Type: vertical/ultra-short take-off and landing transport
Program: Darpa Heliplane (and possibly USAF CSAR-X/PRV)
Powerplant: 2 x 13.34kN (3,000 lb. st.) Williams International FJ44 turbofans
Significant date: 2005 (contract issued)
Small business qualifier Groen Brothers Aviation (GBA) in Salt Lake City, Utah, are well-known for their advocacy of and experience with gyrodyne technology. Gyrodynes use tip-acceleration to spin rotors for vertical or USTOL (Ultra-Short Take Off and Landing) takeoff and initial flight, then switch to conventional wings and propellers and place the heliblades in autorotation. Hovering capability is limited with gyrodyne designs, but vertical landing is achieved through this autorotation and works even without power. GBA had some success with their Hawk 4 model. In 2005, GBA participated in but lost a bid for a Joint Heavy Lift concept design contract with their GyroLifter concept, which planned to use the Lockheed C-130 airframe and technology as a basis — GBA had even converted a Cessna Skymaster by clipping its wings and installing the rotor from the Hawk 4 in order to demonstrate the concept of converting an existing aircraft to a gyroplane.
The same year, however, GBA were granted another gyroplane contract with DARPA. The Defense Advanced Research Projects Agency (DARPA) planned to demonstrate a 400 mph gyrodyne, called the Heliplane — a proof of concept high speed, long range air vehicle that combines vertical take-off and landing (VTOL) and the low disk loading characteristics of a helicopter with the speed and efficiency characteristics of a fixed wing aircraft. A gyrodyne has a rotor that is driven for take-off, hover, and landing, but auto-rotates in forward flight. In the Heliplane, the rotor is powered by tip-jets. Air is ducted from the engines, mixed with fuel, and burned at the tips of the rotor blades. The same engines provide thrust for forward flight. The rotor blades are of course made of advanced airfoil composite materials.
DARPA’s Heliplane program has set itself the goals of designing, developing, and flight testing an air vehicle that combines the vertical take-off and landing (VTOL) and low disk loading characteristics of a helicopter with the speed and efficiency characteristics of a fixed wing aircraft. Noise limitation is also an issue, as tip-jet noise has always proved a challenge. The Heliplane program will conduct a combination of analysis and experiments to develop and demonstrate key enabling technologies. Once key enabling technologies have been demonstrated, a preliminary design of the Heliplane system will be completed, a test of the rotor system will be conducted to demonstrate that the rotor is stable in high-speed flight, detailed design will be completed, and a Heliplane demonstrator will be fabricated and flight tested.
As a first stage in the Heliplane program, DARPA funded Boeing's Canard Rotor Wing (CRW) prototypes (designated as X-50A Dragonfly), while issuing a solicitation in Federal Business Opportunities on February 16, 2005 for another demonstrator, with proposals being received from multiple companies, including Challis Heliplane, Carter Aviation Technologies (CarterCopter) and Groen Brothers Aviation. GBA claimed that use of powered rotors for short-term hovering/takeoff and main engines for forward thrust eliminated the need for much of the cost, weight, and complexity found in helicopters, while permitting much higher forward speeds and creating additional safety from the blades’ natural autorotation in forward flight. This also made their vehicles somewhat attractive for the US Air Force CSAR-X/PRV contract. Indeed, according to DARPA’s plans, the Heliplane demonstrator aircraft would be suitable for combat search and rescue (CSAR) missions, boasting a 400 mph cruise speed, a 1,000 lb payload, and an unrefueled range of 1,000 miles.
Groen Brothers Aviation's experience with gyrodyne technology enabled them to win the contract in November 2005. Phase One of GBA's potentially multi-year, $40 million, 4-phase DARPA award began with a 15-month, $6.4 million award to develop the preliminary design and perform key technology demonstrations (with a $3 million increment to get started). Meanwhile, the USAF was looking at competition in the FY 2006 timeframe in order to have the PRV contract awarded by the end of 2006 if possible. Heliplane also received support from NASA’s Ames Research Center and the U.S. Army’s Aero-Flight Dynamics Directorate there. “We have taken a 40-year-old concept and revived it,” says program manager Don Woodbury from DARPA. “We will see if we can advance VTOL with the Heliplane,” he says “If we can get performance out of a rotary wing that is comparable with a fixed wing in speed and efficiency we will change the nature of VTOL. It could be the birth of a new age of rotary-wing aviation.”
GBA’s team included : 1°) the Georgia Institute of Technology (GIT or Georgia Tech), whose Center of Excellence in Rotorcraft Technology has done extensive research on the gyrodyne concept; 2°) Adam Aircraft Industries, known for its innovative use of modern composite materials and rapid prototyping processes that had allowed Adam to bring to market two new high-performance aircraft (the six passenger “center-line-twin” A500 and the A700 personal jet); 3°) Williams International, who developed more than 40 different small gas turbine engine systems for both military and commercial air vehicles, including the Adam A700 and other modern business jets; and finally 4°) a team of aerospace consultants and researchers from Washington University in St. Louis, Pennsylvania State University and the University of Maryland.
