Lockheed NF-104A
Encyclopedia
The Lockheed NF-104A was an American
mixed power, high-performance, supersonic
aerospace
trainer
that served as a low cost astronaut
training vehicle for the X-15 and projected X-20 Dyna-Soar
programs.
Three aircraft were modified from existing Lockheed F-104A
airframes and served with the Aerospace Research Pilots School
between 1963 and 1971, the modifications included a small supplementary rocket engine
and a reaction control system
for flight in the upper atmosphere
. During the test program the maximum altitude
reached was over 120,000 ft (36,600 m). One of the aircraft was destroyed in an accident while being flown by Chuck Yeager
. The accident was depicted in the book The Right Stuff
and the film of the same name.
Experimental Flight Test Pilot's School at Edwards Air Force Base
was renamed the Aerospace Research Pilots School
(ARPS), with the emphasis on training moving away from the traditional test pilot course to a more spaceflight oriented curriculum.
program. These maneuvers were commenced at 12000 ft (3,657.6 m) where the F-104 engine was throttled back to 80% power; and with the flaps, speedbrakes and landing gear extended, the aircraft was established in a 30˚ dive with a pull-out for the landing flare starting at 1500 ft (457.2 m) above the ground. These glide approaches gave little room for error.
A modified Gulfstream G-II
has been used by NASA
for similar training for the Space Shuttle
program.
It was realized that normal aircraft control surfaces had little or no effect in the thin atmosphere of the stratosphere
and that any aircraft operating at extremely high altitudes would need to be equipped with a reaction control system
(RCS). A modified version of the Bell X-1
was used for initial RCS tests, but was grounded after technical problems and was replaced with a NASA-modified Lockheed F-104A (55-2961) in 1959 which carried RCS systems on its wing tips and in the fuselage nose. This aircraft (designated JF-104) achieved a maximum altitude of 83000 ft (25,298.4 m) during the test program. Pilots who flew this aircraft included Neil Armstrong
who gained valuable experience in using the RCS system.
Pilots complained that the instrument displays were difficult to read and were not accurate enough for the critical zoom climb profiles required to reach high altitudes.
was awarded a contract by the USAF to modify three F-104A aircraft for the dedicated role of aerospace trainer (AST) in 1962. The airframes were taken out of storage at AMARC and transported to the company factory for modification.
of the NF-104A was increased by adding tip extensions to the existing planform
. This modification was needed to house the RCS roll control thrusters and would also decrease the type's wing loading
.
nose radome was replaced with an aluminum skin and housed the pitch and yaw RCS thrusters.
The air intakes originally designed by Ben Rich
were of the same fixed geometry as the F-104A but included extensions to the inlet shock cones for optimum jet engine operation at higher Mach number
s.
Internal fuselage
differences included provision for rocket fuel oxidizer tanks, deletion of the M61 Vulcan
cannon, Radar
equipment and unnecessary avionics
. A nitrogen
tank was installed for cabin pressurization
purposes, this was required as there would be no bleed air available from the engine after its normal and expected cutoff
in the climb phase.
Contrary to popular misconception, the jet engine was not allowed to flameout but had to be gradually throttled down and then cutoff as EGT temperatures ramped up towards the danger point for the turbojet's integrity.
AR2-3 rocket engine
was fitted at the base of the vertical fin. This engine burned a mixture of JP-4
jet fuel and 90% hydrogen peroxide
oxidizer solution. The NF-104 carried enough oxidizer for approximately 100 seconds of rocket engine operation. The thrust level could be adjusted to maximum or approximately half power by the pilot using an additional throttle lever on the left side of the cockpit
.
(RCS) consisted of eight pitch/yaw motors (four for each axis) and four roll motors. They used the same kind of hydrogen peroxide fuel as the main rocket engine from a dedicated 155 lbs fuel tank and were controlled by the pilot using a handle mounted in the instrument panel. The pitch/yaw motors were rated at 113 lbf (502.6 N) thrust each and the roll motors were rated at 43 lbf (191.3 N) thrust.
