JP-8

Key takeaways

JP-8 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect JP-8 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of JP-8 from memory before moving on to harder problems.

Reference excerpt

JP-8, or JP8 (for "Jet Propellant 8"), is a jet fuel, specified and used widely by the US military. It is specified by MIL-DTL-83133 and British Defence Standard 91-87, and similar to commercial aviation's Jet A-1, but with the addition of corrosion inhibitor and anti-icing additives. It was first introduced at NATO bases in 1978. Its NATO code is F-34.

Usage The United States Air Force replaced JP-4 with JP-8 completely by the end of 1995, to use a less flammable, less hazardous fuel for better safety and combat survivability. In 2014, they completed the process of converting all JP-8 installations within the continental United States to instead use commercial Jet A-1 fuel with additional additives. Installations in Alaska still utilize JP-8 in place of Jet A-1 because of its better suitability in cold weather environments. JP-8 is formulated with an icing inhibitor, corrosion inhibitor–lubricants, and antistatic agents, and contains less benzene (a carcinogen) and n-hexane (a neurotoxin) than JP-4. However, it also smells stronger than JP-4. JP-8 has an oily feel to the touch, while JP-4 feels more like a solvent. The United States Navy uses a similar formula, JP-5. JP-5 has an even higher flash point of > 140 °F (60 °C), but also a higher cost. The U.S. Navy Seabees use JP-8 in construction and tactical equipment.

Single-fuel concept JP-8 was specified in 1990 by the U.S. government as a replacement for government diesel fueled vehicles. This is in the wider context of the 1986 NATO Single-Fuel Concept agreement, in which F-34 (JP-8) is to replace F-54 (diesel fuel) in land vehicles and F-40 (JP-4) in land-based turbine aircraft to simplify logistics. It is also used as coolant in engines and some other aircraft components. Beyond use in vehicles from trucks to tanks to planes, JP-8 is used in U.S. Army heaters and stoves.

Problems

Diesel problems When used in highly turbocharged diesel engines with the corresponding low compression ratio (e.g. 14:1 or lower), JP-8 causes troubles during cold start and idling due to low compression temperatures and subsequent ignition delay because the cetane index is not specified in MIL-DTL-83133G to 40 or higher. Because lubricity to the BOCLE method is not specified in MIL-DTL-83133G, modern common-rail diesel engines can experience wear problems in high-pressure fuel pumps and injectors. Another problem in diesel engines can be increased wear to exhaust valve seats in the cylinder heads, because a maximum sulfur content is not specified in MIL-DTL-83133G. Sulfur in fuel normally contributes to a build-up of soot layers on these valve seats. According to the notes in this standard, it is intended to include a cetane index value in one of the next releases. MIL-DTL-83133J sets the maximum sulfur content at 0.30%. It however only requires a cetane number of 40 after addition of FT-SPK (synthetic jet fuel). The use of jet fuel in diesel engines has caused some minor issues, none of which were discovered in the Fort Bliss test with JP-8. During Desert Shield and Desert Storm, commercial Jet A1 was used as the single-fuel and failed engines with Stanadyne fuel-injection pumps missing an elastomer insert retrofit. Other than that, JP-8 slightly reduces torque and fuel economy due to its lower density and viscosity compared to diesel fuel. Engine modification can offset this issue.

Health concerns Workers have complained of smelling and tasting JP-8 for hours after exposure. As JP-8 is less volatile than standard diesel fuel, it remains on the contaminated surfaces for longer time, increasing the risk of exposure. In 2001, Texas Tech University's Institute of Environmental and Human Health and the United States Air Force conducted an 18-month study of the health effects of JP-8 on 339 active duty personnel at six US Air Force installations. The study found that Air Force workers who were exposed to JP-8 were no more likely to seek medical attention than workers who were not exposed to JP-8 on the job.

Variants JP-8+100 (F-37) is a variant of JP-8 augmented with the additive Spec-Aid 8Q462, also known as Aeroshell Performance Additive 101, created by BetzDearborn (now GE Betz). The additive increases the thermal stability of JP-8 by 100°F (56°C), hence the designation "+100". Spec-Aid 8Q462 was introduced in 1994 to reduce choking and fouling in engine fuel systems and is a combination of a surfactant, metal deactivator, and an antioxidant. It is added to JP-8 at a ratio of 256 ppm to create JP-8+100, at an added cost of $5 per 1000 gallons of fuel. Commercially, this additive is used in police helicopters in Tampa, Florida. JP-8+100 is also used for Canadian Forces CP-140 Aurora, CC-130 Hercules, CF-18 Hornet and the CC-115 Buffalo. F-35 is a variant without icing inhibitor. The only required additive is a static dissipater. JP-8+100LT is a variant of JP-8+100, with additives to facilitate low-temperature performance. It is considered as a logistically friendly low-cost replacement of the JPTS fuel for the Lockheed U-2 airplane. F-24 is commercial Jet A fuel (ASTM D1655) with the additive package required for JP-8 (SDA, CI/LI, FSII) added by the military. The intention is to lower costs by using commercially available fuel. The resulting fuel has identical properties to JP-8, save for a higher freezing-point specification. The U.S. military has switched to F-24 in domestic (excluding Alaska) sites in 2012. In 2018, it was found that the F-24 mixture could deteriorate during transport causing much reduced thermal stability, but addition of the +100 (8Q462) additive was enough to salvage degraded fuel. F-27 is F-24 with the +100 additive package. JP-8+225 is a planned variant of JP-8 that increases thermal stability by 225 °F (125 °C). Such a fuel would match the thermal stability of JP-7 and become a lower-cost replacement should it exist.

See also Aviation fuel JP-6 JP-7 JP-10 JPTS

References

External links MIL-DTL-83133 technical specifications (includes JP-8) United States Defense Energy Support Center MIL-DTL-46162 referee fuel Diesel and JP-8 United States Defense Energy Support Center Current United States Department of Defense Fuel Prices JP-8 Material Safety Data Sheet Archived 2019-12-26 at the Wayback Machine from Shell US Gas and Power

Worked examples

Example 1 — a first encounter with JP-8

Start with the simplest possible case. Write down what JP-8 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 JP-8 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 JP-8 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 JP-8

In research: JP-8 appears in science 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 JP-8 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: JP-8 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1990 introductions, Aviation fuels, so understanding it makes those chapters shorter.
In everyday life: Look for JP-8 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.

How to study JP-8 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what JP-8 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 JP-8 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is JP-8 in simple terms?

JP-8, or JP8 (for "Jet Propellant 8"), is a jet fuel, specified and used widely by the US military. It is specified by MIL-DTL-83133 and British Defence Standard 91-87, and similar to commercial aviation's Jet A-1, but with the addition of corrosion inhibitor and anti-icing additives.

Why does JP-8 matter?

Because it connects several science 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 JP-8?

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 JP-8.