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22-505: Compared to that of the FJ-3, the FJ-4's new wing was much thinner, with a six percent thickness-to-chord ratio , and featured skin panels milled from solid alloy plates. It also had an increased area, and tapered more sharply towards the tips. Slight camber behind the leading edge improved low speed characteristics. The main landing gear design had to be considerably modified to fold wheel and strut within

44-440: A shock wave that produces a powerful form of drag known as wave drag , and gives rise to the concept of the sound barrier . The speed at which these shocks first form, critical mach , is a function of the amount of curvature. In order to reduce wave drag, wings should have the minimum curvature possible while still generating the required amount of lift. So, the main reason for decreasing the blade section thickness to chord ratio

66-648: A family resemblance was still present. The two prototypes had the same Wright J65-W-4 engine as the FJ-3, but production aircraft had the J65-W-16A of 7,700 lbf (34 kN) thrust. The first FJ-4 flew on 28 October 1954 and delivery began in February 1955. Of the original order for 221, the last 71 were modified in the FJ-4B fighter-bomber version. This had a stronger wing with six instead of four underwing stations and stronger landing gear. Additional aerodynamic brakes under

88-480: A lower critical Mach number, because a thicker wing deflects the airflow passing around it more than a thinner wing does, and thus accelerates the airflow to a faster speed. For instance, the fairly-thick wing on the P-38 Lightning has a critical Mach number of about .69. The aircraft could occasionally reach this speed in dives, leading to a number of crashes. The Supermarine Spitfire 's much thinner wing gave it

110-433: A minimum. For practical reasons, wings tend to be thickest at the root, where they meet the fuselage. For this reason, it is common for wings to taper their chord towards the tips, keeping the thickness-to-chord ratio close to constant, this also reduces induced drag at lower speeds. The crescent wing is another solution to the design to keep a relatively constant thickness-to-chord ratio. This aviation -related article

132-409: A wide range of speeds, like a modern airliner , requires these competing needs to be carefully balanced for every aircraft design. Swept wings are a practical outcome of the desire to have a low thickness-to-chord ratio at high speeds and a lower one at lower speeds during takeoff and landing . The sweep stretches the chord as seen by the airflow, while still keeping the wetted area of the wing to

154-406: Is a stub . You can help Misplaced Pages by expanding it . Critical mach In aerodynamics , the critical Mach number ( Mcr or M* ) of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound , but does not exceed it. At the lower critical Mach number , airflow around the entire aircraft is subsonic. Supersonic aircraft such as

176-575: Is to delay the compressibility effect related to higher Mach numbers, delaying the onset of a shock wave formation. The natural outcome of this requirement is a wing design that is thin and wide, which has a low thickness-to-chord ratio. At lower speeds, undesirable parasitic drag is largely a function of the total surface area , which suggests using a wing with minimum chord, leading to the high aspect ratios seen on light aircraft and regional airliners . Such designs naturally have high thickness-to-chord ratios. Designing an aircraft that operates across

198-475: The Concorde and combat aircraft also have an upper critical Mach number at which the airflow around the entire aircraft is supersonic. For an aircraft in flight, the speed of the airflow around the aircraft differs considerably in places from the airspeed of the aircraft; this is due to the airflow having to speed up and slow down as it travels around the aircraft's structure. When the aircraft's airspeed reaches

220-472: The English Electric Lightning , Lockheed F-104 , Dassault Mirage III , and MiG 21 , are intended to exceed Mach 1.0 in level flight, and are therefore designed with very thin wings. Their critical Mach numbers are higher than those of subsonic and transonic aircraft, but are still less than Mach 1.0. The actual critical Mach number varies from wing to wing. In general, a thicker wing will have

242-576: The Hawker Hunter and F-86 Sabre , were designed to fly satisfactorily even at speeds greater than their critical Mach number. They did not possess sufficient engine thrust to reach Mach 1.0 in level flight, but could do so in a dive and remain controllable. Modern jet airliners with swept wings, such as Airbus and Boeing aircraft, cruise at airspeeds faster than their critical Mach numbers but have maximum operating Mach numbers slower than Mach 1.0. Supersonic aircraft, such as Concorde , Tu-144 ,