The NF-104A was able to reach great altitudes through a combination of zoom climbing (trading speed for altitude) and use of the rocket engine.
A typical mission involved a level acceleration at 35000 ft (10,668 m) to Mach
1.9 where the rocket engine would be ignited, and on reaching Mach 2.1 the aircraft would be pitched up to a climb angle of 50-70° by carefully applying a load equal to 3.5 g
. The J79 afterburner
would start to be throttled down at approximately 70000 ft (21,336 m) followed shortly after by manual fuel cutoff of the main jet engine itself around 85000 ft (25,908 m) to prevent fast rising engine temperatures from damaging the turbojet. After continuing over the top of its ballistic
arc the NF-104 would descend back into denser air where the main engine could be restarted using the windmill restart technique for recovery to a landing.
at Edwards Air Force Base
and can still be seen there today. The extended wing tips, RCS metal nose cone and other parts from 56-0760 were loaned to Daryl Greenamyer
for his civilian aviation record attempts using a highly modified F-104. When he was forced to eject during a record flight, his aircraft was destroyed and the parts were never returned.
and the film of the same name; although the aircraft used for filming was a standard F-104G flying with its wingtip fuel tanks removed, but otherwise lacking any of the NF-104A's modifications, most visibly the rocket engine pod at the base of the vertical stabilizer.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
mixed power, high-performance, supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
aerospace
Aerospace
Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...
trainer
Trainer (aircraft)
A trainer is a class of aircraft designed specifically to facilitate in-flight training of pilots and aircrews. The use of a dedicated trainer aircraft with additional safety features—such as tandem flight controls, forgiving flight characteristics and a simplified cockpit arrangement—allows...
that served as a low cost astronaut
Astronaut
An astronaut or cosmonaut is a person trained by a human spaceflight program to command, pilot, or serve as a crew member of a spacecraft....
training vehicle for the X-15 and projected X-20 Dyna-Soar
X-20 Dyna-Soar
The X-20 Dyna-Soar was a United States Air Force program to develop a spaceplane that could be used for a variety of military missions, including reconnaissance, bombing, space rescue, satellite maintenance, and sabotage of enemy satellites...
programs.
Three aircraft were modified from existing Lockheed F-104A
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...
airframes and served with the Aerospace Research Pilots School
U.S. Air Force Test Pilot School
The U.S. Air Force Test Pilot School is the Air Force's very advanced flight training school that trains experimental test pilots, flight test engineers, and flight test navigators to carry out tests and evaluations of new aerospace weapon systems and also other aircraft of the U.S. Air Force...
between 1963 and 1971, the modifications included a small supplementary 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...
and a reaction control system
Reaction control system
A reaction control system is a subsystem of a spacecraft whose purpose is attitude control and steering by the use of thrusters. An RCS system is capable of providing small amounts of thrust in any desired direction or combination of directions. An RCS is also capable of providing torque to allow...
for flight in the upper atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
. During the test program the maximum altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
reached was over 120,000 ft (36,600 m). One of the aircraft was destroyed in an accident while being flown by Chuck Yeager
Chuck Yeager
Charles Elwood "Chuck" Yeager is a retired major general in the United States Air Force and noted test pilot. He was the first pilot to travel faster than sound...
. The accident was depicted in the book The Right Stuff
The Right Stuff (book)
The Right Stuff is a 1979 book by Tom Wolfe about the pilots engaged in U.S. postwar experiments with experimental rocket-powered, high-speed aircraft as well as documenting the stories of the first Project Mercury astronauts selected for the NASA space program...
and the film of the same name.
Development
With the advent of manned spaceflight in the early 1960s, the United States Air ForceUnited States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...