GBA’s work was to be performed in Salt Lake City, UT (70%); Atlanta, GA (20%); Walled Lake, MI (5%); and Englewood, CO (5%); and was expected to be complete in January 2007. Adam Aircraft was meant to provide the all-composite airframe of the Heliplane based on their A700 model. Unfortunately the short-lived company soon went out of business. Adam’s collapse came as Heliplane project officials were concluding that they were better off working with a newly designed airframe instead of a modified one, according to a top DARPA executive. That confluence led to the project hiring Scaled Composites to build its baseline aircraft. Worthy of notice is the fact that Scaled Composites had designed the Adam family of aircraft from the start (see Model 309). At that point Groen Brothers Aviation was the prime contractor, but eventually they too ran into financial problems. Although GBA was given a six-month extension to its Phase One contract to study alternative tip-jet designs, Groen was not able the meet the tip-jet noise goals of the heliplane program.
The program gained a new lease of life after Georgia Tech, who played a key role in Phase 1A studies and provided GBA with much of its “analytical horsepower”, took over the prime position. GBA continued to work on the rotor and rotor hub. DARPA expects GBA to be a subcontractor to Georgia Tech on Phases 1B and 2 of the program. As expected, the six-month Phase 1B will focus on maturing the design of a rotor capable of meeting the 400 mph speed and tip-jet noise objectives. The Georgia Tech team will work to meet all program objectives, including tip-jet noise requirements. The goal is to create a rotorcraft that can take-off and land vertically and cruise twice as fast as any conventional helicopter.
Georgia Tech's contract will also cover follow-on Phase 2, in which it will be required to "complete an experimental demonstration of the capability to control the Heliplane at cruise speeds up to 400 mph and to demonstrate the capability to meet tip-jet noise goals". That's almost twice what its British ancestor, the venerable Fairey Rotodyne, once achieved in the late 1950s, and also twice the speed of its US contemporary, the McDonnell's XV-1 Convertiplane. Georgia Tech will conduct a subscale windtunnel demonstration of the ability to control the rotor at 400 mph. Stabilizing an unloaded, autorotating rotor at speeds that high is a key challenge of the Heliplane program. Georgia Tech will also perform a cold-flow test of a full-scale tip-jet nozzle, being among a group of universities that have been involved in some interesting work on noise-suppressing distributed nozzles.
According to Aviation Week & Space Technology, "DARPA is scaling back ambitions for the Heliplane gyroplane program while taking a closer look at another high-speed rotorcraft concept." According to AW&ST, "it looks likely a flying demonstrator is no longer on the cards" as DARPA is now looking at the high-speed DiscRotor concept as well as starting up a morphing-rotor program. DARPA has even awarded Boeing (who was already contributing the X-50 Dragonfly for the agency's Heliplane program) a $7.35 million contract for Phase 1 of the DiscRotor risk-reduction study. DARPA program manager Don Woodbury, however, gave a conference on the Heliplane as recently as May 2009, perhaps indicating that the program has not been shelved yet. "It is hard to see why the Rotodyne did not progress. It was revolutionary back then and, if it was flying today, it would be at the top end of rotorcraft performance."
Population: none built
Crew/passengers: probably 2 crew / 6 pass.
More on the Groen Brothers
Before Jay Groen (left) and his brother David (right) formed Groen Brothers Aviation (or GBA in short), they had co-founded the Seagull Recycling Company, an organization that developed an original supply of secondary paper fiber for sale to domestic and Far East markets. GBA was then founded in 1986 with the goal of re-discovering and developing the science of autorotative flight used by gyroplanes and gyrodynes. By 2001 they had grown GBA’s staff to more than 130 people, they had flown the world’s first turbine-powered gyroplane, the GBA Hawk 4, and were proceeding toward FAA commercial certification of that aircraft.
David’s continuing emphasis on exploiting the huge potential of the technology of autorotative flight gained the company quick recognition. As early as 2002, the Aerospace Industries Association in their summer Executive Report of that year stated that, “What the Wright Brothers did for the airplane 100 years ago, the Groen Brothers are doing for the gyroplane today.” By that time, the Company had initiated the development of its light gyroplane, the SparrowHawk, which has established new safety and performance standards for both personal and public use of this type of aircraft. The Groen brothers also authored a best selling book entitled Huey, a novel about a helicopter pilot’s experiences in the Vietnam War.
GBA was saddened to announce in early October, 2006 the passing of Chairman Jay Groen at his home in Washington DC. Jay battled cancer for almost two years, a challenge he faced with his characteristic directness, determination, and humor. “Jay’s passing leaves a void within us all, but at the same time furthers our resolve to succeed in this endeavor to celebrate his dedication, devotion and persistence” said David Groen.