Fatman, nahnahnahnah~

(IW) The YSF4H-1 on its first successful boosted jump.

The Jump Unit is a hybrid propulsion system for any Tactical Surface Fighter. As one of the core equipment sets of a TSF, the advantages that Jump Units provide are near-limitless. A Jump Unit contains a hybrid jet-and-rocket engine system; the jet engine components having greater fuel economy during flight, and the rocket engine components allowing it to quickly output high-powered thrust for rapid maneuvering.[1]


Thrust concept

(IW) The primary operating modes of a typical Jump Unit hybrid engine.

The Jump Unit, in actuality, refers to the twin booster components that are (usually) attached to the TSF's rear; depending on model, either to the waist block or the rear upper thigh. Jump Units of all model and make fulfill similar functions; most contain a hybrid engine, are mounted to a TSF via a sub-arm that can be operated independently, giving it thrust vectoring capabilities,[1] are capable of reverse thrust,[2] and can be purged from the TSF in the event of an emergency.[1] However, some Jump Units may have other functions that are unique to their model.

During operation, the Jump Unit engine operates in either jet or rocket mode, but never both at once. In jet engine mode, the engine operates like any other turbofan jet engine.[3] The Jump Unit switches to rocket engine mode during instances where high maneuverability or high output thrust is required. While the rocket engine is active, the jet components of the engine continues to operate on idle rather than completely shutting down.[4]



(IW) The Type-91 Jump Unit used by Imperial Japanese forces, here seen mounted on a Type-94 Shiranui.

Similar to the F-4 Phantom TSF itself, the Jump Unit's origins lie with the NCAF-X1 prototype, which was equipped with rocket boosters built to work in the airless conditions of space. This was carried over into the NCSF-X program, and eventually the YSF4H-1 prototype what would become the F-4. Early Jump Units were fixed in the position in which they were mounted, but later models allow the Jump Unit to swivel on its mountings using sub-arms, allowing TSFs to perform thrust-vectoring maneuvers.

It should be noted that "Jump Unit" refers to the component as a whole, while "engine" refers to the model of fuel-burning propulsion device housed within. For example, both the Shiranui and Takemikazuchi use the same Japanese-made Type-91 Jump Unit, but the Shiranui's Jump Units use FE108-FHI-220 engines while the Takemikazuchi's Jump Units use FE108-FHI-223, FE108-FHI-225, and FE108-FHI-227 engines.



An F-16C's Jump Unit undergoing an overload reaction.

The Jump Unit has, over the years, become an integral part of a Tactical Surface Fighter's combat loadout. It is the means to which a TSF can execute a majority of its combat maneuvers; from a simple boost jump over an obstacle to life-saving evasive maneuvers in the heat of battle and even prolonged flight back to the safety of a military base, the Jump Unit is indispensable.

Most 3rd generation Jump Units have aerodynamic surfaces constructed with sharpened Super Carbon for greater anti-Tank defences during high-speed combat, and also to improve the Jump Unit's durability. It is also possible to use a Jump Unit as a suicidal attack by overloading its engines to cause an explosion.


With the passing of time, there have been improvements and offshoot technologies from the standards set down by earlier Jump Units.

Variable Wing MechanismEdit

A mechanism that allows the wings on a Jump Unit to change their vertical angle positioning; commonly used to boost the maneuverability of the TSF at the expense of increased operating costs of varying degrees. Examples of TSF equipped with Jump Units that have this function include the F-14, the MiG-23/MiG-27, and the Tornado-series.

Optional ThrustersEdit

Additional thrust-producing engines that can be attached or built into a TSF, distinct from the Jump Units that all TSFs have. They do not produce enough thrust for lift, but are instead used as maneuverability multipliers; by mounting them on a TSF's back, shoulder, waist or torso block, they can be used to push a TSF in a given direction in an emergency maneuver, or increase their speed in combat. TSFs noted to have this function include the Su-37-series, F-15ACTV, and Type-04.

Engine ModelsEdit

While TSFs related in development may share Jump Unit designs, the engines that they use within are different and can vary from improved models of a previous engine type to a completely different engine from a different manufacturer.

For a comprehensive list, refer to the Jump Unit Engine List.

See AlsoEdit


  • The Type-94, Type-97, Type-00, and Type-04 are the only TSFs that are not direct variants of each other to use the same Jump Unit.
  • The variable-sweep wing mechanism in the real world does not appear on the F-14, MiG-23/-27 and Tornado-series; the same mechanism in Muv-Luv changes the wing's vertical angle, as opposed to its horizontal sweep angle. In this aspect, its function is closer to modern aileron and/or elevator systems.
  • Most Jump Units bear a slight to moderate resemblance of the aircraft that their TSFs are based upon.



  1. 1.0 1.1 1.2 Integral Works, pg. 47, 噴射跳躍システム
  2. Integral Works, pg. 47, 推力制御の概念図
  3. Integral Works, pg. 47, ジェットエンジン燃焼時
  4. Integral Works, pg. 47, ロケットエンジン燃焼時