Experimental Flight Test Pilot's School at Edwards Air Force Base
Edwards Air Force Base
Edwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond.It is named in...
was renamed the Aerospace Research Pilots School
U.S. Air Force Test Pilot School
The U.S. Air Force Test Pilot School is the Air Force's very advanced flight training school that trains experimental test pilots, flight test engineers, and flight test navigators to carry out tests and evaluations of new aerospace weapon systems and also other aircraft of the U.S. Air Force...
(ARPS), with the emphasis on training moving away from the traditional test pilot course to a more spaceflight oriented curriculum.
Initial use of unmodified F-104 aircraft
A number of standard production F-104 Starfighters were obtained (including F-104D two-seat versions) and used by the ARPS to simulate the low lift/high drag glide approach path profiles of the X-15 and the projected X-20 Dyna-SoarX-20 Dyna-Soar
The X-20 Dyna-Soar was a United States Air Force program to develop a spaceplane that could be used for a variety of military missions, including reconnaissance, bombing, space rescue, satellite maintenance, and sabotage of enemy satellites...
program. These maneuvers were commenced at 12000 ft (3,657.6 m) where the F-104 engine was throttled back to 80% power; and with the flaps, speedbrakes and landing gear extended, the aircraft was established in a 30˚ dive with a pull-out for the landing flare starting at 1500 ft (457.2 m) above the ground. These glide approaches gave little room for error.
A modified Gulfstream G-II
Shuttle Training Aircraft
The Shuttle Training Aircraft is a NASA training vehicle that duplicates the Space Shuttle's approach profile and handling qualities, allowing Space Shuttle pilots to simulate Shuttle landings under controlled conditions before attempting the task on board the orbiter.-Development:The aircraft's...
has been used by NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
for similar training for the Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
program.
Reaction Control System
Stratosphere
The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...
and that any aircraft operating at extremely high altitudes would need to be equipped with a reaction control system
Reaction control system
A reaction control system is a subsystem of a spacecraft whose purpose is attitude control and steering by the use of thrusters. An RCS system is capable of providing small amounts of thrust in any desired direction or combination of directions. An RCS is also capable of providing torque to allow...
(RCS). A modified version of the Bell X-1
Bell X-1
The Bell X-1, originally designated XS-1, was a joint NACA-U.S. Army/US Air Force supersonic research project built by Bell Aircraft. Conceived in 1944 and designed and built over 1945, it eventually reached nearly 1,000 mph in 1948...
was used for initial RCS tests, but was grounded after technical problems and was replaced with a NASA-modified Lockheed F-104A (55-2961) in 1959 which carried RCS systems on its wing tips and in the fuselage nose. This aircraft (designated JF-104) achieved a maximum altitude of 83000 ft (25,298.4 m) during the test program. Pilots who flew this aircraft included Neil Armstrong
Neil Armstrong
Neil Alden Armstrong is an American former astronaut, test pilot, aerospace engineer, university professor, United States Naval Aviator, and the first person to set foot upon the Moon....
who gained valuable experience in using the RCS system.
Pilots complained that the instrument displays were difficult to read and were not accurate enough for the critical zoom climb profiles required to reach high altitudes.
Lockheed contract
LockheedLockheed Corporation
The Lockheed Corporation was an American aerospace company. Lockheed was founded in 1912 and later merged with Martin Marietta to form Lockheed Martin in 1995.-Origins:...
was awarded a contract by the USAF to modify three F-104A aircraft for the dedicated role of aerospace trainer (AST) in 1962. The airframes were taken out of storage at AMARC and transported to the company factory for modification.
Design and flight profile
The F-104A design was already established as a lightweight, high performance aircraft; but for the AST project, emphasis was placed on removing unnecessary equipment, fitting a rocket engine to supplement the existing jet engine, fitting an onboard RCS system and improving the instrumentation required. The following details give the main differences between the production version and the AST:Wing
The wingspanWingspan
The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
of the NF-104A was increased by adding tip extensions to the existing planform
Planform
In aviation, a planform is the shape and layout of a fixed-wing aircraft's fuselage and wing. Of all the myriad planforms used, they can typically be grouped into those used for low-speed flight, found on general aviation aircraft, and those used for high-speed flight, found on many military...
