Cessna T-37 Tweet
The Cessna T-37 Tweet is a small, economical twin-engined jet trainer type which flew for decades as a primary trainer for the United States Air Force and in the air forces of several other nations. The T-37C was additionally capable of some light attack duties; the A-37 Dragonfly variant served in the light attack role during the Vietnam War and continues to serve in the air forces of several South American nations. The T-37 served as the U. S. Air Force's primary pilot training vehicle for over 52 years after its first flight. After completing Primary in the Tweet, students moved on to other advanced Air Force, Marine Corps or Allied trainers. With a total of 1,269 Cessna T-37s built, the USAF retired its last T-37 in 2009; the Cessna Aircraft Company of Wichita, provided the United States Army during World War II and the Korean War with utility, light transport, observation aircraft the "O-1 Bird Dog" series. In the spring of 1952, the USAF issued a request for proposals for a "Trainer Experimental" program, specifying a lightweight, two-seat basic trainer for introducing USAF cadets to jet aircraft.
Cessna responded to the TX request with a twin-jet design with side-by-side seating. The USAF liked the Cessna design, given the company designation "Model 318", the side-by-side seating since it let the student and instructor interact more than with tandem seating. In the spring of 1954, the USAF awarded Cessna a contract for three prototypes of the Model 318, a contract for a single static test aircraft; the Air Force designated the type as XT-37. The XT-37 had a low, straight wing, with the engines buried in the wing roots, a clamshell-type canopy hinged to open vertically to the rear, a control layout similar to that of contemporary operational USAF aircraft, ejection seats, tricycle landing gear with a wide track of 14 ft, it first flew on 12 October 1954. The wide track and a steerable nosewheel made the aircraft easy to handle on the ground, the short landing gear avoided the need for access ladders and service stands; the aircraft was designed to be simple to maintain, with more than 100 access doors.
An experienced ground crew could change an engine in about half an hour. The XT-37 was aerodynamically clean, so much so that a speedbrake was fitted behind the nosewheel doors to help increase drag for landing and for use in other phases of flight. Since the short landing gear placed the engine air intakes close to the ground, screens pivoted over the intakes from underneath when the landing gear was extended, to prevent foreign object damage; the XT-37 was fitted with two Continental-Teledyne J69-T-9 turbojet engines, French Turbomeca Marboré engines built under license, with 920 lbf thrust each. The engines had thrust attenuators to allow them to remain spooled-up during landing approach, permitting shorter landings while still allowing the aircraft to make another go-around in case something went wrong. Empty weight of the XT-37 was 5,000 lb. Tests showed; the aircraft had a service ceiling of 35,000 feet but was unpressurized so was limited to an operational ceiling of 25,000 feet by USAF regulations.
The initial prototype crashed during spin tests. Prototypes had new features to improve handling, including long strakes along the nose, an extensively redesigned and enlarged tail. After these modifications, the USAF found the aircraft acceptable to their needs, ordered it into production as the T-37A. Production aircraft remained tricky in recovering from a spin; the production T-37A was similar to the XT-37 prototypes, except for minor changes to fix problems revealed by the flight-test program. The first T-37A was completed in September 1955 and flew that year; the T-37A was noisy by the standards of jet aircraft. The intake of air into its small turbojets emitted a high-pitched shriek that led some to describe the trainer as a "Screaming Mimi", it was referred to as the "6,000 pound dog whistle" or "Converter"; the piercing whistle gave the T-37 its name: "Tweety Bird", or just "Tweet". The Air Force spent a lot of time and money soundproofing buildings at bases where the T-37 was stationed, ear protection remains mandatory for all personnel when near an operating aircraft.
