When Igor Sikorsky began to publicly demonstrate his VS-300 helicopter in 1941, he called it the automobile of the future. This idea quickly captured the public imagination and enthusiastic helicopter designers stepped forward to produce the next aerial version of the Model T. On April 11, 1943, Frank Piasecki became the second American to successfully fly a helicopter of his own design, the Piasecki-Venzie PV-2. He built it with far fewer resources than Sikorsky had available to construct the VS-300, yet the PV-2 flew with an unprecedented smoothness and stability. Ironically, Frank Piasecki intended his first helicopter design to be the forerunner of a revolution in personal transportation, but his company actually evolved into one of the foremost manufacturers of large cargo helicopters sold primarily to the military.
Gift of Frank Piasecki
Country of Origin: United States of America
Rotor Diameter: 7.7 m each (25 ft 2 in)
Length: 7.7 m (25 ft 5.25 in)
Height: 2.36 m (7 ft 9 in)
Weights: Empty, 327 kg (720 lb)
Gross, 454 kg (1,000 lb)
When Igor Sikorsky began to demonstrate his VS-300 helicopter, he presented it as the automobile of the future. This idea quickly captured the public imagination, and a number of enthusiastic designers stepped forward to produce the next aerial version of the Model T. On April 11, 1943, Frank Piasecki became the second American to successfully fly a helicopter of his own design. His PV-2 was constructed with fewer resources than Sikorsky's aircraft, yet it flew with a smoothness and stability that was lacking in the VS-300. Ironically, while Frank Piasecki's first helicopter design was intended as the shape of things to come in personal transportation, his company established itself as the foremost manufacturer of large helicopters sold primarily to the armed forces.
Piasecki had an early start in the helicopter industry when he joined the Platt-LePage Aircraft Company in 1940 as an engineer working on the XR-1 (see NASM collection). At the same time, he started a small consulting firm with Harold Venzie, the P-V Engineering Forum. The company's first helicopter effort, the PV-1, did not advance beyond the drawing boards. That design was to have used ducted air as a safer and more efficient alternative to a tail-rotor. However, it became obvious that this could not be done efficiently with the current technology and plans were formulated for a new design along the lines of Sikorsky's tail-rotor equipped model.
Piasecki soon left Platt-LePage in disgust over their haphazard approach to engineering, and concentrated all his efforts on the P-V Engineering Forum's new model, designated the PV-2. This design was only intended as a small single-seat demonstrator, either as the basis for a production aircraft, or to generate contracts for other models. While the small team of engineers came up with a sound design, finding actual components with little money and acute wartime shortages required expert scrounging skills. The airframe came from a discarded Curtiss-Wright CW-1 Junior (see NASM collection) and many of the engine accessories and transmission components were found in automotive dealerships or junkyards. Piasecki enlisted local engineering schools in drafting blueprints as exercises for the students - at no cost to the company. One area where corners could not be cut, however, was the engine. It had to be compact, light weight, and yet provide sufficient power. The only suitable model that the company was able to find was a 90 hp Franklin. To increase engine efficiency, the motor was mounted vertically, which necessitated some minor alterations to compensate for the modified lubrication pattern. The entire aircraft was painted in silver and maroon, which were Piasecki's favorite colors.
While the transmission was mostly a motley assortment of discarded automobile parts, the rotor blades were masterpieces of engineering that contributed greatly to the success of the PV-2. Elliot Daland, a venerable and experienced engineer who had also worked on the XR-1, oversaw construction of the three-bladed rotor. Steel tubing was used for the main spar. Solid spruce was used to form the leading edge, and the remainder of the rotor airfoils was formed with birch plywood ribs. The assembly was glued together, not riveted, to provide a stronger, more reliable bond. After final adjustments, the rotor blades were covered with fabric. The most important innovation in the rotor blades was the incorporation of adjustable trim weights that allowed for easy dynamic balancing. Sikorsky had realized the importance of blades that weighed the same to minimize destructive vibration, but Piasecki was first to realize that the center-of-gravity should also be identical. He thought the best way to do this was to dynamically balance the blades by swinging them and then varying the adjustable weight until all of the blades swung at the same rate. Initially, Sikorsky only used static balancing during blade manufacture, which resulted in chronic vibration problems in all his early models. Another innovation to reduce rotor vibration pioneered by the PV Engineering Forum was configuring the blades so that the center of gravity was forward of the center of lift, causing any abrupt deflections to pivot the leading edge in the opposite direction, resulting in a stabilizing mechanism. The rotor was ingeniously designed so that two blades could swing back over the tail, allowing the entire aircraft to be stowed in a standard garage, or even be towed behind a car.
