Quick Spin Knuckle

Quick Spin Knuckle (アクセルスピンナックル), also known as the Axel Spin Knuckle, is one of Cammy's special attacks, introduced in Super Street Fighter II: The New Challengers. The move is also part of Juli's arsenal in Street Fighter Alpha 3. In Street Fighter V, it is her V-Skill.

Description
Cammy approaches her opponent by hopping into the air and spinning her back around to the opponent before whipping her fist a full 360°. If she connects with this move up close, she can hit twice - first with her elbow, and next with her fist (via her standing heavy punch animation). In the Marvel vs. Capcom crossovers, Cammy engulfs her fist with Psycho Power.

Tactics
While performing this move, the user will evade most attacks, save for ones that connect with her head; however, it typically has a lengthy startup time. Quick Spin Knuckle can also go through fireballs and be canceled with the Spin Drive Smasher in Street Fighter IV (in which is also her Armor Break).

Street Fighter X Tekken
Quick Spin Knuckle is one of Cammy's safest Switch Cancel attacks in terms of time for partner to come in, as Cannon Drill's first hit only connects at point blank range and the second hit alone isn't enough to keep the opponent in enough blockstun for her partner to protect Cammy in time. using QSK in this fashion can be risky due to invincibility running out before the attack comes out.

The EX Version does even more blockstun, has a faster startup, and wall bounces her opponent on hit, making it a better option at the cost of two meter. This version also runs out of invincibility before the attack comes out however.

Street Fighter V
Axel Spin Knuckle is much more vital to her offensive game due to the new ability to be able to cross-up her opponent with the forward leap. Similar to previous games, Cammy can use this move to spin through fireballs, while following up with her attack as the opponent is recovering, leading to some decent combos for a good amount of damage.

Trivia

 * This attack has had different inputs in every main series game it appears in.