Spoileron

In aeronautics spoilerons, also known as spoiler ailerons, are flight control surfaces, specifically spoilers that can be used asymmetrically to provide adequate roll control if aileron action would produce excessive wing twist on a very flexible wing or if wide-span flaps prevent adequate aileron roll control.

Spoilerons help to roll an aircraft by reducing the lift of one wing, but, unlike ailerons, not by increasing the lift of the other wing. As a side effect, a raised spoileron also increases the drag on one wing which causes the aircraft to yaw, which can be compensated with the rudder. Spoilerons can be used to assist the ailerons or replace them entirely, as in the B-52G which required an extra spoiler segment.

An early use of spoilers for augmenting small ailerons, known as guide ailerons, was in the Northrop P-61 Black Widow night fighter. The spoilers allowed wider-span flaps for a lower landing speed.

The B-52 Stratofortress also had spoilers augmenting small ailerons, known as feeler ailerons. These ailerons provided control forces to the pilot. The B-52G has no ailerons. The spoilers, situated inboard and forward of the trailing edge, are used for lateral control at high speeds to prevent excessive wing twist.

The Mitsubishi Mu-2 has double-slotted flaps that take-up the full length of the wing, leaving no room for ailerons. Like the B-52 it has spoilerons near the center of the wing.

The Mitsubishi Diamond Jet, Beechjet, and Hawker 400 family of business aircraft incorporate full length spoilerons that also double as speed spoilers during flight and landing.

Another aircraft with full-length double-slotted flaps was the Wren 460. To go with large aileron deflections at low speeds it had a set of 5 feathering drag plates ahead of each aileron to overcome adverse aileron yaw and decrease lift on the low wing.

Boeing's line of jet airliners and Tupolev Tu-154 have fast-acting spoilers. They double as spoilerons that assist the ailerons when the pilot commands a high roll rate. These can be readily seen in operation when the pilot is fighting gusting crosswinds when landing.

...
Wikipedia