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Rotorcraft Pioneers V - Charles H. Kaman

Posted 12 years 26 days ago ago by Admin

By Brad McNally, Contributing Editor - An essential characteristic of anyone starting out in a new venture is determination and no one in the rotorcraft industryCharles Kaman better exemplifies this than Charles Kaman.  In the mid 1940s, working in the emerging helicopter industry with an unproven idea and little financial support, he was able to persevere despite many challenges and establish a successful helicopter company.  The hard work of the team that he assembled led to major advancements in helicopter design and the development of several successful production helicopter models.  Largely due to his determination, the company he founded still exists today with a long list of impressive accomplishments.


Charles Kaman was born in Washington, DC in 1919.  From a young age he had aspirations to be a pilot.  However, at the age of eight he was told by his family doctor that due to the loss of hearing in one ear, which had been caused by an infection from a tonsillectomy when he was four, he would not be able to be a pilot and would instead be an aeronautical engineer (Kaman, 1985).  He excelled in school and true to the doctor’s word began building model airplanes out of balsa wood and tissue paper for a school sponsored competition.  In high school, one of his rubber band motor powered models set a world endurance record.  From his model building experience he gained great insight into the importance of propeller design on aircraft performance.  After graduating from high school he enrolled in Catholic University where he majored in aeronautical engineering, graduating number one in his class.  After graduation he took a job with Hamilton Standard in East Hartford, CT.  His first assignment was in the propeller performance section of the aerodynamics division. 

Charles Kaman became attracted to helicopters after witnessing the flight of a Sikorsky helicopter in nearby Bridgeport, CT.  When Hamilton Standard formed a new department to do design work for Sikorsky in 1943, Charles was selected to head up the aerodynamics (Kaman, 1985).  While working for Sikorsky, he became interested in reducing helicopter control forces and increasing stability.  This was not part of his assignment, so he worked on the problem on his own time and eventually developed his patented servo flap control system.  Unlike most helicopters, which change blade pitch by rotating the entire length of the blade at the blade root, the servo flap control system uses a small aileron type wing attached roughly three quarters of the way out on the trailing edge of the blade to fly the blade into position.  Changing the blade pitch at the root takes strong control forces which often require hydraulic assistance and create large flight control loads and strong vibrations.  The servo flap control system only requires small control forces to move the relatively small servo flap, the flap then moves the rest of the blade eliminating the need for strong control forces and decreasing the large loads on the flight controls and vibration levels.  This was a kaman helicopterradical idea and in order to get any support for it he would need data and lots of it.  Charles Kaman knew that he needed to develop a test rig to collect data but with World War II going on he was unable to obtain the necessary materials.  After exhausting several avenues and setting himself up as the Kaman Aircraft Laboratory, he was able to get the War Production Board to grant him priority status; effectively giving him the ability to purchase all the necessary materials to construct his rotor head (Kaman, 1985).  To build the test stand he bought a 1933 Pontiac from a junk yard and a found a Dodge truck rear axle from which he created a towable trailer with the Pontiac engine as the power plant and the upright Dodge rear axle as the transmission.  A $1.75 piece of spruce was used for the rotor blades, a standard bathroom scale was added to measure lift and testing began.  All of the testing was done at night or on the weekends and after many trial and error corrections Charles Kaman had collected enough data to present his ideas to the engineering management at the Hamilton Division of United Aircraft.  Unfortunately, they were not impressed and denied his request for a place to further develop his ideas and a technician to assist him.  His determination to see his idea become a reality led him leave and found his own company.  So it was, a promising five year career as an aerodynamicist at one of the most reputable helicopter companies of the day was now over and he had no idea what the future would hold.  Only his hard work and determination would get him through the days and months ahead.


With $5000.00 of equipment and two $1000.00 loans from his friends, the Kaman Aircraft Corporation was started in 1945 by then 26 year old Charles Kaman.  He was all too aware that one of the major problems plaguing helicopters of the day was a lack of power.  He decided to pursue the intermeshing rotor system as a means to increase the power available for lift by eliminating the power requirement of the tail rotor.  With the intermeshing rotor head and the servo flap control system in hand, the small but dedicated staff of the Kaman Aircraft Corporation set about to develop their first helicopter.  Money was tight and the first employees worked in the West Hartford garage of Charles Kaman’s mother.  Charles Kaman was not only intimately involved in design and construction but also worked tirelessly to find investors for the fledgling company.  He knew that he had a devoted and capable staff but without new investors they wouldn’t survive long enough to get a helicopter in the air.  Their first breakthrough came in 1947 when the K-125 made its first flight.  This single seat, piston powered helicopter had finally given Kaman Aircraft a product, but unfortunately it wasn’t able to sell it.  Due to several recent aviation accidents the Civil Aeronautics Authority (CAA) had instituted new certification requirements that would total nearly $500,000.00 to complete.  The company simply did not have the money to quickly obtain certification and several previously eager investors declined to support them.  Crop dusting was found to be one area where full certification was not required and the Kaman staff set to work to develop an improved version of the K-125 the K-190.  To say money was tight would be an understatement.  Many of the original employees worked for stock in the company and on weekends barnstorming sessions were held to attract potential investors from the local area.  Finally, the K-190 received CAA certification in April of 1949 and another larger more powerful version, the K-225, was certified later that year.  Unfortunately the crop dusting market along with domestic and foreign sales did not progress as hoped.  A total of only eleven K-225s were produced, one of which was sold to Turkey and became the first helicopter to fly in that country (Kaman, 1985). 


