Zoom climb
Encyclopedia
A zoom climb is a climb
where the rate of climb
is greater than the maximum for a sustained climb, as determined from the thrust
of the aircraft's engines. During a zoom climb, the aircraft accelerates to a high air speed at an altitude at which it can operate in sustained level flight. The pilot then turns steeply upward, trading the kinetic energy
of forward motion for altitude. During these maneuvers the engine is in full thrust. The aircraft gains potential energy
(altitude) at the expense of kinetic energy
(forward motion). This is different from a steady climb, where the increase in potential energy comes from mechanical work
done by the engines, rather than from the aircraft's kinetic energy.
In a demonstration of their performance, English Electric Lightning
fighter aircraft
have sometimes used zoom climbs to climb above a Lockheed U-2
(which cruises at an altitude above the Lightning's service ceiling
), before pouncing on it from above.
During the Second World War, MiG-3 pilots utilized zoom climbs and subsequent descents to maintain a speed advantage over German fighters.
Zoom climbs have been used to test new aircraft designs and conduct research in different flight regimes. During the proving phase of the McDonnell Douglas
F-4 Phantom II
, on December 6, 1959 an early version of the aircraft the XF4H-1 performed a zoom climb to a world record 98,557 feet (30,040 m) as part of Operation `Top Flight'. The previous record of 94,658 feet (28,852 m) was set by a Soviet
Sukhoi
T-43-1 prototype. Commander Lawrence E. Flint Jr. accelerated his aircraft to Mach
2.5 at 47,000 feet (14,330 m) and climbed to 90,000 feet (27,430 m) at a 45-degree angle. He then shut down the engines and glided to the peak altitude. As the aircraft fell through 70,000 feet (21,300 m), Flint restarted the engines and resumed normal flight.
An F-104 Starfighter
fitted with an additional rocket engine
was also regularly used in zoom climb research for future spaceflight. On May 7, 1958, the aircraft reached an altitude of 91,249 feet (27.81 km) in a zoom climb at Edwards Air Force Base, Calif., setting a new altitude record. The Mach 2 mission took the airplane so high that the standard F-104’s jet engines routinely exceeded their temperature limits and had to be shut down. Sometimes the engine simply flamed out for lack of air. Then the pilot steered the aircraft like a returning spaceship to a lower altitude, where he would restart the engine.
Without engine power, the cockpit would depressurize on these missions. Consequently, for protection against the rarified atmosphere, the pilot wore a full-body pressure suit
. Properly outfitted with an airtight helmet and suit the pilot received breathing oxygen without ill effects.
Climb
thumb|right|An [[Embraer ERJ 145]] climbingIn aviation, the term climb refers both to the actual operation of increasing the altitude of an aircraft and to the logical phase of a typical flight following take-off and preceding the cruise, during which an increase in altitude to a predetermined...
where the rate of climb
Rate of climb
In aeronautics, the rate of climb is an aircraft's vertical speed - the rate of change in altitude. In most ICAO member countries , this is usually expressed in feet per minute and can be abbreviated as ft/min. Elsewhere, it is commonly expressed in metres per second, abbreviated as m/s...
is greater than the maximum for a sustained climb, as determined from the thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
of the aircraft's engines. During a zoom climb, the aircraft accelerates to a high air speed at an altitude at which it can operate in sustained level flight. The pilot then turns steeply upward, trading the kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
of forward motion for altitude. During these maneuvers the engine is in full thrust. The aircraft gains potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...
(altitude) at the expense of kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
(forward motion). This is different from a steady climb, where the increase in potential energy comes from mechanical work
Mechanical work
In physics, work is a scalar quantity that can be described as the product of a force times the distance through which it acts, and it is called the work of the force. Only the component of a force in the direction of the movement of its point of application does work...
done by the engines, rather than from the aircraft's kinetic energy.
