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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.
Piasecki soon left Platt-LePage in disgust over their haphazard approach to engineering and began to concentrate all his efforts on the P-V Engineering Forum's new single main and tail rotor model, designated the PV-2. This aircraft was only a small single-seat demonstrator. Piasecki and the P-V team hoped it would lead to a production personal transport sold to individual customers, or generate contracts for other models. While the small team of engineers focused on the design, finding actual components with little money and acute wartime shortages required expert scrounging. The group obtained a discarded Curtiss-Wright CW-1 Junior (see NASM collection) fuselage airframe and they found many of the engine accessories and transmission components in automotive dealerships or junkyards. Piasecki also enlisted the students at local engineering schools to draft blueprints - at no cost to the company. One area where Piasecki could not cut corners was the engine. It had to be compact, lightweight, and still provide sufficient power. The only suitable model that the company found was a 90 horsepower Franklin. The engineers mounted the motor vertically but it was not designed to operate in this position and the lubication system required some modification.
The PV Engineering Forum introduced another innovation to reduce rotor vibration. Engineers built the blades so that the Center-of-Gravity fell at a point forward of the Center-of-Lift. By using this arrangement, any abrupt blade deflections caused by sudden turbulence forced the blade leading edge to pivot into the wind gust. This reaction worked to stabilize the blade and further reduce vibration. In a nod to the citizen pilot, PV Engineering ingeniously designed two of the blades to fold back over the tail. This feature allowed a pilot to stow the helicopter in a standard garage, or even tow it behind his car. Once the construction phase was complete, the entire aircraft was painted silver with maroon trim and lettering, official colors of the University of Pennsylvania.
To generate business, Piasecki decided to try capitalizing on wartime military contracts. A breakthrough came on October 20, 1943, when he flew the aircraft before a large crowd of military officials and government onlookers at Washington's National Airport. The Navy showed particular interest in Piasecki's demonstration. The service had come under Congressional scrutiny for largely ignoring helicopter developments generated by Army Air Force (AAF) investment and Navy leaders were looking for a company that could cater to their specialized needs. The Navy had purchased and toyed with several Sikorsky models, but these failed to meet fleet demands for a helicopter that could carry heavy sonar gear or pick up crewmen stranded at sea. Sikorsky was stretched to the limit trying to meet AAF orders, but the PV Engineering Forum could give full attention to Navy requirements. They were also the only other U. S. company to demonstrate a practical helicopter up to that time.
Long after the Navy and PV Engineering Forum signed a contract for the new tandem rotor design, Frank Piasecki continued to risk himself and the PV-2 during flight demonstrations to promote helicopters and the company. The PV-2 won national acclaim when it starred in the newsreel called "An Air Flivver in Every Garage." This short film included sequences of Piasecki landing at a golf course and a gas station. The latter locale was particularly risky as many light poles and other obstructions bordered the narrow landing area. The film enticed some to invest in the firm but thereafter, the PV-2 only flew rarely during special functions. The helicopter remained with Piasecki until 1965 when he donated it to the Smithsonian Institution. ++++++ Forty years after the world's first powered airplane flight
by the Wright Brothers, Philadelphia engineer Frank Piasecki made
aviation history on April 11, 1943, with the second successful
American helicopter to fly, his PV-2 model, now on display at
the American Helicopter Museum in West Chester. Helicopters had
long been thought impossibly difficult and impractical by most
airplane manufacturers, leaving the field open to intrepid  A native of West Philadelphia, Frank Nicholas Piasecki was born in 1919 and grew up making model airplanes, fascinated with this exciting new industrial technology. Attending Franklin Institute conferences on Rotating Wing Aircraft in 1938 and 1939 helped inspire him to study aeronautical engineering at the University of Pennsylvania, where he met other eager students, including Harold Venzie. In 1940, the two young men established the P-V (Piasecki-Venzie) Engineering Forum, an informal evening study team to decide what to design and build with their team's growing talent and expertise. From this small beginning was to come the Piasecki Helicopter Corporation, operating in Delaware County.
