Radius of action, combat radius, or combat range in military terms, refers to the maximum distance a ship, aircraft, or vehicle can travel away from its base along a given course with normal load and return without refueling, allowing for all safety and operating factors.
A given aircraft's
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
of action varies according to the
altitude
Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...
of its
flight plan, amount of weight (
ordnance
Ordnance may refer to:
Military and defense
*Materiel in military logistics, including weapons, ammunition, vehicles, and maintenance tools and equipment.
**The military branch responsible for supplying and developing these items, e.g., the Unit ...
in a military context) it is carrying, and whether or not it carries external
drop tanks
In aviation, a drop tank (external tank, wing tank or belly tank) is used to describe auxiliary fuel tanks externally carried by aircraft. A drop tank is expendable and often capable of being jettisoned. External tanks are commonplace on modern ...
full of fuel.
*An aircraft engaged in ''
low-level (lo)'' flight will have a smaller radius of action than the same one engaged in a ''high-level (hi)'' mission, due to higher
fuel consumption
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but ...
at lower altitudes (higher
atmospheric pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, ...
/
air density).
*An aircraft with more and heavier load (''ordnance'' in military terms) will have a smaller radius of action (''combat radius'' in military terms) than the same one with less and lighter load, due to higher fuel consumption at heavier weights.
*An aircraft with
drop tank
In aviation, a drop tank (external tank, wing tank or belly tank) is used to describe auxiliary fuel tanks externally carried by aircraft. A drop tank is expendable and often capable of being jettisoned. External tanks are commonplace on modern ...
s will have a greater radius of action than the same one without.
In military aviation, the combat radius of an aircraft is often given with its mission profile (without
in-air refueling). For example:
*The
F-16 Fighting Falcon's combat radius is 550 km (340 mi) on a ''hi-lo-hi'' mission with six 450 kg (1,000 lb) bombs.
*The
F/A-18 Hornet has a combat radius of 537 km (330 mi) on a ''hi-lo-lo-hi'' mission.
The radius of action of an aircraft is always smaller than its
maximum range (a. k. a. combat range), the furthest distance the aircraft can fly with maximum payload and without refueling, or
ferry range
The maximal total range is the maximum distance an aircraft can fly between takeoff and landing. Powered aircraft range is limited by the aviation fuel energy storage capacity (chemical or electrical) considering both weight and volume limits. U ...
, the furthest distance the aircraft can fly with drop tanks, no load or ordnance and without refueling. The rule of thumb is that the radius of action is one-third the distance an aircraft can fly in a straight line on a full load of fuel. In military aviation, this assumes a trip out and back, plus one-third of fuel for combat operations.
See also
*
Range (aeronautics)
References
Military aviation
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