Immelmann turn

This article is about aerial maneuvers. For the roller coaster element, see Immelmann loop.

The Immelmann turn refers to two different aircraft maneuvers:

• In World War I aerial combat, an Immelmann turn was a maneuver used after an attack on another aircraft to re-position the attacking aircraft to dive back down to re-attack.
• In modern aerobatics, an Immelmann turn (also known as a roll-off-the-top, or simply an Immelmann) is an aerobatic maneuver that results in level flight in the opposite direction at a higher altitude.

Historical combat maneuver

Illustration of the historical maneuver from a 1918 flight manual

In World War I aerial combat, an Immelmann turn was a maneuver used after an attack on another aircraft to re-position the attacking aircraft to dive back down to re-attack.

After making a high speed diving attack on an enemy, the attacker would then climb back up past the enemy aircraft, and just short of the stall, apply full rudder to yaw his aircraft around. This put his aircraft facing down at the enemy aircraft, making another high speed diving pass possible. This is a difficult maneuver to perform properly, as it involves precise control of the aircraft at low speed. With practice and proper use of all of the fighter's controls, the maneuver could be used to re-position the attacking aircraft to dive back down in any direction desired. This form of "Immelmann turn" was called Renversement by French pilots.^{[citation needed]}

As a practical combat tactic, the Immelmann had already fallen somewhat into disfavor by 1917/1918, as it became obvious that the zooming aircraft presented an easy target as it hung nearly motionless at the top of the maneuver - provided the aircraft under attack was sufficiently powerful and well armed to follow his adversary, or was fitted with flexible forward and upward firing guns. In fact, its use in combat assumes an inferior opponent.^{[citation needed]}

Aerobatic maneuver

Schematic view of an Immelmann turn:
1. Level flight.
2. Half loop.
3. 180° roll to bring aircraft back level.

In modern aerobatics, an Immelmann turn (also known as a roll-off-the-top, or simply an Immelmann) is an aerobatic maneuver of little practical use in aerial combat. Essentially, the aerobatic Immelmann comprises an ascending half-loop followed by a half-roll, resulting in level flight in the exact opposite direction at a higher altitude.

The aerobatic Immelman turn derives its name from a different maneuver altogether - a dogfighting tactic of World War I named after the German pilot Max Immelmann.

To successfully execute the aerobatic Immelmann turn, the pilot accelerates to sufficient airspeed to perform a loop in the aircraft. The pilot then pulls the aircraft into a climb, and continues to pull back on the controls as the aircraft climbs. Rudder and ailerons must be used to keep the half-loop straight when viewed from the ground. As the aircraft passes over the point at which the climb was commenced, it should be inverted and a half loop will have been executed. Sufficient airspeed must be maintained to recover without losing altitude, and at the top of the loop the pilot then executes a half-roll to regain normal, upright aircraft orientation. As a result, the aircraft is now at a higher altitude and has changed course 180 degrees.

Not all aircraft are capable of (or certified for) this maneuver, due to insufficient engine power, or engine design that precludes flying inverted (usually piston engines that have an open oil pan). In fact, few early aircraft had sufficiently precise roll control to have performed this maneuver properly.^{[citation needed]}

The Immelmann turn has become one of the most popular aerobatic maneuvers, being commonly used in airshows all over the world. However, the aerobatic maneuver is of little use in modern dogfighting, because modern high thrust fighters can quickly initiate sustained vertical maneuvering from level flight, and slow targets are highly vulnerable to air-to-air missiles. The aerobatic maneuver also involves rapid "energy loss" (loss of airspeed) even if the nose is pushed down sharply as the maneuver is completed (This maneuver, an aerobatic Immelman followed by a dive back to the original altitude is another aerobatic maneuver called the "Half-Cuban-Eight").^{[citation needed]}

Sometimes called a "reverse" or "inverted" Immelmann is the Split S maneuver, which is a half-roll followed by a descending half-loop, resulting in level flight in the exact opposite direction at a lower altitude.^{[citation needed]}

See also

• Chandelle
• The Scissors

References

• The "Immelman" Turn