Fighter Combat

414 APPENDIXFigure A-20. Variations in Roll Rate with AirspeedIn air combat, continuous rolls of more than 180° are seldom required.Because a certain length of time is necessary to accelerate the roll rate fromzero to its maximum value, maximum stabilized roll rate may not bereached during such short periods of roll. Therefore, roll acceleration isoften the controlling factor in combat performance.In addition to roll-control power, roll acceleration is a function of the"moment of inertia" of the aircraft. This moment of inertia about the rollaxis depends on the aircraft weight and its distribution. The greaterthe total weight, and the farther it is distributed away from the fuselageaxis, the greater the inertia. Large wingspan, tip-tank fuel, and wingmountedordnance or engines, for example, would contribute to increasedroll inertia and reduced roll acceleration. In addition, roll performance mayvary between left and right depending on the design of the aircraft. Propdrivenfighters, for instance, generally have better roll acceleration in thedirection opposite to that of prop rotation because of engine torque effects.Cockpit configuration may also be a factor, particularly with unboostedcontrol systems at high speeds. The pilot's ability to push the stick to theleft harder than he can pull it to the right may result in a noticeabledifference in roll performance.Stabilized roll rate is also affected by wingspan. For geometrically similarfighters, shorter wingspan results in higher stabilized roll rate for thesame speed and control deflection.Roll performance is highly dependent on pilot technique as well as on