StopRotor Hybrid RotorWing for DARPA X-Plane Project

[hesham]

Hi,

How do you get high-speed, efficient performance from a hybrid rotorcraft design? The U.S. Defense Advanced Projects Agency (DARPA) is looking for organizations to help answer that question as part of its vertical takeoff and landing(VTOL) X-Plane program, and an Australian company is suggesting one possibility for the 52-month effort that has a budget of around $130 million.

StopRotor Technology, based in Sydney, is putting forth its Hybrid RotorWing, which the company says can fly as either a helicopter or fixed-wing aircraft.

Central to the aircraft’s design is the stop rotor technology, which switches between rotary and fixed-wing “in a manner previously unexplored in the history of VTOL development,” the company claims. All previous stop rotor designs have either sought to stop the rotors during forward flight or proposed an “impractical fuselage layout.”

StopRotor Technology is currently undergoing proof of concept prototype testing using computer simulations and flying models. While the Hybrid RotorWing is still in the development phase, the company plans to contact DARPA’s X-Plane program manager, Ashish Bagai. Whether the concept is a fit for the program or not, StopRotor Technology envisions that the aircraft “could fulfill a useful role in the rapidly expanding UAV [unmanned aerial vehicle] industry.”


The company is also looking for partners in the DARPA program. Spokesperson Deanne Watkins noted that, “we are keen to discuss collaborative proposals with leading innovative aerospace companies.

http://www.aviationtoday.com/rw/public-service/government-agencies/StopRotor-Technology-Submits-Hybrid-RotorWing-for-DARPA-X-Plane-Project_78998.html#.UbmzG05Yu-A

 

[sferrin]

Boeing X-50, Sikorsky X-Wing, etc. etc. etc.

 

[hesham]

That's right my dear Sferrin.

 

[ouroboros]

Certainly it's a novel solution well suited to UAV's, but a manned CRW using this rotor stop method would be one hell of a rollercoaster ride...

 

[Jemiba]

We had something very similar here http://www.secretprojects.co.uk/forum/index.php/topic,18556.msg178561.html#msg178561

 

[hesham]

We had something very similar here http://www.secretprojects.co.uk/forum/index.php/topic,18556.msg178561.html#msg178561

Yes my dear Jemiba,


but I think this concept is not good in vibrations or stability for the aircraft,am I right ?.

 

[GTX]

Maybe I am missing something here but what exactly is the “manner previously unexplored in the history of VTOL development"?

 

[Jemiba]

Probably it is meant, that transition is more tricky, then with most other concepts.
To my opinion, with those quite small fixed wings, forward speed would have to be quite
high with the rotor still rotating, or a considerable loss of height would have to be accepted
during transition. That would make the use like a helicopter at least difficult, I think.

 

[hesham]

Probably it is meant, that transition is more tricky, then with most other concepts.
To my opinion, with those quite small fixed wings, forward speed would have to be quite
high with the rotor still rotating, or a considerable loss of height would have to be accepted
during transition. That would make the use like a helicopter at least difficult, I think.

I agree with your opinion my dear Jemiba,


but may be in the near future we will find the perfect VTOL concept.

 

[ouroboros]

That's why I made the rollercoaster comment. This appears to use a deliberate stall like maneuver to buy time to transition the rotor mode in the flow stream, rather than trying to shift lift to other surfaces to unload then stop the rotor while in normal forward flight.

 

[Grey Havoc]

Looks like it didn't make the final cut: http://breakingdefense.com/2015/01/its-a-bird-its-a-plane-no-its-aircraft-that-flies-like-a-bird/

...In a selection scheduled for next October, DARPA will choose one company to build the VTOL X-Plane and flight test it in 2017-18. All the contenders are offering unmanned aircraft, which are easier to build because they require no cockpit, and in theory can substitute fuel or payload for cockpit and crew weight. The entrants, some or all of whom are investing their own money in addition to receiving cash from DARPA in the $130 million program, are:

Karem Aircraft’s TR36XP, a tiltrotor using company owner Abraham Karem’s patented Optimum Speed Tiltrotor (OSTR) technology, which reduces the
revolutions per minute of a rotor in forward flight and certain other conditions to get greater fuel efficiency and
less drag. Karem, who inaugurated the age of endurance unmanned aerial vehicles by inventing a series of drones culminating in the unarmed version of
the Predator, is developing a range of OSTR tiltrotors in various sizes for both military and civilian purposes.

Boeing Co.’s Phantom Swift, a monoplane that has tilting ducted fans on its wingtips, where the rotors are on the V-22 Osprey, and ducted lift fans in the
fuselage, akin to the mid-fuselage lift fan in the F-35B, the vertical takeoff version of the Joint Strike Fighter built
by Lockheed Martin. Boeing has built and flown a scale model 17 percent the planned size of the Phantom Swift’s wingspan of 50 feet and fuselage length of
44 feet nose to tail.

Sikorsky and Lockheed Martin’s Skunk Works, offering a “tail sitter” aircraft not yet fully described but called the Unmanned Rotor Blown Wing Concept.
Manned tail sitters attempted in the 1950s to meet the VTOL challenge failed, partly because it was difficult for pilots to
take off lying on their backs and land looking over their shoulders as if parallel parking. The Sikorsky-Lockheed concept, being unmanned, may work better
for that reason alone.

Aurora Flight Sciences Corp., founded and run by award-winning aeronautical engineer and human-powered flight promoter John S. Langford, is offering
perhaps the most exotic machine. The Aurora design is still under wraps, but according to a company news release will employ distributed electric propulsion,
“high-power and torque-density permanent magnet synchronous motors,” and autonomous flight control systems.