Largely due to his persistence and resolve Charles Kaman had been able to sell three K-225s to the military, two to the Navy and one to the Coast Guard.  While not a sizeable contract even in the 1940s, this at least kept the company going for a short while and got their foot in the door to military sales.  In 1949 the Marine Corps was looking for an observation helicopter and Kaman Aircraft submitted the HOK-1 as their proposal.  The Navy was impressed enough with it to place an order for four helicopters in 1950.  From this order was born what would arguably be Kaman’s most successful line of helicopters, the H-43.  Over 400 H-43 aircraft, including several variants, were produced between 1951 and 1967.  Starting with the HTK-1 (later redesignated as TH-43E), a Navy trainer version, and the HOK-1 (later redesignated as OH-43) for the Marine Corps, production extended to the HUK-1 (later redesignated as UH-43C), a Navy utility version (Mutza, 1998).  In 1952, Kaman Aircraft modified an HTK to be flown via remote control for a Navy funded program.  This project grew out of Charles Kaman’s vision for an unmanned aerial vehicle anti-submarine warfare program and was some of the earliest work done in the unmanned aerial vehicle field.  Although the Marine Corps and Navy were the first to use the H-43, it would have its greatest success with the Air Force.  In 1956, the Air Force was lookingkaman pic2 for a helicopter to fill its local base rescue mission.  This was to be primarily a rescue and recovery aircraft and one requirement was the ability to transport a crew and equipment to fight an aircraft fire.  Kaman submitted a proposal for an H-43 variant and won the contract for the H-43A, later known as the Husky.  Like its predecessors the H-43A was piston powered but that would change.  On 11 December, 1951 a K-225 equipped with a Boeing 502-2 gas turbine engine became the first helicopter to fly using gas turbine power.  The Kaman engineers were able to apply this new development to the H-43 line and in the late 1950s the H-43B, powered by a 825 hp Lycoming T53-L-1A gas turbine engine, went into production.  With this change, Kaman Aircraft became the first major helicopter manufacturer to switch production completely to turbine powered aircraft.  In 1961, an H-43B became the first helicopter to fly with composite rotor blades and the popularity of wooden rotor blades began to decline industry wide.  Over 200 H-43B helicopters were built and several demonstrated their capabilities by establishing helicopter records for altitude, time to climb and distance traveled.  In 1961 alone, an H-43B set an Altitude Without Payload record of 32,840 feet and later that same year set time to climb records for 9,842 feet in 2 minutes and 41.5 seconds, 19,684 feet in 6 minutes and 49.3 seconds and 29,426 feet in 14 minutes and 30.7 seconds (Mutza, 1998).  One final variant, the H-43F was produced and saw extensive action with the Air Force in an air rescue role during the Vietnam War.  Although not known for its speed, the H-43 did earn a reputation as a workhorse, capable of handling a variety of missions with outstanding performance at high altitude and dependability in aircraft firefighting and combat search and rescue roles.


With the H-43 series Kaman Aircraft had firmly established itself in the helicopter industry.  So in 1956, when the Navy was looking for a new utility helicopter that would expand the limits of current helicopter capabilities, Kaman was confident that they could compete with Sikorsky, Bell and Vertol.  Kaman Aircraft actually submitted two proposals for the Navy solicitation, one with intermeshing rotors and one of the main rotor and tail rotor configuration, both had the servo-flap control system.  The Navy selected Kaman’s main rotor and tail rotor configuration and in 1959 the HU-2 Seasprite made its first flight.  Later redesignated the UH-2 or SH-2, the Seasprite was one of the most technologically advanced helicopters of its time.  It combined a robust navigation package with anti-ice capability, a hull capable of water landings and a finely tuned rotor system allowing speeds up to 165 miles per hour while minimizing vibration levels (Kaman, 1985).  The UH/SH-2 series saw numerous upgrades over the years with many of the earlier models being converted to newer configurations.  The original single gas turbine design was later upgraded to dual gas turbines, which were in turn upgraded to more powerful engines.  In 1970 the Seasprite was selected by the Navy to be the platform for the Light Airborne Multi-Purpose System or LAMPS Mark I.  LAMPS used a helicopter to provide anti-submarine warfare capabilities to naval ships.  The LAMPS Mark I requirements evolved into the “F” series Seasprite.  The Seasprite series entered U.S. Navy service in 1962 and continued as an active airframe until the last Super Seasprite was retired by the U.S. Naval Reserve in 2001.  Over 250 Seasprite airframes, of several variants, were built and it is still being flown by several foreign militaries.


