Hiller 360 - History and technical description

This helicopter differed from others for its innovative control system known as "Rotormatic" which is later described. 

Stanley Hiller, a boy wonder

Stanley Hiller Jr. was born on November 15, 1924 in San Francisco and grew up in Berkeley, California. His father Stanley Hiller Sr. was a businessman, engineer, aviator and inventor.
Stanley Hiller Jr. had a natural talent for mechanics. As a young boy, he took up model aircraft. At the age of 13, he built a model aircraft powered by a gasoline engine. One day the plane was damaged. Everything was lost except the small engine. This accident took Stanley Hiller away from aviation for a while. Although demoralised he recovered the engine and returned to the workshop in the family garage. Within a few days he built a new toy by mounting the engine on a car-type chassis made from scrap metal and wood. 
Gasoline-powered model racing cars were very popular in the 1930s and 1940s. They were raced in circle tied to a central pole.
Stanley Hiller began building model racing cars for himself, his friends and friends of friends. In 1940, demand rose to a point where he and his father decided to set up a company named Hiller Industries for the large-scale production of the Hiller Comet. In 1943, at the height of production, more than 350 models per month were being produced on the assembly line organised in the garage of the family home. The people employed were mostly high school students who worked during their free time. The business generated a gross annual turnover of over $100,000.
With the exception of items such as spark plugs and magnets, Stanley Hiller built the complete models, including a single-cylinder engine that delivered one horsepower when pushed to 18,000 rpm.
This was made possible with the help of his father and a draftsman, with whom he invented a die-casting machine based on a cooling process that increased the strength of aluminium castings.
In addition to the Hiller Comet, the company produced other aluminium products such as household goods, skillets, pots, clothes hangers and toys such as the Atom Ray Gun, a water pistol.

In 1942 when the government was combing cities, towns and villages for sub-contractors, the Army scouts came upon Hiller’s small factory. The quality of the products manufactured at Hiller Industries led to government contracts for production of magnesium bombs and aircraft parts.
In those years Stanley Hiller became intrigued by helicopters. He had seen motion pictures and photographs of helicopters in flight, but he had never seen one “in the flesh”. The youth bought all the books on helicopter development that he could find. They were extremely few. He made a tour of libraries in the San Francisco bay area studying helicopter designs dating back as far as the 16th century. The magazines articles and clippings found, many of which showed Igor I. Sikorsky at the controls of his VS-300, were of little help, but they contributed to strengthen his interest in helicopters. He read and assimilated everything he could lay his hands on. At about this time he entered the University of California at Berkeley. He spent about six months on the sketches at the time working at Hiller Industries, where war production had meanwhile increased considerably.
Stanley Hiller’s interest in helicopters grew to such an extent that at the end of his freshman year he left the university where he had been majoring in mechanical engineering to spend all time on the helicopter development. As he progressed he requested the help of Harold Sigler, a draftsman employed by Hiler Industries to draw in detail from original sketches the helicopter he had in mind. From the sketches they built models from which they obtained valuable experience.
On behalf of Hiller Industries Stanley Hiller went East on a business trip during which he stopped off at Wright Field, the Army’s aircraft testing center. There, officials were just starting test with the first Army helicopters, and Hiller saw a helicopter for the first time. He talked to Army officers in charge of helicopter development in an effor to pick up any information that might prove of help. When he returned home he made more models with new changes in design. After a few months he and Siegler had reached what they thought at the time was the answer to controllability, one of their big problems they were faced with.
In December 1942, after some years of study, model building and testing, he started work on his first helicopter, the XH-44 “Hiller-Copter”. 
One of the first difficulties was to obtain a motor, an difficult task during the war period. Hiller and Siegler built a half-scale model of the coaxial control mechanism that was the heart of the helicopter. The youth took the model first to Wright Field, but the Army wasn’t interested. Then he continued to Washington, from an office to another. Finally he captured the interest of some NACA’s members and obtained the engine and other material needed for the construction of a single-place from the Aircraft division at Wright Patterson Base.
In the course of 1943 Stanley Hiller aided by Harold Siegler, Jack Galliano, a craftsman, and Bert Cann, a skilled welder, built the XH-44 in an automobile garage in Oakland (California).
On May 14, 1944 the XH-44 “Hiller-copter” made its first test flight from the concrete driveway of the Hiller’s home. Stanley Hiller, who had obtained a student pilot's licence at Oakland airport, taught himself to fly the helicopter. The knowledges he had obtained in flying aeroplanes werent of much help when he first took the helicopter off the ground. For safety’s sake the helicopter was tethered to the bumper of his automobile.
On July 4, 1944, after some setbacks, Stanley Hiller made the first free flight at the controls of the “Hiller-copter” inside the California Memorial Stadium in Berkeley.
The Hiller XH-44 was flown publicily on the Marina Green in San Francisco on August 30, 1944.