The Air Force ordered 444 T-37As, with the last produced in 1959. In 1957, the US Army evaluated three T-37As for battlefield observation and other combat support roles, but procured the Grumman OV-1 Mohawk, instead; the Air Force considered it to be underpowered. The new engines were more reliable. Improved avionics were specified for the new variant. A total of 552 newly built T-37Bs was constructed through 1973. All surviving T-37As were upgraded to the T-37B standard, as well. Due to a series of accidents caused by bird strikes between 1965 and 1970, all T-37s were retrofitted with a new windshield made of Lexan polycarbonate plastic 0.5 in thick, which could tolerate the impact of a 4 lb bird at a relative speed of 288 mph. In 1962, Cessna suggested the T-37B as a replacement for the North American F-100 Super Sabre as the primary aircraft for the USAF aerobatic demonstration team, the Thunderbirds, but the USAF was satisfied with the F-100; the T-37A and T-37B had no built-in armament and no stores pylons for external armam
The T-37A was a Soviet amphibious light tank. The tank is referred to as the T-37, although that designation was used by a different tank which never left the prototype stage; the T-37A was the first series of mass-produced amphibious tanks in the world. The tank was first created in 1932, based on the British Vickers tankette and other operational amphibious tanks; the tank was mass-produced starting in 1933 up until 1936, when it was replaced with the more modern T-38, based on the T-37A. Overall, after four years of production, 2552 T-37A’s were produced, including the original prototypes. In the Red Army, they were used to perform tasks in communication, as defense units on the march, as well as active infantry support on the battlefield; the T-37A were used in large numbers during the Soviet invasion of Poland and in the Winter War against Finland. The T-37 A was used by the Soviets in the beginning of the Great Patriotic War, but most of them were lost. Surviving tanks of that type fought on the front lines until 1944, were used in training and auxiliary defense until the end of World War II.
The Carden-Loyd tankettes by Carden-Loyd Tractors, Ltd. were promising enough that the company was purchased by Vickers-Armstrong. They developed floating tanks to General Staff requirements. In April 1931, Vickers-Armstrongs conducted several successful tests of these light vehicles in the presence of the press. Publication of the design and testing by the press attracted the attention of the Department of Motorization and Mechanization of the Workers'–Peasants' Red Army, because the small tank was well suited to the new armament policies of the Red Army, as well as being able to replace the older T-27 tankette, which never performed well in combat. At the Bolshevik OKMO plant in Leningrad, from the All Russian Co-Operative Society, newspapers were handed in containing information about the British tankette, as well as photographs and technical specifications. Based on this information, Soviet engineers found out that the power plant of the Carden-Loyd tankette was from a light tractor produced by the company, thus the overall layout must be similar.
Accordingly, the Selezen program was established in order to construct a similar amphibious tank with a layout based on that of the British prototype. The first Selezen prototype, designated the T-33, was built in March 1932 and showed good buoyancy during testing. However, the T-33 did not perform satisfactorily in other tests and was too complicated for the existing military-industrial complex to produce; as a result, it was not equipped in large numbers. Before the construction of the T-33, it was decided to increase the scale of work dedicated to creating an amphibious tank. In addition to the Leningrad OKMO, the Number 2 plant of the All-Soviet Automotive Union, producing armored vehicles for the Red Army, was relegated to the development and production of amphibious armored vehicles; as a result, at the 2nd VATO plant, under the supervision of N. N. Kozyrev, the T-41 amphibious tank was produced, weighing 3.5 tons and using the GAZ-AA engine, based on the T-27 power plant. The transmission was nearly identical to that of the T-27, to the power take-off for the propeller, they added a rigid gear clutch.
Its construction for turning off the propeller demanded stopping the tank and turning off the engine. The chassis was, in part, borrowed from the T-33, the caterpillar tracks were from the T-27. Leningrad builders continued the development of a more suitable amphibious tank, they designated their latest model as the “T-37”, it had the same GAZ AA engine as the T-41, the same transmission, wide use of automotive parts, the Krupp chassis, which Soviet engineers first encountered as a result of a technological partnership with Weimar Germany. Although the T-41 was produced for the military in small numbers, after testing and battlefield trials the T-37 was denied production due to various minor faults and an incomplete development process. Meanwhile, an opportunity to analyze the British prototype itself appeared; the British Army declined to put the Vickers prototype into service, so the company decided to look for foreign buyers. Interested since the April 1931 demonstration, the USSR, on February 5, 1932, made an offer, through Arcos representative Y.