. This modification was needed to house the RCS roll control thrusters and would also decrease the type's wing loading
Wing loading
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing. The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading. Correspondingly,...
.
Tail surfaces
The vertical fin and rudder were replaced by the larger area versions from the two-seat F-104 and were structurally modified to allow installation of the rocket engine.Fuselage
The fiberglassFiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
nose radome was replaced with an aluminum skin and housed the pitch and yaw RCS thrusters.
The air intakes originally designed by Ben Rich
Ben Rich
Benjamin Robert Rich was the second director of Lockheed's Skunk Works from 1975 to 1991, succeeding its founder, Kelly Johnson. Regarded as the "father of stealth," Ben Rich was responsible for leading the development of the F-117, the first production stealth aircraft...
were of the same fixed geometry as the F-104A but included extensions to the inlet shock cones for optimum jet engine operation at higher Mach number
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...
s.
Internal fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
differences included provision for rocket fuel oxidizer tanks, deletion of the M61 Vulcan
M61 Vulcan
The M61 Vulcan is a hydraulically or pneumatically driven, six-barreled, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm rounds at an extremely high rate. The M61 and its derivatives have been the principal cannon armament of United States military fixed-wing aircraft...
cannon, Radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
equipment and unnecessary avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
. A nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
tank was installed for cabin pressurization
Cabin pressurization
Cabin pressurization is the pumping of compressed air into an aircraft cabin to maintain a safe and comfortable environment for crew and passengers when flying at altitude.-Need for cabin pressurization:...
purposes, this was required as there would be no bleed air available from the engine after its normal and expected cutoff
Cutoff
In theoretical physics, cutoff is an arbitrary maximal or minimal value of energy, momentum, or length, used in order that objects with larger or smaller values than these physical quantities are ignored in some calculation...
in the climb phase.
Contrary to popular misconception, the jet engine was not allowed to flameout but had to be gradually throttled down and then cutoff as EGT temperatures ramped up towards the danger point for the turbojet's integrity.
Rocket engine
In addition to the standard J79 jet engine a RocketdyneRocketdyne
Rocketdyne was a Rocket engine design and production company headquartered in Canoga Park, California, United States. The company was related to North American Aviation for most of its history. NAA merged with Rockwell International, which was then bought by Boeing in December, 1996...
AR2-3 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 fitted at the base of the vertical fin. This engine burned a mixture of JP-4
JP-4
JP-4, or JP4 was a jet fuel, specified in 1951 by the U.S. government . It was a 50-50 kerosene-gasoline blend. It has lower flash point than JP-1, but was preferred because of its greater availability. It was the primary U.S. Air Force jet fuel between 1951 and 1995. Its NATO code is F-40...
jet fuel and 90% hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...
oxidizer solution. The NF-104 carried enough oxidizer for approximately 100 seconds of rocket engine operation. The thrust level could be adjusted to maximum or approximately half power by the pilot using an additional throttle lever on the left side of the cockpit
Cockpit
A cockpit or flight deck is the area, usually near the front of an aircraft, from which a pilot controls the aircraft. Most modern cockpits are enclosed, except on some small aircraft, and cockpits on large airliners are also physically separated from the cabin...
.
Reaction Control System
The Reaction Control SystemReaction control system
A reaction control system is a subsystem of a spacecraft whose purpose is attitude control and steering by the use of thrusters. An RCS system is capable of providing small amounts of thrust in any desired direction or combination of directions. An RCS is also capable of providing torque to allow...
(RCS) consisted of eight pitch/yaw motors (four for each axis) and four roll motors. They used the same kind of hydrogen peroxide fuel as the main rocket engine from a dedicated 155 lbs fuel tank and were controlled by the pilot using a handle mounted in the instrument panel. The pitch/yaw motors were rated at 113 lbf (502.6 N) thrust each and the roll motors were rated at 43 lbf (191.3 N) thrust.
