Starshiy leytenant Opasov served as a volunteer in China.

During his time in China he flew both the Polikarpov I-16 and the I-15bis.

On 31 May, the Japanese executed a new attack on the aerodromes of fighters defending the Chinese capital. The Chinese had received advance information and were ready for them, having been able to concentrate aircraft at the Hankou aerodrome already the day before. In all, there were concentrated more than a hundred fighters.
At 10:15, 18 enemy bombers were spotted over Tung Chin by Chinese air defence lookouts followed by a reported 36 enemy aircraft over Lu-Jiang at 10:45. 46 enemy aircraft were spotted over the Camel Pass at 11:45 followed by a report of 39 enemy fighters near Qing-Shan at 12:00.
Thus, at midday a reported 39 enemy fighters and 18 enemy bombers approached Wuhan. At 11:50 49 Chinese interceptors successively began taking off from Wuhan. The Chinese fighters were four I-15bis from the 3rd PG, eight I-15bis and six I-16s (of the 21st PS) from the 4th PG, 21 I-15bis and ten I-16s from the Soviet volunteers. The 31 Soviet volunteers become the main attack force according to a previously devised plan while the 18 Chinese fighters climbed higher to provide an echeloned covering detachment. The fighters patrolled between Hankou and Qing-Shan.
Even before the appearance of the bombers, one of the groups of fighters flown by the Soviet volunteers was attacked at 12:07 by 18 A5Ms at 4500 meters. The Japanese fighter formation was reported to be 39 aircraft flying in a ‘V’ formation with 18 fighters at 4500 meters, 12 at 5000 meters and the high-cover of 9 fighters at 6000 meters. Six I-15bis flown by Soviet volunteers arrived to reinforce but at the same time 18 A5Ms joined the fight, leaving only 3 A5Ms as high-cover. At this them the I-16s from the 21st PS also joined the combat while the rest of the slower I-15bis gradually also did this. The formation led by Captain Cheng Hsiao-Yu, consisting of four I-15bis from the 3rd PG and eight I-15bis from the 4th PG didn’t manage to join combat since they were farthest away when the combat started and when they arrived north-east of the airport the enemy evaded east.
After the bombers appeared, A. Zingaev’s group threw themselves upon them, and with the first attack shot down two. The remaining bombers of the first group and the two remaining groups were not able to force their way through to the aerodrome and they turned back.
According to the recollections of N. G. Kozlov, the encounter with a large group of A5Ms occurred about 15 to 20 km east of the aerodrome. The Japanese attacked leaving one flight at altitude. Following the manoeuvres of his leader, Kozlov in a banking turn gave a burst at a Japanese fighter, which was following Opasov. In the turning carousel, this Japanese finally flew directly into the gun sights of Kozlov’s I-15bis, but the burst went into an already burning aircraft. A second Japanese began an attack on Kozlov. For their part, the I-16s conducted a battle in the vertical, diving at a steep angle and hitting the Japanese and then soaring upwards, and opening fire at the moment when the Japanese was dependent on his motor, climbing through a half loop. Mainly attacking out of the sun, the Japanese quickly lost the initiative, which gradually passed to the Chinese, as the battle dissolved into a sharp dogfight and gradually dissipated. While departing Kozlov let off a burst at long range at a Japanese under attack by two I-15bis, and the A5M limply began turning wing over wing and tumbled out of control to the ground.
In this combat Anton Gubenko returned in his damaged aircraft and reported that he had shot down one Japanese and rammed another. Aleksey Blagoveshchenskiy also claimed an enemy aircraft in this combat while Grigoriy Kravchenko claimed two.
Totally the Chinese fighters claimed 14 enemy aircraft shot down after a battle that lasted for 30 minutes. The 21st PS Squadron Leader, Captain Lo Ying-Teh, claimed one enemy aircraft shot down, which crashed south of Hou Lake. Lieutenant Liu Chi-Sheng of the 21st PS returned claiming an A5M, which crashed 20 kilometres north of the airfield. The pilot was seen to bale out. Han Sen teamed up with Huang Yan-Po and jointly they attacked one enemy aircraft five times before it crashed near Tian-Xin Shoal. The Soviet volunteers claimed six enemy aircraft shot down; one crashed at She-Kou, killing the pilot while another crashed 30 kilometres from She-Kou with the pilot parachuting.
The Chinese and the Soviet pilots each lost one pilot and one aircraft and several aircraft were seriously damaged. The 21st PS flight leader, Zhang Xiao-Xian, in I-16 no. 2107 was shot down and crashed in the Dai-Jia Mountain killing Zhang. I-15bis no. 90, flown by a Soviet volunteer, crashed near Hang-Dian but the pilot managed to parachute safely.
The Japanese record that 35 A5Ms (eleven from the 12th and 24 from the 13th Kokutais) escorted 18 G3M2 bombers. Poor visibility in the region of the target led to the fighters of the 13th Kokutai failing to discover the enemy, and the A5Ms of the 12th Kokutai became engaged in a battle against a reported 50 fighters. Nine aircraft of the Yoshitomi chutai of the 12th Kokutai reported tangling with about 50 enemy fighters and during the combat PO3c Yoshimi Minami claimed one enemy aircraft (9 victories in China and a total of 15) and Momoto Matsumura clamed three. He then received a hit in his A5M’s fuel tank; moreover, he found himself surrounded by twelve enemy aircraft. Since he had run out of ammunition, he employed a ramming tactic. Then, despite the fact that the left wing of his aircraft had been sheared off from the red ball of the rising sun outward, Minami started on his way back to base. He made an emergency landing on the banks of the Yangtze River and set his aircraft on fire. Fortunately for Minami, friendly search aircraft were able to spot him; he was rescued by a patrol boat and returned safely to base. One Japanese fighter (Sea1c Hiromitsu Takahara (Pilot 36) of the 12th Kokutai was killed) was lost in the combat. The Japanese fighters totally claimed 18 victories (alternatively 12 and 6 probables) including an old, unarmed Bellanca 28/90 biplane (evidently a reconnaissance aircraft).