Government contracts made the young manufacturing company attractive to investors, and soon a public stock offering transformed the P-V Company onto the Piasecki Helicopter Corporation, with 51 percent of the stock held by Rockefeller Associates and Felix Du Pont. After Frank Piasecki left in 1955, as a result of a bitter proxy fight, the company was reorganized as the Vertol Aircraft Corporation. In 1960 the Boeing Airplane Company acquired Vertol, and soon built anew expanded plant in Ridley Township. Boeing's helicopter division has continued to lead in development and production of large transport helicopters. Over the past decade Boeing has diversified into smaller attack helicopters and the revolutionary tilt rotor V/STOL (Vertical/Short Take-Off and Landing) aircraft, the V-22, designed originally for troop transport. Going his own way, Frank Piasecki has received numerous awards and honors for his role in American aviation, and since 1955 has been president of the Piasecki Aircraft Corporation of Essington, a Delaware County firm engaged in research on new VTOL aircraft designs. The Practical Rotor
The optimum solution to the problem is shown in the diagram (below right). This involves the articulation of the rotor blades from hinges on the central shaft. The vertical hinge allows the blade to move backward and forward, while the horizontal hinge permits the blade to move up and down. The forward and backward movement of the blades is useful, but not essential, to adequate control of the rotor disc. The advancing blade can swing back slightly as the speed of the airflow increases, while the retreating blade can move forward slightly; these two movements help to reduce the speed differential between the blades. Far more important, however, is the freedom of the blade to hinge up and down on the horizontal hinge. For as the relative airspeed of the advancing blade increases and more lift is developed, the hinge allows the blade to rise; this reduces the apparent angle of incidence of the blade and so moderates the amount of lift generated. On the other side of the rotor disc, exactly the opposite happens: as the relative airspeed of the retreating blade falls, less lift is generated than previously, and the blade falls on its hinge; this increases the apparent angle of incidence  Assembly Tips
It shouldn't be hard to install an electric motor in this little puppy..
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Piasecki
started early 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 called the Piasecki-Venzie Engineering
Forum. Venzie and Piasecki had studied engineering together at
the University of Pennsylvania. The company's first helicopter
effort, the PV-1, did not advance beyond the drawing board. This
design employed ducted-air to counteract the torque produced by
the main rotor. Although advanced, safer and potentially more
efficient than a conventional tail rotor, the concept went beyond
what was possible with available technology and Piasecki began
to lay out a new design equipped with single main and tail rotors.
Daland's most
important innovation was incorporating adjustable trim weights
on these blades to allow easy dynamic balancing. Sikorsky had
discovered the value in blades that weighed the same to minimize
destructive vibration, but Piasecki first realized that the blades
on a helicopter must have the same Centers of Gravity. Daland
devised a relatively easy way to do this. He would balance the
blades dynamically by hanging the blade from its root end and
swinging it like a pendulum. Workmen then added or removed trim
weights until the set of PV-2 blades swung the same way in frequency
and amplitude. Sikorsky only balanced his early production helicopter
blades statically, on the assembly line, but this did not cure
chronic vibration.
The PV-2 first
flew by accident. A frayed clothesline tethering the aircraft
safely to the ground suddenly snapped and the helicopter became
airborne. Frank Piasecki was at the controls and managed to safely
land, despite his complete lack of previous flight experience
in helicopters. He had only fourteen hours of flight time in fixed-wing
aircraft. This brush with disaster did not deter the plucky pioneer
and Piasecki remained the chief test pilot for the PV-2, in addition
to his duties as chief engineer and company president. At that
time, the company was not generating any income and it had not
attracted any financial backing so the financial situation was
dire. The PV-2 was PV Engineering's most valuable asset and the
firm handled it with extreme care, flying only as necessary for
testing.
By the end of 1940 Piasecki had
joined the Platt-LePage Company as assistant to the designer Elliot
Daland; Daland was nearly blind, and Piasecki served as his "eyes."
The Platt-LePage plant lay next to the General Steel Castings
Foundry, which later became the Boeing-Vertol assembly plant on
Route 29 1. In 1943 Frank Piasecki was managing his own company,
P-V Engineering Forum, after the departure of his partner; his
successful design of the PV-2 became clear when Frank himself
learned to fly it, after only twelve hours of airplane piloting
experience. After his first flight in April of 1943, he took the
new model to Washington, D. C., and demonstrated the machine's
precise fingertip control characteristics. Wartime needs brought
a Coast Guard contract in January 1944. The Navy had been slow
to realize the potential of the helicopter, but at the urging
of Congressman Harry S. Truman finally agreed to this contract
for development of a large anti-submarine helicopter. Piasecki's
group responded with their large tandem rotor model XHRP-X, affectionately
dubbed the "Flying Banana."
The basic problem
with any rotorsupported aircraft, in any condition other than
when it is hovering in still air, is the tendency of the different
amounts of lift generated by the advancing and retreating blades
of the rotor to roll the aircraft. In an aircraft moving forwards,
it is clear that the effective speed of the airflow over the advancing
blade is its own rotational speed plus the forward speed of the
aircraft, whereas that over the retreating blade is its own rotational
speed minus the forward speed of the aircraft. The blade with
the higher airflow speed will generate more lift than the other
blade, and this difference will tend to roll the rotor disc and
in turn the whole aircraft.
