astronomy

Lockheed NF-104A

Lockheed NF-104A is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lockheed NF-104A rather than just read about it. In short: The Lockheed NF-104A is an American mixed-power, high-performance, supersonic aerospace trainer that served as a low-cost astronaut training vehicle for the North American X-15 and projected Boeing X-20 Dyna-Soar programs. Three aircraft were modified from existing Lockheed F-104A Starfighter airframes, and served with the Aerospace Research Pilots School between 1963 and 1971.

Key takeaways

Lockheed NF-104A belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Lockheed NF-104A to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lockheed NF-104A from memory before moving on to harder problems.

Reference excerpt

The Lockheed NF-104A is an American mixed-power, high-performance, supersonic aerospace trainer that served as a low-cost astronaut training vehicle for the North American X-15 and projected Boeing X-20 Dyna-Soar programs. Three aircraft were modified from existing Lockheed F-104A Starfighter 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 stratosphere. During the test program, the maximum altitude reached was more than 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 1983 film. On December 10, 2019, Edwards Air Force Base released the complete video transcription of films of the 1963 flight and subsequent crash.

Development With the advent of human spaceflight in the early 1960s, the United States Air Force (USAF) 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.

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-Soar program. These maneuvers were commenced at 12,000 ft (3,700 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 1,500 feet (500 m) above the ground. These glide approaches gave little room for error.

Reaction control system

It was realized that normal aircraft control surfaces had little or no effect in the thin air of the upper 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. It was replaced in 1959 with a NASA-modified Lockheed F-104A (55-2961), which carried RCS systems on its wing tips and in the fuselage nose. This aircraft (designated JF-104) achieved a maximum altitude of 83,000 feet (25,300 m) during the test program. Pilots who flew this aircraft included Neil Armstrong, who gained valuable experience in using the RCS. 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 Lockheed was awarded a contract by the United States Air Force to modify three F-104A aircraft for the dedicated role of aerospace trainer (AST) in 1962. The airframes were taken out of storage at AMARG 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. 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, and improving the instrumentation. The following are the main differences between the production version and the AST:

Wing The wingspan of the NF-104A was increased by the addition of wingtip extensions. This modification was needed to house the RCS roll control thrusters and decreased the wing loading.

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 fiberglass 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 cones for optimal jet engine operation at higher Mach numbers. Internal fuselage differences included provision for rocket propellant oxidizer tanks and removal 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.

Rocket engine

In addition to the standard General Electric J79 jet engine, a Rocketdyne 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.

Reaction control system The reaction control system consisted of eight pitch/yaw thrusters (four for each axis) and four roll thrusters. They used the same kind of hydrogen peroxide fuel as the main rocket engine from a dedicated 155 lb (70 kg) fuel tank and were controlled by the pilot using a handle mounted in the instrument panel. The pitch/yaw thrusters were rated at 113 lbf (500 N) thrust each and the roll thrusters were rated at 43 lbf (190 N) thrust.

Typical flight profile

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Lockheed NF-104A

Start with the simplest possible case. Write down what Lockheed NF-104A claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lockheed NF-104A before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lockheed NF-104A ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lockheed NF-104A

In research: Lockheed NF-104A appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Lockheed NF-104A in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Lockheed NF-104A is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1950s United States experimental aircraft, 1950s United States military trainer aircraft, Aircraft first flown in 1963, so understanding it makes those chapters shorter.
In everyday life: Look for Lockheed NF-104A outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Lockheed NF-104A in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lockheed NF-104A means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Lockheed NF-104A out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lockheed NF-104A in simple terms?

Why does Lockheed NF-104A matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lockheed NF-104A?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lockheed NF-104A.