The PV-2's first flight occurred by accident when a frayed clothes line that was intended to keep the aircraft tethered broke and the helicopter became airborne. Frank Piasecki was at the controls, and managed to safely land the aircraft in spite of the fact that he had no previous flight time in helicopters and only fourteen hours in fixed wing aircraft. He remained as the chief test pilot for the PV-2, in addition to his duties as chief engineer and company president. Because of the company's dire financial situation, resulting from no income or financial backing, the PV-2 was handled with extreme care and flown only as necessary for testing. To generate business that would result in essential income, Piasecki decided to try to capitalize on wartime military contracts. His breakthrough came on October 20, 1943, when he flew the aircraft at Washington's National Airport for a large crowd of military officials and government onlookers. The Navy was particularly interested in Piasecki's demonstration as it had come under Congressional scrutiny for largely ignoring helicopter developments generated by Army Air Force (AAF) investment, and was looking for a company that would be more focused on their specialized needs. The Navy had purchased some Sikorsky models, but these did not meet its demands for a helicopter that could carry heavy sonar gear or pick up a number of stranded crewmen from a torpedoed vessel. Sikorsky was also stretched to the limit meeting AAF demands, and the PV Engineering Forum was the only other company to have demonstrated a practical helicopter. Additionally, the Navy could be guaranteed to have Piasecki's full attention.
The PV-2's demonstration allowed Frank Piasecki to successfully approach the Navy with his proposal for a prototype tandem rotor design that could serve as the basis for a large rescue and anti-submarine warfare (ASW) helicopter. This contract became the PV-3, later known as the X-HRPX Dogship (see NASM collection). Along with outside investors, the resulting HRP-1 production contract provided enough cash inflow to allow the company, in its various forms, to become the prime supplier of large transport helicopters for several decades.
Even though the PV-2 had accomplished its goal by demonstrating the PV Engineering Forum's ability to construct a practical helicopter, its useful days were not over. Once it appeared that a government contract would be guaranteed, Frank Piasecki began to take more risks with the aircraft to promote helicopters in general and his company in particular. The PV-2 achieved national acclaim when it starred in a newsreel entitled "An Air Flivver in Every Garage." The short film included sequences of Frank Piasecki landing at a golf course and a neighborhood gas station. The gas station sequence was particularly risky as many obstructions bordered the narrow landing area. After the film achieved its goal of enticing investment, the PV-2 was only flown for special functions, but it remained with Piasecki, until 1965 when he donated it to the Smithsonian Institution. The goal of mass-produced helicopters for suburban garages turned out be an unrealistic fantasy, but the diminutive PV-2 helped to demonstrate to the nation that helicopter were here to stay.
Rotor Diameter: 7.67 m each (25 ft 2 in)
Length: 7.75 m (25 ft 5.25 in)
Height: 2.36 m (7 ft 9 in)
Weight: Empty, 326.6 kg (720 lb)
Gross, 454 kg (1,000 lb)
Engine: Franklin, 90 h.p.
References and Further Reading:
Adams, Frank, ed. The Golden Years. Philadelphia: Frank M. Adams, 2000.
Labermont, Paul. Helicopters and Autogyros of the World. Cranbury, N.J.: A.S. Barnes and Company, Inc., 1970.
Spencer, Jay P. Whirlybirds: A History of the U.S. Helicopter Pioneers. Seattle:
University of Washington Press, 1998.
R. D. Connor