Vietnam improves C-130 transport aircraft into Truong Sa protection aircraft
After 1975, to protect Truong Sa, aviation technicians of the Air Defense - Air Force researched and improved the American C-130 transport aircraft into a bomber.
In 1976, the Air Defense - Air Force asked the Technical Research Department officers to come up with a plan to improve the C-130 transport aircraft into a bomber to serve the protection of Truong Sa.
One morning in late September 2012, the reporter went to the house of one of the former cadres who participated in the C-130 improvement project, Colonel Huynh Tung. Coincidentally, that day, his teammate who also carried out the C-130 improvement project – Colonel Nguyen Kim Khoi had just come from inside the
C-130 Hercules transport aircraft
Improving aircraft to protect Truong Sa
The C-130 is a four-engine turboprop tactical transport aircraft developed and manufactured by Lockheed (USA) since the 1950s. The C-130 was designed for the primary mission of transporting cargo and troops.
During the war of aggression in Vietnam, the US also developed the AC-130 variant equipped with artillery and machine guns to attack the Truong Son road area to block the transportation route of our troops.
The US military also provided a small number of C-130s to the Republic of Vietnam Air Force.
Cockpit of a C-130 Hercules aircraft.
After liberation, our army captured several C-130s in good working condition and used them for the war on the Western border.
Back to the story of the C-130 bomber improvement to protect the Truong Sa archipelago. In fact, the C-130 aircraft according to the design plan can drop 7-ton bombs by parachute.
However, "if we use the parachute bomb dropping method, the ground radar guidance system must be good. If we fly over the sea, can this radar system be used? Moreover, is it still working now?" Mr. Huynh Tung discussed with his teammate Nguyen Kim Khoi at that time.
Thereby, the two men agreed to make a decision to improve the C-130 bombing method according to the cargo drop plan. “Comrade Khoi was in charge of developing a plan to fix the bomb, remove the detonator safety pin, remove the bomb package pin, the type of bomb used, the location of the aiming device, and calculate the bomb aiming table. I carried out the improvement of the bomb slide system, the bomb fixing belt cutting system, determined the necessary angle of attack (slope) of the plane when dropping the bomb so that the bomb automatically slides out, calculated the center of gravity of the plane when fixing the bomb in the compartment and the bomb moving on the slide rail when dropping,” Mr. Tung recalled.
US aircraft use Russian sights
Regarding the bomb assembly and bomb dropping, Vietnamese technical staff
There are two roller systems in the compartment, each person can push a bomb package inside. When dropping a bomb, the plane reaches the necessary angle of attack for the bomb to slide out.
“According to the agreed plan, we used Mk-81 bombs fixed in 8 packages, each package had 4 bombs, arranged in 2 rows, each row had 4 bombs. We dropped 2 packages at the same time or one package at a time. With this amount of bombs, the plane could carpet destroy the target over an area 500m long and 50m wide,” said Mr. Tung.
As for the bombsight, this is a difficult problem because we do not have the equipment available. However, Vietnamese engineers
“We used the Il-28 bomber’s sight on the C-130. To install the sight, we drilled a hole in the belly of the plane in front of the cargo compartment to put the sight in,” Mr. Kim Khoi recalled.
During the process of solving the problem, they also encountered many difficulties such as how to make the bomb automatically slide out while the plane's center of gravity remained within limits.
“When I calculated the plane's center of gravity, the 8 bombs were within the limit, but when I let 2 of them slide out, the remaining 6 slid back and then the center of gravity went beyond the allowable limit.
After thinking for a long time without finding the cause, I immediately met a pilot of the Saigon Army who had flown the C-130 to find out. Through the story, I understood the reason why the center of gravity was out of bounds when the bombs were moving. Therefore, I found a solution: before dropping the cargo, the flaps were released to shift the focus of the wing's aerodynamic lift force back, so the bomb slid back while the center of gravity of the plane was still within bounds.
Colonel Nguyen Kim Khoi (left) and Colonel Huynh Tung (right) participate in the work of improving the C-130 transport aircraft. Photo: Phuong Hong
To determine the angle of attack of the plane when dropping the bomb, I placed the bomb on the slide rail on the plane's floor, slowly raised the nose of the plane and used a ruler to determine the angle of attack of the plane so that the bomb moved on the slide rail by 3 degrees," Mr. Tung recounted.
Completed all calculations on bomb installation plan and bomb sight. Together they wrote the plan to submit to the military branch for approval. With the agreement from the Military Branch Command, Regiment 918 brought a C-130 number 04 to workshop A41 for improvement.
Successful test
At the end of 1976, the Air Defense - Air Force organized the first test flight of the modified C-130 aircraft. When dropping bombs, the C-130 will fly at an altitude of 4,000m, at a speed of 250km/h.
The testing was divided into two steps. The first step involved removing all the fuses from 32 bombs mounted on eight racks and flying in a closed loop at Tan Son Nhat airport to check the stability of the bombs during takeoff and landing. The second step involved a C-130 dropping real bombs on a target at Rang Rang field airport (Dong Nai). Both test flights were successful.
However, during the actual bombing, a situation arose where a bomb package did not open its belt, even though the belt safety pin had been pulled. “To overcome the situation where a bomb package did not open, I suggested to Khoi to install a board above the bomb package so that when the bomb package flew into the air, the aerodynamic force would knock the board up to quickly unlock the bomb package,” Mr. Tung recounted.
After completing the plan, the research team continued testing and achieved good results.
The original purpose of the C-130 improvement research project was to protect Truong Sa. However, in 1977, the situation on the Western border
And during the 1979 Southwestern Border Campaign, the C-130 squadron took off many times to bomb Khmer Rouge targets, destroying many tanks, artillery, warehouses, and enemy command posts, contributing to our army's victory in defeating the invaders and helping the Cambodian people escape genocide.
According to VPchinhphu-M