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264-522: The Supermarine Spitfire , Bf 109 , P-51 Mustang , Gloster Meteor , He 162 , and P-80 , have relatively thick, unswept wings, and are incapable of reaching Mach 1.0 in controlled flight. In 1947, Chuck Yeager flew the Bell X-1 (also with an unswept wing, but a much thinner one), reaching Mach 1.06 and beyond, and the sound barrier was finally broken. Early transonic military aircraft, such as

286-445: The thickness-to-chord ratio , sometimes simply chord ratio or thickness ratio , compares the maximum vertical thickness of a wing to its chord . It is a key measure of the performance of a wing planform when it is operating at transonic speeds. At speeds approaching the speed of sound , the effects of Bernoulli's principle over curves on the wing and fuselage can accelerate the local flow to supersonic speeds. This creates

308-516: The F-1E and the FJ-4B the AF-1E. AF-1Es served with United States Naval Reserve units until the late 1960s. Data from American Military Aircraft General characteristics Performance Armament or several other configurations of rocket pods Related development Aircraft of comparable role, configuration, and era Related lists Thickness-to-chord ratio In aeronautics ,

330-533: The North American Rocketdyne AR-1 engine, installed in a fairing above the tail pipe of the jet engine. It ran on hydrogen peroxide and JP-4 jet fuel, and provided an additional 5,000 lbf (22 kN) of thrust for short periods. The FJ-4F reached speeds of Mach 1.41 and altitude of 71,000 ft (21,600 m). With the 1962 adoption of the Tri-Service aircraft designation system , the FJ-4 became

352-445: The aft fuselage made landing safer by allowing pilots to use higher thrust settings, and were also useful for dive attacks. External load was doubled. The most important characteristic of the FJ-4B, however, was that it was capable of carrying a nuclear weapon on the inboard port station. It was equipped with the LABS or Low-Altitude Bombing System for the delivery of nuclear weapons. The Navy

374-434: The airflow over the flight control surfaces lead to deterioration in control of the aircraft. In aircraft not designed to fly at or above the critical Mach number, the shock waves that form in the airflow over the wing and tailplane cause Mach tuck and may be sufficient to stall the wing, render the control surfaces ineffective, or lead to loss of control of the aircraft. These problematic phenomena appearing at or above

396-464: The contours of the new wing. The track of the main wheels was increased and because they were closer to the center of gravity, there was less weight on the nosewheel. Wing folding was limited to the outer wing panels. The FJ-4 was intended as an all-weather interceptor, a role that required considerable range on internal fuel. The FJ-4 had 50% more fuel capacity than the FJ-3 and was lightened by omitting armor and reducing ammunition capacity. The new wing

418-426: The critical Mach number were eventually attributed to the compressibility of air. Compressibility led to a number of accidents involving high-speed military and experimental aircraft in the 1930s and 1940s. The challenge of designing an aircraft to remain controllable approaching and reaching the speed of sound was the origin of the concept known as the sound barrier . 1940s-era military subsonic aircraft , such as

440-432: The critical Mach number, the speed of the airflow in some areas near the airframe reaches the speed of sound, even though the aircraft itself has an airspeed lower than Mach 1.0. This creates a weak shock wave . As the aircraft exceeds the critical Mach number, its drag coefficient increases suddenly, causing dramatically increased drag , and, in an aircraft not designed for transonic or supersonic speeds, changes to

462-408: Was "wet"; that is, it provided for integral fuel tankage. The fuselage was deepened to add more fuel, and had a distinctive " razorback " rear deck. A modified cockpit made the pilot more comfortable during the longer missions. The tail surfaces were also extensively modified and had a thinner profile. The overall changes resulted in an aircraft that had little in common with the earlier models, although

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484-558: Was eager to maintain a nuclear role in its rivalry with the Air Force, and it equipped 10 squadrons with the FJ-4B. It was also flown by three Marine squadrons. In April 1956 the Navy ordered 151 more FJ-4Bs, for a total of 152 FJ-4s and 222 FJ-4Bs produced, and 1,115 FJ aircraft of all variants delivered to the Navy and Marine Corps. The Navy ordered six FJ-4s to be converted to FJ-4F to test rocket engines, but only two were completed. These featured

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