Development work continued in association with Henry J. Kaiser, a famous American industrialist, in the Hillercopter Division of the Kaiser Cargo Company.
During this period, the company built three prototypes known as X-2-235, equipped with counter-rotating coaxial rotors developed on behalf of the US Navy.
Collaboration with Kaiser ceased by mutual consent at the end of the war, when the latter's interest turned to automobile production.
In 1945, United Helicopter Inc. was formed and continued to work on the development of helicopters.
The company name Hiller Helicopters was adopted in 1951 to avoid confusion with other companies.
From Oakland Stanley Hiller and his team moved to Palo Alto, where a temporary facility downtown was chosen to design and build a series of experimental aircraft.
Among them was the two-seat UH-4 Commuter that first flew in 1946, a helicopter with counter-rotating coaxial rotors. Various problems associated with this type of rotor prompted the company to study single-rotor models.
The Hiller J-5 that flew at the end of 1946 was built to test a simplified control system that used the jet thrust at the end of the tail boom to compensate for torque, as in the MD 520N Notar.
The NC-5, a two-seat single-rotor helicopter tested in 1947, showed the advantages of a new aerodynamic control system known as “Rotormatic control” that ensured great stability.
Rather than acting on the rotor blades by means of levers and linkages, the pilot achieves cyclic control by operating the cyclic control bar (commonly called “stick” or on this model also the T-bar) which is attached to the swashplate. In this way it directly drives an aerodynamic servo-rotor which in turn controls, with limited effort for the pilot, the cyclic tilting of the main rotor blades. The symmetrical airfoil of the servo-rotor provides the Hiller 360 with exceptional inherent stability as shown in the photo below.

From the design principles worked out on the Hiller NC-5 a new model known as the Hiller 360X was developed.
The Hiller 360X (X for experimental) took to the air on November 11, 1947 in a flight that held no surprises, thanks to some 150 hours of operational testing by test pilot Frank Peterson on the Hiller NC-5. The cabin of the new prototype was completely enclosed like that of an automobile. The helicopter was first presented to the US Army and Navy, then to the public on December 11, 1947.

Technical characteristics

The Hiller 360 is a three place side-by-side helicopter with a two-blade main rotor. The main rotor blades (made by Parsons Industries Inc.) are of solid wood laminations. The body of the blade is in fact essentially made up of numerous strip and block wooden laminations designed to provide a strong but highly flexible blade. The entire blade surface is covered with fiberglas cloth with the leading edge and tip covered with an additional stainless steel sheet. The tail rotor is of all metal construction.
By virtue of the dual control arrangement the Hiller 360 may be flown from either the left or center seats depending on whether the pilot is flying solo or is carring one or two passengers. The overhead cyclic bar incorporates a mechanical trim which is directly connected through a metal cable to the swashplate. Directional control is obtained with conventional type rudder pedals which vary the pitch change of the two blade metal tail rotor. There are two pairs of pedals, one placed centrally and one on the left side.

The helicopter was usually delivered with a simple plexiglas windshield, but there was also the possibility to enclose completely the cabin.
The helicopter normally came with a tricycle undercarriage with oleo-pneumatic shock absorbers and brakes on the main wheels, but it could also be fitted with skids or floats for amphibious operations.
The Hiller 360 was originally powered by a six cilinders fan-cooled Franklin 6V4-178-B33 engine with a maximum power of 134/178 kW/hp at 3'000 rpm. The fuel system is relatively simple. There is a mechanical pump driven by the engine and a second electrically-driven auxiliary fuel pump. The tank haves a capacity of 102 litres (27 US gallons).

The throttle has a correlator and is linked to the collective control lever. There is a finger-tip lever for automatic override for final adjustment of the engine speed to most efficient rotor rpm and pitch setting for various loads und cruising speeds. Magneto, filters, generator, starter as well as others accessories are easily accessible. For the ordinary maintenance works no special tools are required.
Equipment for crop-dusting, air-mail, cargo, photographic and survey operations could be easily installed without affecting its performance or flight characteristics.

Maintenance

A brochure published in 1949 indicates that the maintenance of the Hiller 360 could be easily made. The inspection after 25 respectively 50 hours of flight required 3 hours of work for a mechanic (without the engine controls). The 100 hours inspection required 20 hours. The general revision after 600 hours of flight required 300 hours.

Performances

With a total takeoff weight of 965 kg/2,127 lbs (1 pilot, 2 passengers, 100 litres/2 USG of fuel, 10 litres/2,64 USG of oil) the Hiller 360 has a maximum cruising speed of 135 km/h and a standard cruising speed of 122 km/h/76 mph. The maximum rate of climb is 220/720 m/ft min. At the MTOW of 1'020 kg (2,247 lbs) the helicopter has a service ceiling of 3'100 m (11,170 ft) and can hoover in ground effect up to 1'450 m (4'760 ft), while its range is 250-300 km (155-186 miles).