On 7 July 1938, the first anniversary of the start of the Sino-Japanese war there was a huge air battle over Nanchang. At the sound of the alarm, everyone took off at once, on criss-crossing paths, I-16s, I-15bis and SBs. In this battle the Japanese adopted a very strange tactics, allowing the bombers to fly in advance without protection while the fighters, in compact groups came later, falling upon the Chinese fighters as they were exiting from their attack on the bombers. On this day four Japanese bombers and fighters were claimed shot down. In the first sudden attack B. Borodai, in an I-16 shot down a bomber. In all, the Soviet volunteers lost seven aircraft, and the I-15bis of Anton Gubenko and N. G. Kozlov were seriously damaged. Sukhorukov was killed in the battle, Gridin baled out, Rovnin was wounded and landed back at the airfield, and E. Vladimirov turned over in a rice paddy in his damaged I-15bis. Opasov shot down a bomber early in the battle, and later baled out, but was killed in the air by the Japanese. Three days later fishermen pulled his body out of Lake Poyanghu. (The physician S. Belolipetskii has however described his death differently: “K. Opasov shot down a Japanese aircraft and was preparing to land, but very close to the ground his aircraft suddenly went into a steep dive and crashed. There were no signs of bullet wounds in the body, but there were bullet holes in the coverings of the control surfaces and the stabilisers. Seemingly, the aircraft lost control at the moment when it was too low to bale out...”)
On the eve of this battle, Opasov’s I-15bis received a new motor and a heavy calibre “Colt” machine gun in addition to the four PV-1s.
In this battle three Chinese pilots were shot down. Afterward the group of Soviet fighters relocated to the reserve airfield at Tengsu.
According to the Soviet defence ministry archives, Sr. Lt. K. Opasov, and Lieutenants V.A. Kashkarov, E. I. Sukhorukov, and S. A. Khryukov were killed on 4 July 1938 so it is possible that there is some confusion regarding the battles on 4 and 7 July.

At the time of his death, Opasov was credited with 1 biplane victory, this one being claimed while flying the Polikarpov I-15bis.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1938
1	07/07/38		1	Enemy bomber	Destroyed	I-15bis		Nanchang area

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.

Sources:
Japanese Naval Aces and Fighter Units in World War II - Ikuhiko Hata and Yasuho Izawa, translated by Don Cyril Gorham, 1989 United States Naval Institute, Annapolis, ISBN 0-87021-315-6
Soviet Fighters in the sky of China, Part III - Anatolii Demin, 2000 Aviatsiia Kosmonavtika 11 (translated by George M. Mellinger)
Additional information kindly provided by Michael Fu, Yuri V. Shakhov and Erich Wang.