Bell Boeing Quad TiltRotor

Infobox Aircraft
name= Quad TiltRotor


caption= Bell Boeing Quad Tiltrotor concept
type= Cargo helicopter
manufacturer= Bell / Boeing
designer=
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retired=
status=Study
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The Bell Boeing Quad TiltRotor (QTR) is a proposed four-rotor derivative of the V-22 Osprey tiltrotor being developed jointly by Bell Helicopter Textron and Boeing Integrated Defense Systems. The concept is a contender in the U.S. Army's Joint Heavy Lift program. It would have a cargo capacity roughly equivalent to the C-130 Hercules, cruise at 250 knots, and land at unimproved sites vertically like a helicopter. [http://www.boeing.com/news/frontiers/archive/2006/december/i_ids03.pdf "Diversity in Design: Boeing offers 2 of 5 development options in rotorcraft program"] , Boeing Frontiers magazine, January 2007.]

Development

Bell and Boeing have received a cost-sharing contract worth US$3.45 million from the U.S. Army's Aviation Applied Technology Directorate for an 18-month conceptual design and analysis study lasting through March 2007, in conjunction with the Joint Heavy Lift program. [http://www.boeing.com/news/releases/2005/q3/nr_050922p.html "Boeing receives two study contracts from U.S. Army for Joint Heavy Lift"] , Boeing press release, 2005-09-23.] [http://boeing.com/news/releases/2005/photorelease/q3/pr_050923p-1.html Bell-Boeing's QTR selected for Heavy Lift study] ] The contract was awarded to Bell Helicopter, which is teaming with Boeing's Phantom Works. The QTR study is one of five designs; another of the five is also a Boeing program, an advanced version of the CH-47 Chinook.

During the initial baseline design study, Bell's engineers are designing the wing, engine and rotor, while the Boeing team is designing the fuselage and internal systems.Fein, Geoff. [http://www.accessmylibrary.com/coms2/summary_0286-25440284_ITM "Bell-Boeing Quadtiltrotor completes first wind tunnel testing"] , "Defense Daily", 2006-10-13.]

A one-fifth-scale wind tunnel model has undergone testing in the Transonic Dynamics Tunnel (a unique transonic wind tunnel) at NASA's Langley Research Center during summer 2006. The "semi-span" model (representing the right half of the aircraft) measured 213 inches in length, and had powered 91-inch rotors, operational nacelles, "dynamically representative" wings. [http://www.helis.com/news/2006/quadwindtunnel.htm "Wind Tunnel testing completed on Bell Boeing quad tiltrotor"] , Helis.com, September 13, 2006.]

The primary test objective was to study the aeroelastic effects on the aft wing of the forward wing's rotors and establish a baseline aircraft configuration. Alan Ewing, Bell's QTR program manager, reported that "Testing showed those loads from that vortex on the rear rotor [are the] same as the loads we see on the front [rotors] ," and "Aeroelastic stability of the wing looks exactly the same as the conventional tiltrotor". These tests used a model with a three-bladed rotor, future tests will explore the effects of using a four-bladed system.

Besides the research performed jointly under the contract, Bell has funded additional research and wind tunnel testing in cooperation with NASA and the Army. [http://www.bellhelicopter.com/en/support/pdf/rb/rb_oct06.pdf "Wind Tunnel testing completed on Bell Boeing quad tiltrotor"] , "Rotorbreeze", p. 14, October 2006.] After submission of initial concept study reports, testing of full-scale components and possibly a sub-scale vehicle test program was expected to begin. Pending approval, first flight of a full-scale prototype aircraft was slated for 2012.

The study was completed in May 2007, [ [http://www.flightglobal.com/articles/2008/01/14/220796/heavy-duty-us-army-backs-tiltrotor-as-future-battlefield.html "Heavy duty: US Army backs tiltrotor as future battlefield airlifter"] , Flight International, 14 January 2008.] with the Quad TiltRotor selected for further development. However, additional armor on Future Combat Systems (FCS) vehicles caused their weight to increase from 20 tons to 27 tons which requires a larger aircraft. [Osborn, Kris. [http://www.defensenews.com/story.php?i=3482732&c=FEA&s=CVS "USAF, Army Merge Heavy-Lift Efforts"] , Defensenews.com, 14 April 2008.] In mid-2008, the Army continued the Joint Heavy Lift (JHL) studies with new contracts to the Bell-Boeing and Karem Aircraft/Lockheed Martin teams. The teams are to modify their designs to reach new JHL specifications. JHL became part of the new US Air Force/Army Joint Future Theater Lift (JFTL) program in 2008. [Warwick, Graham. [http://www.aviationnow.com/aw/generic/story.jsp?id=news/JHL070108.xml&headline=U.S.%20Army%20Extends%20JHL%20Concept%20Studies&channel=defense "U.S. Army Extends JHL Concept Studies"] , Aviation Week, 1 July 2008.]

Design

The conceptual design is for a large tandem wing aircraft with V-22 type engines and 50-foot rotors at each of the four wing tips. The C-130-size fuselage would have a 747-inch-long cargo bay with a rear loading ramp that could carry 110 paratroopers or 150 standard-seating passengers. In cargo configuration, it would accommodate eight 463L pallets.

In addition to the baseline configuration, the Bell-Boeing team is including eight possible variants, or "excursion designs", including a sea-based variant. The design team is planning on payloads ranging from 16 to 26 tons and a range of 420 to 1000 nm. The baseline version includes a fully retractable refueling probe and an interconnecting drive system for power redundancy.

One of the design excursions explored by the team, dubbed the "Big Boy", would have 55-foot rotors and an 815-inch-long cargo bay, making it able to carry one additional 463L pallet, and accommodate a Stryker armored combat vehicle.

ee also

aircontent
related=
* V-22 Osprey

similar aircraft=
* Bell X-22
* Curtiss-Wright X-19

lists=
*List of military aircraft of the United States
*List of VTOL aircraft

see also=
* Quadrotor
* Tiltrotor
* Powered lift

References

External links

* [http://www.popularmechanics.com/science/defense/1281266.html V-44: Pentagon's Next Air Transport] , "Popular Mechanics", September 2000
* [http://www.globalsecurity.org/military/systems/aircraft/qtr.htm Quad Tiltrotor QTR page on GlobalSecurity.org]
* [http://www.vtol.org/vertiflite/BellTiltrotors.htm Bell Tilt Rotors on VTOL.org]
* [http://www.defenseindustrydaily.com/2005/09/ch53x-hlr-jhl-future-heli-programs-on-collision-course/index.php "CH-53X HLR & JHL: Future Heli Programs on Collision Course?", "Defense Industry Daily", 2005-09-27]
* [http://www.dallasnews.com/sharedcontent/dws/bus/stories/082406dnbusquadtiltrotor.2f76857.html Bell and Boeing working on quad tilt-rotor design] , "Dallas Morning News", 2006-08-24
* [http://www.flightglobal.com/articles/2007/10/09/217956/us-army-looking-at-three-configuration-concepts-for-large-cargo-rotorcraft.html "US Army looking at three configuration concepts for large cargo rotorcraft"] , Flight International, October 9, 2007