense, of the United States, the Territories and possessions, any areas occupied by the United States. The stated mission of the USAF today is to "fly and win...in air and cyberspace". "The United States Air Force will be a trusted and reliable joint partner with our sister services known for integrity in all of our activities, including supporting the joint mission first and foremost. We will provide compelling air and cyber capabilities for use by the combatant commanders. We will excel as stewards of all Air Force resources in service to the American people, while providing precise and reliable Global Vigilance and Power for the nation".
The five core missions of the Air Force have not changed since the Air Force became independent in 1947, but they have evolved, are now articulated as air and space superiority, global integrated intelligence and reconnaissance, rapid global mobility, global strike, command and control. The purpose of all of these core missions is to provide, what the Air Force states as, global vigilance, global reach, global power. Air superiority is "that degree of dominance in the air battle of one force over another which permits the conduct of operations by the former and its related land, sea and special operations forces at a given time and place without prohibitive interference by the opposing force". Offensive Counterair is defined as "offensive operations to destroy, disrupt, or neutralize enemy aircraft, launch platforms, their supporting structures and systems both before and after launch, but as close to their source as possible". OCA is the preferred method of countering air and missile threats since it attempts to defeat the enemy closer to its source and enjoys the initiative.
OCA comprises attack operations, sweep and suppression/destruction of enemy air defense. Defensive Counter air is defined as "all the defensive measures designed to detect, identify and destroy or negate enemy forces attempting to penetrate or attack through friendly airspace". A major goal of DCA operations, in concert with OCA operations, is to provide an area from which forces can operate, secure from air and missile threats; the DCA mission comprises both passive defense measures. Active defense is "the employment of limited offensive action and counterattacks to deny a contested area or position to the enemy", it includes both ballistic missile defense and air-breathing threat defense, encompasses point defense, area defense, high-value airborne asset defense. Passive defense is "measures taken to reduce the probability of and to minimize the effects of damage caused by hostile action without the intention of taking the initiative", it includes warning.
The Cessna Skymaster is a United States twin-engine civil utility aircraft built in a push-pull configuration. Its engines are mounted in the rear of its pod-style fuselage. Twin booms extend aft of the wings with the rear engine between them; the horizontal stabilizer is aft of the pusher propeller, mounted between and connecting the two booms. The combined tractor and pusher engines produce a unique sound; the Cessna O-2 Skymaster is a military version of the Cessna 337 Super Skymaster. The first Skymaster, Model 336 Skymaster, had fixed landing gear and flew on February 28, 1961, it went into production in May 1963 with 195 being produced through mid-1964. In February 1965, Cessna introduced the Model 337 Super Skymaster; the model was larger, had more powerful engines, retractable landing gear, a dorsal air scoop for the rear engine. In 1966, the turbocharged T337 was introduced, in 1973, the pressurized P337G entered production. Cessna built 2993 Skymasters of all variants, including 513 military O-2 versions.
Production in America ended in 1982, but was continued by Reims in France, with the FTB337 STOL and the military FTMA Milirole. The Skymaster handles differently from a conventional twin-engine aircraft in that if an engine fails, the plane will not yaw toward that engine. Without the issue of differential thrust inherent to conventional twins, engine failure on takeoff will not produce yaw from the runway heading. With no one-engine-out minimum controllable speed, in-flight control at any flying speed with an engine inoperative is not as critical as it is with engines on the wing with the associated leverage. Flying a Skymaster requires a pilot to hold a multiengine rating, although many countries issue a special "centerline thrust rating" for the Skymaster and other configured aircraft. Ground handling requires procedures; the rear engine tends to overheat and can quit while taxiing on hot days. Accidents have occurred when pilots, unaware of the shutdown, have attempted take-off on the nose engine alone, though the single-engine take-off roll exceeded the particular runway length.
Federal Aviation Administration Airworthiness Directive 77-08-05 prohibits single-engine take-offs and requires the installation of a placard marked "DO NOT INITIATE SINGLE ENGINE TAKEOFF". The Skymaster's unique sound is made by its rear pusher propeller slicing through turbulent air from the front propeller and over the airframe while its front tractor propeller addresses undisturbed air. From 1976 until the middle 1990s, the California Department of Forestry and Fire Protection used O-2 variants of the 337 Skymaster as tactical aircraft during firefighting operations; these were replaced with North American OV-10 Broncos, starting in 1993. From 1991 until 2001 the Cuban exile group Hermanos al Rescate used Skymasters, among other aircraft, to fly search and rescue missions over the Florida Straits looking for rafters attempting to cross the straits to defect from Cuba, when they found them, dropped life-saving supplies to them. Rescues were coordinated with the US Coast Guard, which worked with the group.
They chose Skymasters because their high wing offered better visibility of the waters below, they were reliable and easy to fly for long-duration missions, they added a margin of safety with twin-engine centerline thrust. In 1996, two of the Brothers to the Rescue Skymasters were shot down by the Cuban Air Force over international waters. Both aircraft were downed by a MiG-29, while a MiG-23, orbited nearby. 327 Baby Skymaster - reduced scale four-seat version of the 337, with cantilever wings replacing the 336/337 strut-braced configuration. It first flew in December 1967. One prototype was built before the project was cancelled in 1968 due to lack of commercial interest in the design; the prototype was delivered to NASA to serve as a full-scale model for wind tunnel testing. It was used in a joint Langley Research Center and Cessna project on noise reduction and the use of ducted versus free propellers. 336 Skymaster - production version powered by two 195 hp Continental IO-360-A engines, 195 built.
337 Super Skymaster - 336. 337A Super Skymaster - 337. 337B Super Skymaster - 337A. T337B Turbo Super Skymaster - 337B. 337D Super Skymaster - 337C. 337E Super Skymaster - 337D. 337F Super Skymaster - 337E. 337G Super Skymaster - 337F. P337G Super Skymaster - 337G. 337H Skymaster - 337G. P337H Pressurized Skymaster - T337G. 337M - US military version designated O-2 Skymaster in service, 513 built. O-2A - US military designation of the