Skvirskiy, for the purchase of eight vehicles. Talks about filling the order did not drag on, by June 1932, Vickers had produced and shipped two of the first tanks for the Soviets, it is thought that the T-37A was a copy of the Vickers floating tank, with the Soviet purchase of such tanks in mind. However, closer examination of the turn of events leads to the discrediting of such a theory, but it is true that the Soviet T-37A prototypes were influenced by the British models. Nikolai Astrov, a Soviet engineer, having worked hard on the T-37A prototypes, wrote in his memoirs that "peace be unto the T-37A, born “Vickers-Carden-Loyd." Before the end of 1932, the high command of the Red Army was planning to order 30 T-37A’s. In order to facilitate faster production, Factory No. 37 was handed over all OKMO production related to the T-37, as well as one British Vickers tank. In 1933, the No. 37 plant was given an order of 1200 T-37A’s. However, the events that followed showed the excessive optimism shown by the leadership of the trust responsible for the factory.
The trust itself was formed as a governing organ for coordinating large-scale efforts to develop new models of armored vehicles in a number of plants across the
M41 Walker Bulldog
The M41 Walker Bulldog 76-mm Gun Tank, M41, was an American light tank developed for armed reconnaissance purposes. It was produced by Cadillac between 1951 and 1954 and marketed to the United States Army as a replacement for its aging fleet of World War II vintage M24 Chaffee tanks. Although engineered first and foremost as a reconnaissance vehicle, the M41's weight and armament made it effective in the close infantry support role and for rapid airborne deployments. Upon entering US service, all M41s received the designation Little Bulldog and subsequently, Walker Bulldog after the late General Walton Walker, killed in a Jeep accident in 1950; the M41 was the first postwar American light tank to see worldwide service, was exported in considerable numbers by the US to Asia. Development of the M41 proceeded until the outbreak of the Korean War, when the US Army's renewed demands for more tanks resulted in its being rushed into production; the haste with which it was produced led to a number of technical problems, coupled with the cramped dimensions of its hull interior, gave it a somewhat mediocre reputation among American tank crews.
It was considered too large in comparison to the Chaffee for a reconnaissance asset. Funding for the M41 program was slashed accordingly, more emphasis placed on the development of new medium tanks such as the M47 Patton. Cadillac ceased production of the M41 in late 1954, it was not in US service long before being replaced by the M551 Sheridan during the 1960s. Beginning in 1946, the United States Army commissioned a project to oversee the replacement of the M24 Chaffee light tank in the reconnaissance role. For preliminary purposes this hypothetical tank was to be known as T37. However, in the wake of World War II most armored vehicle development programs suffered from a lack of impetuous and inadequate funding; the T37 concept did not reach viability until 1949, when three disparate prototypes were built. The second prototype of the trio, T37 Phase Two, was selected for further testing and received a unique designation, T41. In its final, pre-production form this model was known as T41E1 to the US Army.
The T41E1 was envisaged as a mobile light tank, capable of undertaking aggressive reconnaissance and being sufficiently armed to engage the latest Soviet medium tanks if necessary. It was to utilize automotive parts and components common to other US military vehicles and incorporate a modular hull capable of being converted for a variety of other specialized roles. For example, the US Army requirement called not only for a light tank, but an air defense platform and an armored personnel carrier based on the same chassis. A specific powerplant had been pre-selected for all three proposed vehicles: a Continental or Lycoming six-cylinder, air-cooled gasoline engine; this made the T41E1 one of the first American tanks to be designed around a preexisting engine type, rather than being built first and adopting a suitable engine. Weighing nearly 52,000 pounds, the T41E1 was so heavy it would have been classed as a medium tank in its own right only about five years earlier, was no longer deemed suitable for frequent airborne deployments.