Typical flight profile
A typical mission involved a level acceleration at 35000 ft (10,668 m) 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...
1.9 where the rocket engine would be ignited, and on reaching Mach 2.1 the aircraft would be pitched up to a climb angle of 50-70° by carefully applying a load equal to 3.5 g
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
. The J79 afterburner
AfterBurner
The AfterBurner is a lighting solution for the Game Boy Advance system that was created by Triton-Labs.Originally, portablemonopoly.net was a website created to petition Nintendo to put some kind of light in their Game Boy Advance system...
would start to be throttled down at approximately 70000 ft (21,336 m) followed shortly after by manual fuel cutoff of the main jet engine itself around 85000 ft (25,908 m) to prevent fast rising engine temperatures from damaging the turbojet. After continuing over the top of its ballistic
External ballistics
External ballistics is the part of the science of ballistics that deals with the behaviour of a non-powered projectile in flight. External ballistics is frequently associated with firearms, and deals with the behaviour of the bullet after it exits the barrel and before it hits the target.-Forces...
arc the NF-104 would descend back into denser air where the main engine could be restarted using the windmill restart technique for recovery to a landing.
First NF-104A
The first NF-104A (USAF 56-0756) was accepted by the USAF on 1 October 1963. It quickly established a new unofficial altitude record of 118860 ft (36,228.5 m) and surpassed this on 6 December 1963 by achieving an altitude of 120800 ft (36,819.8 m). It suffered an inflight rocket motor explosion in June 1971. Although the pilot was able to land safely, the damaged aircraft was retired and marked the end of the NF-104 project. This aircraft was reported as scrapped.Second NF-104A
The second NF-104A (USAF 56-0760) was accepted by the USAF on 26 October 1963. After retirement, this aircraft was mounted on a pole outside the U.S. Air Force Test Pilot SchoolU.S. Air Force Test Pilot School
The U.S. Air Force Test Pilot School is the Air Force's very advanced flight training school that trains experimental test pilots, flight test engineers, and flight test navigators to carry out tests and evaluations of new aerospace weapon systems and also other aircraft of the U.S. Air Force...
at Edwards Air Force Base
Edwards Air Force Base
Edwards Air Force Base is a United States Air Force base located on the border of Kern County, Los Angeles County, and San Bernardino County, California, in the Antelope Valley. It is southwest of the central business district of North Edwards, California and due east of Rosamond.It is named in...
and can still be seen there today. The extended wing tips, RCS metal nose cone and other parts from 56-0760 were loaned to Daryl Greenamyer
Daryl Greenamyer
Darryl Greenamyer is an American aviator. He started his flying career in the US Air Force Reserve. After leaving the Air Force, he then began to work at Lockheed where he eventually became an SR-71 test pilot at Skunk works. While working at Lockheed he met many of the engineers who would later...
for his civilian aviation record attempts using a highly modified F-104. When he was forced to eject during a record flight, his aircraft was destroyed and the parts were never returned.
Third NF-104A
The third NF-104A (USAF 56-0762) was delivered to the USAF on 1 November 1963, and was destroyed in a crash while being piloted by Chuck Yeager on 10 December 1963. This accident was depicted in the book The Right StuffThe Right Stuff (book)
The Right Stuff is a 1979 book by Tom Wolfe about the pilots engaged in U.S. postwar experiments with experimental rocket-powered, high-speed aircraft as well as documenting the stories of the first Project Mercury astronauts selected for the NASA space program...
and the film of the same name; although the aircraft used for filming was a standard F-104G flying with its wingtip fuel tanks removed, but otherwise lacking any of the NF-104A's modifications, most visibly the rocket engine pod at the base of the vertical stabilizer.
Specifications (NF-104A)