Dimensions, weights and loadings

The Hiller 360 has a main rotor with a diameter of 10.67 m, and a tail rotor with a diameter of 1.67 m. The semi-monocoque fuselage has a total lenght of 8.08 m. Its maximal height is 2.89 m.
The empty weight of the helicopter equipped with a tricycle landing gear is 657 kg. In the original version the maximum takeoff weight (MTOW) is 1'020 kg. Deduced the standard weight of the pilot 77 kg and the reserve of fuel and oil for one hours of flight (36 kg) the payload is 247 kg.

The Hiller 360 in Switzerland

The Hiller 360 HB-XAI (s/n 120 – b/y 1949) was the first civil helicopter to be registered in Switzerland. It was a second-hand aircraft previously registered in the United States (where it flew with the registration N8120H) purchased by Air Import of Lucerne at a price of about 120'000 Sfr.
The technical control was made by the Swiss authorities (FOCA) on August 12, 1949 on the aviation field of Biersfelden/BL. From that date on the helicopter was used by Albert Villard, the first Swiss helicopter pilot, to show the potentialities of the new aircraft.
On November 17, 1949 HB-XAI became the first helicopter to perform a roof-landing. It landed on the roof of the Jelmoli store in Zürich. 
On January 6, 1950, during the celebration of the Epiphany (the Italian counterpart of Santa Claus), it was presented in Milan. This was the first time a helicopter landed in the Cathedral Square in the centre of the city and large crowds (several dozens thousands) were assembled to witness the event.
The Hiller 360 HB-XAI flew in Switzerland for a short time. In September of 1950 it was sold to Italian helicopter company ELA (Elicottero Lavoro Aereo) based in Milan and received the Italian civil registration I-ELAM.
In the short period of service in Switzerland it was primarely used for flight demonstrations, passengers flights and the training of the first Swiss pilots.

Did you knew that…

On 31 July 1949, 12-year-old Terence “Kayo” Hallinan, along with a group of friends and a guide, was on a horseback excursion in the High Sierra when he was suddenly knocked to the ground near Benson Lake (2,310 metres). By falling his head hit a rock violently and suffered a fractured skull. The doctor alerted by the Yosemite National Park ranger took 11 hours on horseback to reach the boy, who remained unconscious for a long time. Given the delicate situation, he suggested an evacuation by air.
The US Army had initially considered using one of its Piasecki HRP-1 Rescuers, but quickly realised that the twin-engine aircraft was not capable of landing and take-off again at that altitude. He also considered using a Grumman HU-16 Albatross aircraft, a twin-engine amphibious aircraft produced by the US company Grumman. Given the surrounding mountainous terrain, this option was also quickly discarded.
Experienced pilot Knute Flint, co-owner of the Armstrong-Flint Helicopter Company in Fresno, attempted to reach Lake Benson at the controls of a Bell 47B, lightened as much as possible, but his attempt failed. Returning to the ranger station, he said that rescuing “Kayo” by helicopter or other means was impossible given the high altitude the aircraft had to reach.
Upon learning of the incident, Hiller pilot Gerald Arthur (“Jay”) Demming (1918-1996), who had previously been employed as a test pilot for the Bell Aircraft Corporation, offered to bring help to the boy.
The day after Flint's attempt, a truck carrying a Hiller 360 was brought to the ranger station at White Wolf where it was reassembled. 
The press, informed of the incident, set up at White Wolf Lodge to follow the rescue operation. After preparing the helicopter Jay Demming made a reconnaissance flight to familiarise himself with the terrain. On his return he stated that the situation was even worse than he had imagined.
Undeterred, he made another flight later. The helicopter reached an altitude of 2,830 metres (9,300 feet) and headed towards Lake Benson. At altitude, however, the air was too much turbulent. Rather than take unnecessary risks, the pilot wisely decided to postpone the attempt.
The next day, 4 August, at 4.30 a.m., taking advantage of the fact that the air was cooler and calmer, at first daylight Jay Demming took off and after passing the peaks surrounding Lake Benson in 36 minutes reached the spot where the boy was. In a short time the latter was placed in the cabin. Demming in order to lighten the Hiller 360 as much as possible, after starting the engine, got rid of the battery and excess fuel. Using all the available power, he took off again. 22 minutes ‘Kayo’ was at White Wolf Lodge where an ambulance was waiting to take him to the hospital.
The rescue carried out at Benson lake received considerable newspaper coverage, which helped to boost sales of the Hiller 360. That was the first historic direct confrontation in the skies between the UH-12 and Bell 47 series.