The Army placed orders for the T41 circa August 1950. The tank was christened the "Walker Bulldog" — after the late General Walton Walker, killed in a Jeep accident a year earlier — at a demonstration for President Harry S. Truman at Aberdeen Proving Ground in February 1951. Serial production was delayed by technical difficulties stemming from the decision to incorporate an integral rangefinder directly into the steel turret. A renewed sense of urgency introduced by the outbreak of the Korean War and increasing demands by the US Army for more tanks resulted in production hurriedly commencing in mid-1951; the hasty production cycle led to numerous modifications during the course after manufacture. Cadillac repurposed a warehouse in Cleveland in August 1950 and began outfitting the location for production of the Walker Bulldog and other combat vehicles, namely the Cadillac M42 Duster; the plant, employing 3700, delivered the first production M41 Walker Bulldog in March 1951. The first eight Bulldogs were delivered to the US Army in July.
By March 1952 over 900 M41s had been manufactured. These entered service too late to take part in the Korean War, though some may have been shipped out to US forces in that region just as the fighting ended. 1,802 were built, but these suffered from a variety of technical issues due to their somewhat rushed production, a second mark, the M41A1, was introduced to correct these problems. Over 4,000 engineering design changes were requested by the US Army between July 1951 and July 1952. Approval to issue the M41 type to regular units was denied until December 1952, when the new mark was introduced. Another 1,631 baseline M41s were relegated to storage at the Ordnance Corps Depot in Lima, Ohio until their deficiencies could be corrected; the M41A1 was superseded by the M41A2 and M41A3, which had the advantage of greater ammunition stowage, simplified gun and turret systems. Despite these detail improvements, the M41 series did not prove popular in US service. Crew members seated in the turret complained of limited interior space.
Reconnaissance units criticized the height and size of the design, which reduced its ability to reconnoiter discreetly, although it was intended for deployment with airborne units its rather excessive weight made it impractical for airdrops. This led to the development of the M551 Sheridan, designed for airdrops, in which low combat weight was considered a key factor. M41 production ceased around late 1954, allowing the US Army to refocus on
T37 is a disability sport classification for disability athletics in track and jump events. It includes people who have coordination impairments such as hypertonia and athetosis, it is the athletics equivalent of the more general CP7 classification. This classification is for disability athletics in jump events; this classification is one of seven classifications for athletes with cerebral palsy. Similar classifications are T32, T33, T34, T35, T36, T38; the Australian Paralympic Committee defines this classification as being for "Moderate to minimal hemiplegia. Good functional ability in non affected side. Walks / runs without assistive devices, but with a limp." The International Paralympic Committee defined this classification on their website in July 2016 as, "Coordination impairments". Multiple types of disabilities are eligible to compete in this class; this class includes people who have cerebral palsy, or who have had a stroke or traumatic brain injury. Their running form manifests, their disability manifests itself less.
CP7 sportspeople are able to walk, but appear to do so while having a limp as one side of their body is more effected than the other. They may have involuntary muscles spasms on one side of their body, they have fine motor control on their dominant side of the body, which can present as asymmetry when they are in motion. People in this class tend to have energy expenditure similar to people without cerebral palsy. Athletes in this class are not required to use a starting block, it is up to the individual. They have the option to start from a standing position or 3 point stance; because of their disability, athletes may make movements that would disqualify them as a false start. If an official believes movement could be a result of this, they can restart the entire field without disqualifying any runners. There are a number of track and field events open to this class at various international competitions. Many have their own minimum qualifying scores; the classification was created by the International Paralympic Committee and has roots in a 2003 attempt to address "the overall objective to support and co-ordinate the ongoing development of accurate, reliable and credible sport focused classification systems and their implementation."
Classification into this class is handled by the International Paralympic Committee. For national events, classification is handled by the national athletics organization. Athletes with cerebral palsy or similar impairments who wish to compete in para-athletics competition must first undergo a classification assessment. During this, they both undergo a bench test of muscle coordination and demonstrate their skills in athletics, such as running or jumping. A determination is made as to what classification an athlete should compete in. Classifications may be Review status. For athletes who do not have access to a full classification panel, Provisional classification is available.