In the early 1990s the Kaman Corporation embarked on a private venture to create an affordable helicopter that could specifically fill the need for an “aerial truck”.  The result was the K-Max, an intermeshing rotor head aircraft with servo flap controls, powered by a single 1,800 horsepower gas turbine engine.  The K-Max made its maiden flight in December of 1991 and proved capable of lifting over 6,000 pounds, which is more than its own empty weight (Mutza, 1998).  Over 35 K-Maxs have been built, with many finding homes in the logging and construction industries.  They have even been used by the U.S. Navy for vertical replenishment operations.  In February of 2010, Kaman Aerospace partnered with Lockheed Martin to demonstrate the resupply capabilities of an unmanned K-Max for the U.S. Marine Corps.  A remotely piloted K-Max delivered several external loads via both preprogrammed flight plans and manual remote control (Team K-Max, 2010).

Over the years Charles Kaman has received numerous honors and awards including the Aviation Week and Space Technology Laureate Award, Wright kaman pic3Brothers Memorial Trophy, United States Medal of Technology and Department of Defense Distinguished Public Service Medal.  He is also a past president of the American Helicopter Society and a member of the U.S. Naval Aviation Hall of Honor, National Inventors Hall of Fame and honorary fellow of the Royal Aeronautical Society.  An avid musician, in 1966 he developed the Ovation Guitar by using his company’s superior aeronautical expertise to create a new guitar made of composite materials with a rounded back that had excellent sound transmission qualities.  Over the years Ovation Guitars have been played by such music greats as Mick Jagger, Jimmy Page, Shania Twain and Jon Bon Jovi just to name a few and the Kaman Music Corporation has become an industry leader in its own right (Cruice, 1996).  Charles Kaman and his wife Roberta also bred a new line of German Shepherds and founded the Fidelco Guide Dog Foundation.  Absent in Fidelco German Shepherds are some typical problems associated with the breed and they are trained to be excellent seeing eye dogs.  The company that Charles Kaman founded as Kaman Aircraft Corporation in 1945 now exists as the highly diversified Kaman Corporation, a former Fortune 500 company with over 4,000 employees worldwide (Kaman Website, n.d.).  One of its subsidiary groups, Kaman Aerospace, is a leader in specialty bearings, composite components and sensors for some of the world’s largest aircraft manufacturers and the military.  True to its roots, the Kaman Corporation still has its headquarters in Bloomfield, CT and Kaman Aerospace has a Helicopter Division that manufactures and supports the Seasprite and K-Max platforms.

Driven by an undying determination, Charles Kaman and the company he founded persevered against insuperable odds.  His resolve allowed him to successfully develop the innovative servo-flap control system and perfect the intermeshing rotor head.  Both of which are trademarks of Kaman Helicopters that are still evident in models that are flying over 60 years later.  With developments such as the first turbine powered helicopter, first helicopter with all composite rotor blades and pioneering remotely piloted helicopters, his company earned a reputation as a technological front runner with a superb engineering and development team.  The H-43 became a highly successful line of helicopters known for their extraordinary ability to work at altitude and capability to handle a variety of missions in some of the most demanding arenas that helicopters have ever been operated in.  Charles Kaman’s fortitude combined with his innovation and remarkable business sense allowed him to leave a mark on the rotorcraft industry that few have equaled, making him a true Rotorcraft Pioneer.


Cruice, V. (1996, December 8). From the Ratcheting of Helicopters to a Guitar’s Hum. New York Times. Section 13CN, Page 2.

Kaman, C. H. (1985). Kaman: Our Early Years. Indianapolis, IN: The Curtiss Publishing Company Inc.

Kaman Website. (n.d.). Retrieved March 17, 2010, from http://www.kaman.com

Mutza, W. (1998). Kaman H-43: An Illustrated History. Atglen, PA: Schiffer Publishing Ltd.

Team K-Max Demonstrates Successful Unmanned Helicopter Cargo Resupply to U.S. Marine Corps. (2010, February). Kaman Aerospace Website. Retrieved March 17, 2010 from http://www.kamanaero.com/news.html