One year before the United States entered the Vietnam War, the U.S. Army solicited proposals for the Advanced Aerial Fire Support System (AAFSS) program, which aimed to be the first program in history to design a helicopter from the ground up for armed military action. By February of 1965, the Army awarded contracts to both Lockheed and Sikorsky for further development on their respective designs, with Sikorsky fielding an entrant they called the S-66, and Lockheed submitting their own CL-840 Cheyenne. Ultimately, Lockheed’s proposal would win out and secure a developmental contract for 10 of their combat helicopters, only to have the program unceremoniously scrapped in 1969 after Lockheed had failed to make satisfactory progress addressing a number of technical issues within Cheyenne.

Following the failure of the Cheyenne, the Army was left operating their backup-plan: the less advanced and as such, less complex and expensive, Bell AH-1G Cobra that would go on to earn renown for the Army and Marine Corps for decades thereafter. But back in the Sikorsky offices, the firm whose namesake invented the first practical helicopter in history, set back to work on their designs for an attack helicopter nonetheless.

An attack helicopter without a defense contract

Knowing full well that the United States was rapidly learning the value of capable military helicopters like the UH-1 Iroquois (better known today as the “Huey”) in Vietnam, Sikorsky set about work on another attack helicopter design. This new rotorcraft would leverage lessons they’d learned developing the S-66, as well as what they were able to glean from the Cheyenne’s failure. By mid-1969, Sikorsky began initial development on their new high-speed helicopter gunship: the S-67 Blackhawk.

With no defense contract funding their development, the United Aircraft Corporation chose to fully fund the S-67 program on their own, keen to position themselves well for the next military contract seeking a capable helicopter gunship. By January of 1970, Sikorsky’s executive vice president, John A. McKenna, was tasked with overseeing the program, with stipulations calling for a helicopter that weighed between 18,000 and 20,000 pounds and could reach speeds as high as 200 knots (or around 230 miles per hour) in a shallow dive.

McKenna took his orders and dove in, expediting development by combining new design elements with the old, making a new helicopter that leveraged components and methodologies that had already proven themselves.

“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 greatly reduced cost and technical risk; high performance, ease of maintenance, and early availability.”

They built the S-67 Blackhawk in just seven months

That approach would pay off when McKenna’s team produced their first working prototype just seven months later. The new S-67 Blackhawk had swept wings and a large cambered vertical fin for stability. In fact, the S-67 was the first helicopter ever to use such a design to benefit directional stability and effectively proved the concept sound.

While the tail rotor managed torque compensation while hovering and during low-speed flight, the fin would take over that responsibility by cutting through the air whenever the helicopter exceeded 46 miles per hour. If the tail rotor of the helicopter were ever damaged, the S-67 could even continue to fly back home thanks to its groundbreaking design.

The helicopter’s wings, which could be removed for different mission load-outs, came equipped with extendable airbrakes that could be fully opened or closed in less than three seconds. These air brakes literally cut the time it took the Blackhawk to stop in half under most flying circumstances, giving it unprecedented maneuverability. Between the air-brakes, 27-foot wingspan, and stabilizing fin, the S-67 Blackhawk proved extremely stable at nearly all speeds, making it exceptional for target acquisition and engagement.

The fuselage of the helicopter itself was rather narrow, with the pilot and gunner sitting in tandem within the three-foot-10-inch-wide cockpit. The S-67’s narrow-body gave it a slimmer profile, making it harder to target, while also benefitting the aircraft’s overall aim of being both fast and nimble. That speed came from two General Electric T58-GE-5 1,500 horsepower turbine engines, which pushed the S-67 Blackhawk to one speed record in December 1970 (216.8 mph over a 1.86-mile course), and then another just five days later (220.9 mph on a longer course). That second helicopter speed record would stand for nearly a decade t follow.

Quick, nimble, and packing a whole lot of firepower

The S-67 Blackhawk wasn’t just fast, it also packed one hell of a punch. When on an attack mission, the helicopter could carry more than 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 to engage heavy armor or tanks.

Despite being a sleek and narrow aircraft, the cabin of the S-67 was modified to be able to transport as many as six fully kitted Soldiers in the space behind the cockpit, and it could reach speeds in excess of 165 miles per hour while doing it. If tasked with search and rescue operations, auxiliary fuel tanks could be mounted on the helicopter’s wings, giving it a range of 600 miles at high speed. The same cabin that could be used to ferry troops could also be filled with electronic equipment intended for observation and surveillance.

Despite being capable of carrying a significant payload into combat, the S-67 was also incredibly nimble. Test pilots had no trouble performing rolls, split-S maneuvers, and even loops in the helicopter. The S-67 Blackhawk was a jack of many trades, all of which interested in the Army, who were now once again on the market for a replacement for the failed Cheyenne. In fact, the helicopter proved so impressive, the Army gave Sikorsky a list of small things they’d like changed and offered up four small developmental contracts, each for around $100,000 (or around $675,000 in 2021 money), to further test the platform.

Killed off by the Apache, and then by a tragedy

The Army was impressed with the S-67’s performance and began pitting it against the Bell Model 309 King Cobra–both of which were considered as potential replacements for the troubled Cheyenne. That is, until 1972, when the Army announced its plans to procure a new helicopter in an effort dubbed the Advanced Attack Helicopter (AAH) program. The Army wanted a helicopter that was more powerful than the AH-1 Cobra, with better range and improved performance.

Sikorsky’s S-67 Blackhawk seemed well suited for the job, as was Bell’s King Cobra, but both ultimately lost out to the Hughes Helicopter YAH-64A — the aircraft that would go on to become the legendary AH-64 Apache.

But Sikorsky was undeterred. They knew they had a capable combat helicopter, and if the United States wasn’t interested in purchasing them, it seemed entirely feasible that a friendly foreign government might. In late 1972, the S-67 was packed up and sent to Europe, before going on to the Middle East to give different nations an opportunity to see the Blackhawk in action. Upon returning, the Army once more expressed interest in the helicopter, funding a series of modifications including a modified fan-in-fin, though that modification was later removed.

In 1974, the S-67 Blackhawk was once again boxed up for a European tour, where it was slated to perform alongside Sikorsky’s CH-53 Super Stallion, which had made its first flight earlier that year. Unfortunately, during a press-preview flight, Sikorsky’s only working prototype of the helicopter clipped the ground while executing a low altitude roll. The helicopter was destroyed and both men on board would ultimately die from their injuries.

Despite the progress Sikorsky made with the S-67 Blackhawk, the tragic death of two Blackhawk pilots coupled with a lack of interest from military buyers prompted Sikorsky to end the program. But that wasn’t quite the end of this story. In October of the same year, Sikorsky’s new utility helicopter, the H-60, would make its first flight, and by 1979 it would enter service for the Army as the UH-60 Black Hawk... because a cool-sounding name is a terrible thing to waste.

This article was first published by Sandboxx.

Image: Wikimedia Commons