Bell Boeing Quad TiltRotor
The Bell-Boeing Quad Tiltrotor (QTR) is a concept for a four-engine tilt rotor aircraft as part of the US Army's "Joint Heavy Lift" program . This is at least partially a further development of the V-22 Osprey , which is intended to complement and replace the CH-47 and C-130 in a variety of tasks. Karem Aircraft and Lockheed Martin develop the Optimum Speed Tiltrotor as a competitor .
history
background
The quad tiltrotor concept can be traced back to the 1960s when the first flightable four-engine tilt rotor aircraft, the XC-142 , X-19 and X-22 , were tested. Neither of the two prototypes ever went into series production. In 1979 Bell once again ventured into a four-engine tilt rotor aircraft, with the D-322 model also failing. Only 20 years later there were serious plans to realize such a machine again. In 1999 Bell-Boeing offered the US Army a four-engine V-22 as part of the “Future Transport Rotorcraft” program. With a 50% component match to the V-22 , this model should have a payload of 11 t with a maximum take-off weight of 45 t. The design, designated by Bell-Boeing as V-44 (the designation was never adopted by the US armed forces), was later reduced in its payload several times in order to achieve an even better match with the V-22. In 2000 Bell tried to get a development contract, but the US Army did not support this concept in the end.
Studies
Work on the actual QTR concept did not finally begin until September 2005, when Bell-Boeing delivered a 3.45 mil. US $ development contract received from the US Army to develop a concept study for a possible replacement of the CH-47 Chinook and C-130 Hercules . The contract ran for 18 months and the results were available in March 2007. The QTR was the content of one of a total of five studies, with the remaining four all being carried out by Boeing alone and dealing with improved versions of the CH-47. For the QTR, Bell took on the design of the wings, motors and rotors. Boeing's team took care of the rest of the components, including a. the entire internal systems ( avionics etc.). As with the “V-44”, both teams rely on a high level of component conformity with the V-22.
In summer 2006 a first wind tunnel model of the QTR was built on a scale of 1: 5 and tested at NASA Langley Research Center . The main part of these tests was the investigation of elastic deformation on the rear rotor blades caused by the turbulence of the front rotor blades. Three-blade rotors were used in these tests, and the results suggested that four-blade rotors would be used in further studies.
When the research results were available in May 2007, the QTR concept was selected for future developments; the alternative CH-47 developments were abandoned. When the vehicles of the " Future Combat System ", which has since been discontinued, increased to a weight of 20 to 27 t, the required payload of the QTR was adjusted accordingly. In the summer of 2008, the Army continued the studies as part of the "Joint Heavy Lift" program. To this end, new contracts were also concluded; one received Bell-Boeing, the other went to a consortium of Karem Aircraft and Lockheed Martin , who are developing the competing design " Optimum Speed Tiltrotor ", which is also known as "Joint Heavy Lift". The first prototypes were expected in 2012.
construction
In terms of design, the QTR is a four-engine tilt rotor aircraft in tandem configuration. At each end of the wing, a 50-foot four-bladed rotor of a propeller turbine Rolls-Royce is driven AE1107C. This is already used in the V-22. The dimensions of the cargo hold should correspond to those of a C-130 and be able to transport up to 90 to 110 paratroopers . Alternatively, eight 463L pallets can also be accommodated.
In the current conception phase, Bell-Boeing is examining several configurations, including: a. a sea-based variant or an enlarged model called a "Big Boy". This would use 55 foot rotors and have an elongated hull. This increases the payload to nine pallets or, alternatively, a Stryker vehicle .
Due to the different configurations, there are sometimes very different technical data in circulation. The payload varies from 16 to 26 t and the range from 420 to 1000 km. In the requirement profile of the Army, an internal payload of 15,000 kg is specified, an external of 20,000 to 22,000 kg. The range with maximum payload should be 1,000 km, while the transfer range is 4,000 km.
Web links
- Quad Tiltrotor QTR page on GlobalSecurity.org
- "CH-53X HLR & JHL: Future Heli Programs on Collision Course" . Defense Industry Daily , Sept. 27, 2005.
- "Bell and Boeing working on quad tilt-rotor design" ( Memento from April 27, 2009 in the Internet Archive ). Dallas Morning News , Aug. 24, 2006.
- "US Army looking at three configuration concepts for large cargo rotorcraft" . Flight International , October 9, 2007.