VTOL X-Plane

DARPA announced the programme in February 2013 with a requirement to create a new aircraft that uses the best features from both vertical take-off and landing technology and that used for conventional aircraft. The hybrid aircraft will try to improve on four areas:

• Speed - achieve a top speed of at least 300 kts.
• Hover - increase hover efficiency to at least 75 percent.
• Cruise efficiency - achieve a lift-to-drag ratio of at least 10.
• Load - ensure the solution can carry a useful load of at least 40% of the projected gross weight.

The first two companies to be involved were announced in December 2013 when Sikorsky Aircraft was awarded a US$14.4 million contract and Aurora Flight Sciences was given US$14 million for preliminary design studies as part of the $47 million Phase One budget.{{cite news|url = http://www.avweb.com/avwebflash/news/DARPA-Wants-400-Knot-VTOL221170-1.html|title = DARPA Wants 400-Knot VTOL|access-date = 26 December 2013|last = Niles|first = Russ|date = 23 December 2013| work = AVweb}}

On 18 March 2014, DARPA announced that Sikorsky, Aurora Flight Sciences, Boeing, and Karem Aircraft had been selected to compete for the VTOL X-plane. The four companies have based their designs on unmanned aircraft and will compete over the next 20 months. The name of Aurora's submission was revealed as the LightningStrike in February and although the design was unknown, the company has a history of producing ducted fan and hybrid propulsion aircraft. Karem Aircraft was expected to propose a tiltrotor aircraft with an optimum speed rotor. The Boeing PhantomSwift embedded twin lifting fans inside the fuselage with tilting ducted fans mounted on wingtips for lift and forward thrust; a scale demonstrator was built and flown by the company in 2013. Sikorsky teamed with Lockheed Martin for a "low complexity" design that combined fixed wing aerodynamics and advanced rotor control. A single design was to be selected in autumn 2015 for a $95 million contract{{cite web|url=https://nypost.com/2015/10/11/four-candidates-to-become-the-airplane-of-the-future/|archive-url=https://web.archive.org/web/20151011180919/http://nypost.com/2015/10/11/four-candidates-to-become-the-airplane-of-the-future/ |title=Competition is fierce to build the airplane of the future |author=Richard Whittle |archive-date=11 October 2015|work=New York Post |date=October 11, 2015 |access-date=11 October 2015 |url-status=live}} to build a demonstrator in phase 2.[http://www.flightglobal.com/news/articles/darpa-selects-four-bidders-for-high-speed-vtol-x-plane-397156/ DARPA selects four bidders for high-speed VTOL X-Plane] - Flightglobal.com, 18 March 2014

• Rotor Blown Wing - Sikorsky and Lockheed Martin teamed to develop their unmanned rotor blown wing concept. They claimed it integrated fixed wing aerodynamics and advanced rotor control to provide a low complexity configuration. An artist depiction of Sikorsky's Rotor Blown Wing bore visual resemblance to the Boeing Heliwing, an unmanned tailsitter intended to reach {{convert|180|knot|mph km/h|abbr=on}} in forward flight; it first flew in April 1995 but crashed in July and the project was shelved. Sikorsky confirmed that the Rotor Blown Wing would be a tailsitter, with its name suggesting that the wing remains aligned into the proprotor wash during transition between vertical and forward, reducing download on the wing in hover mode.[http://aviationweek.com/blog/sikorskys-rotor-blown-wing-look-familiar Sikorsky's Rotor Blown Wing -- Look Familiar?] - Aviationweek.com, 20 December 2013
• LightningStrike - Aurora Flight Sciences' LightningStrike would achieve high overall efficiency by integrating the propulsion into the air vehicle's aerodynamic design. The company has experience with ducted-fan designs through Goldeneye series aircraft, also under DARPA programs, and with hybrid-electric propulsion with the Excalibur unmanned aerial vehicle proof-of-concept aircraft to create a design providing vertical takeoff and landing with high-speed horizontal flight.[http://www.aurora.aero/Media/Press/Item.aspx?id=apr-312 Aurora Wins DARPA VTOL X-Plane Program Contract] - Aurora press release, 4 February 2014 Levering this experience Aurora Flight Sciences' developed a revolutionary vehicle concept that employs Electric Distributed Propulsion (EDP) in eighteen {{convert|31|in|cm|abbr=on}} wing fans, and six {{convert|21|in|cm|abbr=on}} canard fans, driven by 3 MW of electricity.
• Karem tiltrotor - Karem Aircraft submitted a tiltrotor concept called TR36XP, employing a slender-bodied fuselage with a high-aspect-ratio gull wing. The outer sections of the wing, together with two 36 ft rotor/propellers, rotated through 90 degrees for transition between hover and forward flight, powered by two Rolls-Royce Turbomeca RTM322.[http://www.ainonline.com/aviation-news/2014-03-19/darpa-awards-final-vtol-x-plane-contracts Darpa Awards Final VTOL X-Plane Contracts] - Ainonline.com, 21 March 2014
• PhantomSwift - Boeing's PhantomSwift concept had two large internal fans to provide lift with two wingtip fans that provide stability while hovering. In forward flight, the internal fans stop supplying power and the wingtip fans provide thrust. Boeing claimed that this configuration was 50 percent more efficient in the hover than a typical helicopter, and expected to have a top speed of {{convert|740|km/h|mph knot|abbr=on}}. The full-size version would have had a wingspan of {{convert|50|ft|m|abbr=on}}, a fuselage length of {{convert|44|ft|m|abbr=on}}, and weigh {{convert|12,000|lb|kg|abbr=on}}.[http://www.armedforces-int.com/news/boeing-phantom-swift-joins-vtol-x-plane-comp.html Boeing Phantom Swift Joins VTOL X-Plane Comp] - Armedforces-Int.com, 25 June 2014 The demonstrator would be powered by one or two General Electric CT7-8 engines, but a production version would be powered by an all-electric drive.{{usurped|1=[https://web.archive.org/web/20140829235105/http://defensetech.org/2014/08/28/boeing-gets-9m-more-to-develop-phantom-swift-x-plane/ Boeing Gets $9M More to Develop Phantom Swift X-Plane]}} - Defensetech.org, 28 August 2014

