The Sikorsky S-67 Blackhawk was a privately funded, experimental assault helicopter constructed in 1970 using Sikorsky Aircraft’s research and development resources. Designed as a two-seat, tandem aircraft based on the dynamic drive and rotor systems of the Sikorsky S-61, it aimed to function as an attack helicopter or transport up to eight soldiers into battle.

Here’s What You Need to Remember: The S-67 Blackhawk wasn’t only swift but also carried a significant amount of firepower. During an assault mission, the helicopter could transport over 7,000 pounds of weapons and ammunition, including a turret-mounted 7.62 machine gun, 20 and 30mm cannons, 40mm grenade launchers, and even wing-mounted rockets or TOW missile pods for engaging heavy armor or tanks.

Sikorsky’s H-60 series of Black Hawk helicopters gained a legendary status for their battlefield capabilities, but nearly a decade before the first UH-60 entered service, Sikorsky had a different Blackhawk in mind: The S-67 attack helicopter.

A year before the United States joined the Vietnam War, the U.S. Army requested proposals for the Advanced Aerial Fire Support System (AAFSS) program, which aimed to be the first-ever program to design a helicopter from scratch for armed military action. By February 1965, the Army awarded contracts to both Lockheed and Sikorsky for further development on their respective designs. Sikorsky submitted their S-66, and Lockheed presented their CL-840 Cheyenne. Ultimately, Lockheed’s proposal won, securing a developmental contract for 10 of their combat helicopters. However, the program was abruptly canceled in 1969 after Lockheed failed to address several technical issues with the Cheyenne.

Following the Cheyenne’s failure, the Army was left operating their backup plan: the simpler, less complex, and less expensive Bell AH-1G Cobra, which would gain fame in the Army and Marine Corps for decades to come. Meanwhile, back at the Sikorsky offices, the company responsible for inventing the first practical helicopter in history went back to work on their attack helicopter designs.

An attack helicopter without a defense contract

Aware that the United States was quickly learning the value of capable military helicopters like the UH-1 Iroquois (better known today as the “Huey”) in Vietnam, Sikorsky began work on another attack helicopter design. This new rotorcraft would apply lessons they had learned from developing the S-66 and insights gained from the Cheyenne’s failure. By mid-1969, Sikorsky initiated the development of their new high-speed helicopter gunship: the S-67 Blackhawk.

Without defense contract funding, the United Aircraft Corporation decided to fully finance the S-67 program, positioning themselves for the next military contract seeking a competent helicopter gunship. In January 1970, Sikorsky’s executive vice president, John A. McKenna, was assigned to oversee the program, which called for a helicopter weighing between 18,000 and 20,000 pounds and capable of reaching speeds up to 200 knots (around 230 miles per hour) in a shallow dive.

McKenna took the assignment and accelerated development by combining new design elements with the old, creating a new helicopter that utilized proven components and methodologies.

“The S-67 is a combination of proven components and new design concepts,” a Sikorsky fact sheet stated.

“The result is a new helicopter weapons system at a greatly reduced cost and technical risk; high performance, ease of maintenance, and early availability.” They built the S-67 Blackhawk in just seven months.

McKenna’s approach paid off when his team produced their first working prototype in only seven months. The new S