English Electric Lightning
The English Electric Lightning is a supersonic jet fighter aircraft of the Cold War era, noted for its great speed and unpainted natural metal exterior finish. It is the only all-British Mach 2 fighter aircraft. The aircraft was renowned for its capabilities as an interceptor; Royal Air Force ...
fighter aircraft
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
have sometimes used zoom climbs to climb above a Lockheed U-2
Lockheed U-2
The Lockheed U-2, nicknamed "Dragon Lady", is a single-engine, very high-altitude reconnaissance aircraft operated by the United States Air Force and previously flown by the Central Intelligence Agency . It provides day and night, very high-altitude , all-weather intelligence gathering...
(which cruises at an altitude above the Lightning's service ceiling
Service ceiling
With respect to aircraft, a ceiling is the maximum density altitude an aircraft can reach under a set of conditions.The word ceiling can also refer to the height of the lowest obscuring cloud layer above the ground.-Service ceiling:...
), before pouncing on it from above.
During the Second World War, MiG-3 pilots utilized zoom climbs and subsequent descents to maintain a speed advantage over German fighters.
Zoom climbs have been used to test new aircraft designs and conduct research in different flight regimes. During the proving phase of the McDonnell Douglas
McDonnell Douglas
McDonnell Douglas was a major American aerospace manufacturer and defense contractor, producing a number of famous commercial and military aircraft. It formed from a merger of McDonnell Aircraft and Douglas Aircraft in 1967. McDonnell Douglas was based at Lambert-St. Louis International Airport...
F-4 Phantom II
F-4 Phantom II
The McDonnell Douglas F-4 Phantom II is a tandem two-seat, twin-engined, all-weather, long-range supersonic jet interceptor fighter/fighter-bomber originally developed for the United States Navy by McDonnell Aircraft. It first entered service in 1960 with the U.S. Navy. Proving highly adaptable,...
, on December 6, 1959 an early version of the aircraft the XF4H-1 performed a zoom climb to a world record 98,557 feet (30,040 m) as part of Operation `Top Flight'. The previous record of 94,658 feet (28,852 m) was set by a Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
Sukhoi
Sukhoi
Sukhoi Company is a major Russian aircraft manufacturer, headquartered in Begovoy District, Northern Administrative Okrug, Moscow, famous for its fighters...
T-43-1 prototype. Commander Lawrence E. Flint Jr. accelerated his aircraft to Mach
Mach number
Mach number is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure...
2.5 at 47,000 feet (14,330 m) and climbed to 90,000 feet (27,430 m) at a 45-degree angle. He then shut down the engines and glided to the peak altitude. As the aircraft fell through 70,000 feet (21,300 m), Flint restarted the engines and resumed normal flight.
An F-104 Starfighter
F-104 Starfighter
The Lockheed F-104 Starfighter is a single-engine, high-performance, supersonic interceptor aircraft originally developed for the United States Air Force by Lockheed. One of the Century Series of aircraft, it served with the USAF from 1958 until 1969, and continued with Air National Guard units...
fitted with an additional rocket engine
Rocket engine
A rocket engine, or simply "rocket", is a jet engineRocket Propulsion Elements; 7th edition- chapter 1 that uses only propellant mass for forming its high speed propulsive jet. Rocket engines are reaction engines and obtain thrust in accordance with Newton's third law...
was also regularly used in zoom climb research for future spaceflight. On May 7, 1958, the aircraft reached an altitude of 91,249 feet (27.81 km) in a zoom climb at Edwards Air Force Base, Calif., setting a new altitude record. The Mach 2 mission took the airplane so high that the standard F-104’s jet engines routinely exceeded their temperature limits and had to be shut down. Sometimes the engine simply flamed out for lack of air. Then the pilot steered the aircraft like a returning spaceship to a lower altitude, where he would restart the engine.
Without engine power, the cockpit would depressurize on these missions. Consequently, for protection against the rarified atmosphere, the pilot wore a full-body pressure suit
Pressure suit
A pressure suit is a protective suit worn by high-altitude pilots who may fly at altitudes where the air pressure is too low for an unprotected person to survive, even breathing pure oxygen at positive pressure. Such suits may be either full-pressure or partial-pressure...
. Properly outfitted with an airtight helmet and suit the pilot received breathing oxygen without ill effects.