The design, development and integration phase is expected to last 18-months; Phase Two will allow companies to mature their designs.

On 3 March 2016, DARPA awarded Aurora Flight Sciences $89.4 million to build and demonstrate their LightningStrike concept, beating out the other three competitors. The LightningStrike is a tilting-wing design powered by one Rolls-Royce AE1107C turboshaft engine, the same type used on the V-22 Osprey, that generates electric power via three Honeywell generators to run 24 distributed ducted fans, three each in the forward canards and 18 across the main wing. Rather than using conventional engines like all the other entrants, the aircraft relies on "distributed electric propulsion," where the three generators that produce three megawatts (4,023 horsepower) of electricity, as much as a commercial wind turbine, power individual motors that drive the fans; each wing fan uses a 100 kW motor, and each canard fan a 70 kW motor. The air vehicle will weigh between {{convert|10000-12000|lb|kg|abbr=on}}, about the size of a UH-1Y Venom, and cruise faster than 300 knots, 50 knots faster than the V-22. Phase II of the VTOL X-Plane project will fabricate two air vehicles before flight testing, planned by September 2018.[http://www.defenseone.com/technology/2016/03/check-out-militarys-experimental-helicopter-plane/126432/?oref=d-river Check Out the Military’s Experimental Helicopter Plane] - Defenseone.com, 4 March 2016[http://breakingdefense.com/2016/03/you-aint-gonna-believe-this-design-wins-darpa-x-plane-deal-2/ You-Ain’t-Gonna-Believe-This Design Wins DARPA X-Plane Deal] - Breakingdefense.com, 4 March 2016[http://defense-update.com/20160303_vtol_x_plane.html DARPA Selects Aurora’s LightningStrike 24-prop Hybrid VTOL X-Plane] - Defense-Update.com, 3 March 2016[http://www.ainonline.com/aviation-news/defense/2016-03-06/aurora-wins-darpa-contract-build-novel-drone-demonstrator Aurora Wins Darpa Contract to Build Novel Drone Demonstrator] - Ainonline.com, 6 March 2016 A 20 percent-scale demonstrator, weighing 325 lb (147 kg) using wings and canards made of carbon composites and 3D-printed plastics, was flown on 29 March 2016.[https://www.flightglobal.com/news/articles/aurora-flies-subscaled-electric-vtol-demonstrator-424323/ Aurora flies subscaled electric VTOL demonstrator] - Flightglobal.com, 18 April 2016[http://www.gizmag.com/darpa-x-plane-flight-{{Not a typo{{!}}mina{{!}}ture}}/42867/ DARPA VTOL X-plane takes flight in miniature]{{Dead link|date=August 2024 |bot=InternetArchiveBot |fix-attempted=yes }} - Gizmag.com, 18 April 2016 The full-scale aircraft will be designated the XV-24A.[http://newatlas.com/darpa-xplane-vtol-successful-flight-test/48823/ DARPA’s sub-scale VTOL X-Plane prototype completes flight testing] - Gizmag.com, 5 April 2017

Phase Three was to last 12-months from February 2017 to February 2018 and consist of ground and flight tests of the experimental designs.

DARPA cancelled the project before flight testing.{{cite news |url= http://aviationweek.com/future-aerospace/darpa-pulls-plug-aurora-s-hybrid-electric-vtol-x-plane |title= Darpa Pulls Plug On Aurora's Hybrid-Electric VTOL X-Plane |date= Apr 24, 2018 |author= Graham Warwick |work= Aviation Week Network}}

{{reflist|refs=

{{cite web|url=http://www.darpa.mil/Our_Work/TTO/Programs/Vertical_Takeoff_and_Landing_Experimental_Plane_%28VTOL_X-Plane%29.aspx|title=Vertical Takeoff and Landing Experimental Plane (VTOL X-Plane)|access-date=22 December 2013|publisher=DARPA}}

{{cite web|url=http://www.flightglobal.com/news/articles/darpa-announces-new-x-plane-programme-382691/ |title=DARPA announces new X-plane programme|date=25 February 2013|publisher=Flightglobal|access-date=22 December 2013}}

{{cite web|url=http://www.flightglobal.com/news/articles/sikorsky-wins-contract-to-build-experimental-vtol-aircraft-394374/ |title=Sikorsky wins contract to build experimental VTOL aircraft|date=20 December 2013|publisher=Flightglobal|access-date=22 December 2013}}

Warwick, Graham. "[http://aviationweek.com/blog/high-speed-vtol-darpa-tries-again High-Speed VTOL -- DARPA Tries ... Again]" Aviation Week & Space Technology, 24 March 2013. Accessed: 25 May 2014.

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Category:DARPA projects

Category:2010s United States experimental aircraft

Category:VTOL aircraft