"Clifford" Louie Yim-qun (Chinese: 雷炎均; Jyutping: leoi4 jim4 gwan1; pinyin: Léi Yánjūn; Taishanese: lui3 yiam5 gun1; 1914–1999), also known as Louie Yen-chung (Chinese: 燕中; pinyin: Yànzhōng), was a Chinese-American pilot and military officer in the Republic of China.

He became Deputy Commander of the 28th Fighter Squadron of the 5th Fighter Group in 1937, equipped with the Curtiss Hawk II, and first saw combat while stationed at Jurong Airbase in the Nanjing defense sector as the War of Resistance-World War II broke out,[1] and then transferring to the northern front of the war in China at the Battle of Taiyuan with Captain Chan Kee-Wong on September 16, 1937,[2] he shot down a Nakajima Ki-4 on September 18.

While the wartime capital of China was pushed back to Chongqing following the Fall of Wuhan, both sea and land routes for badly needed war supplies and high-octane aviation fuel were mostly cut off, especially after the loss of Nanning in the Battle of South Guangxi and increasing threat of the Japanese invasion of French Indochina, Major Louie Yim-qun's 28th Fighter Squadron, now equipped with Polikarpov I-15 fighters, has been reassigned with the defense of Sichuan.

On September 13, 1940, in what would be the introduction and first aerial combat engagement for the state-of-the-art new A6M "Zero" fighter, Maj. Louie led six I-15bis to join a formation 19 I-15bis and nine I-16s commanded by Major Cheng Hsiao-yu, Captain Yang Meng-ging and Captain Zhang Hong; they were engaged in a 1/2-hour long dogfight with 13 Zero fighters led by Lieutenant Saburo Shindo of the 12th Kokutai on an escort mission for 27 G3M "Nell" medium-heavy bombers on a raid against Chongqing.

His first wife, Hazel Ying Lee, was killed in a flying accident at Great Falls, Montana, on November 23, 1944, while ferrying a P-63 from Buffalo, New York.