JP-5 (Jet Propellant 5) is a high-flashpoint, kerosene-based jet fuel used primarily by the United States Navy and other naval forces for aircraft operating on aircraft carriers.
Its defining characteristic is safety; because ships are confined spaces with high fire risks, JP-5 is engineered to be much harder to ignite accidentally than standard jet fuels.
## Key Specifications & Properties
JP-5 is a complex mixture of hydrocarbons with strict physical requirements:
| Property | Value / Specification |
| Flash Point | 60°C (140°F) minimum |
| Freezing Point | -46°C (-51°F) maximum |
| Density (at 15°C) | 0.788 – 0.845 kg/L |
| Auto-ignition Temp | ~246°C (475°F) |
| NATO Code | F-44 |
| Military Spec | MIL-DTL-5624 |
### Why the High Flash Point?
Standard commercial jet fuel (Jet A) and the Air Force’s primary fuel (JP-8) have a minimum flash point of roughly 38°C (100°F).
- Safety on Ships: On an aircraft carrier, fuel is stored in tanks near ammunition and living quarters. The higher flash point of JP-5 (60°C) ensures that the fuel will not produce enough flammable vapor to ignite at normal room temperatures, significantly reducing the risk of a catastrophic fire if a tank is pierced or a leak occurs.
- Cost: Because it requires more intensive refining to remove the more volatile, low-flashpoint components, JP-5 is more expensive to produce than JP-8 or Jet A.
### Composition & Additives
JP-5 is highly refined kerosene containing approximately:
- Paraffins: 53%
- Cycloparaffins (Naphthenes): 31%
- Aromatics: 16% (max 25% by spec)
- Olefins: 0.5%
It also includes a specific “additive package” to ensure performance:
- Fuel System Icing Inhibitor (FSII): Prevents ice crystals from forming in fuel lines at high altitudes.
- Corrosion Inhibitors: Protects the engine and fuel system from moisture.
- Antioxidants: Prevents the formation of “gum” or deposits during long-term storage.
- Static Dissipators: Reduces the risk of sparks during high-speed refueling.
### Comparison: JP-5 vs. JP-8
While both are kerosene-based, they are not always interchangeable due to the Navy’s strict fire safety requirements:
- JP-8 (F-34): The “Universal” NATO land-based fuel. Easier to ignite and cheaper to make.
- JP-5 (F-44): The “Sea-based” fuel. Harder to ignite, safer for shipboard storage.
- Note: Navy aircraft can usually run on JP-8 if necessary (e.g., when landing at an Air Force base), but JP-8 is generally forbidden from being stored in the main deep-storage tanks of aircraft carriers.
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