NEW DARPA VTOL X-Prize

bobbymike

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DARPA Experimental Aircraft Program to Develop the Next Generation of Vertical Flight February 25, 2013



Higher speeds, increased efficiency, elegant designs are the focus of new VTOL X-Plane
One of the greatest challenges of the past half century for aerodynamics engineers has been how to increase the top speeds of aircraft that take off and land vertically without compromising the aircraft's lift to power in hover or its efficiency during long-range flight.


The versatility of helicopters and other vertical take-off and landing (VTOL) aircraft make them ideal for a host of military operations. Currently, only helicopters can maneuver in tight areas, land in unprepared areas, move in all directions, and hover in midair while holding a position. This versatility often makes rotary-wing and other VTOL aircraft the right aerial platform for transporting troops, surveillance operations, special operations and search-and-rescue missions.


Compared to fixed-wing aircraft, helicopters are slower-leaving them more vulnerable to damage from enemy weapons. Special operations that rely on lightning-quick strikes and medical units that transport patients to care facilities need enhanced speed to shorten mission times, increase mission range, reduce the number of refueling events and, most important, reduce exposure to the adversary.


http://www.darpa.mil/NewsEvents/Releases/2013/02/25.aspx


https://www.fbo.gov/index?s=opportunity&mode=form&id=c57026779aee22558afd0c06ddee6404&tab=core&_cview=0
 
So I guess their Disc-Rotor has gone the way of the Heliplane already?
 
DARPA-VTOL-X-Plane1.jpg

Original Caption: Some of Darpa’s imagined designs for its new VTOL X-Plane program. Image: Darpa​

http://www.wired.com/dangerroom/2013/02/darpa-vtol-x/​
 
bobbymike said:
sferrin said:
So I guess their Disc-Rotor has gone the way of the Heliplane already?
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Still in DARPA's TTO 'Platform' section?
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Maybe its not "DARPA hard" any more :-\
 
Reaper said:
What happened to Darpas Flying VTOL Humvee?
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Well it does not do 300 Knots :p

Not sure but I think it died when the Army said it would not be funding any products from the effort. Sorta like UCAR.
 
You mean Transformer/T-X?
I hope it died a horrible death. If you read the requirements of the program, you see that the only possible outcome is a vehicle that is both a horrible car and a horrible airplane. Sorry for the bitterness, i spent a good chunk of time on that kluge.
 
AeroFranz said:
You mean Transformer/T-X?
I hope it died a horrible death. If you read the requirements of the program, you see that the only possible outcome is a vehicle that is both a horrible car and a horrible airplane. Sorry for the bitterness, i spent a good chunk of time on that kluge.
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I always wondered how such a bad idea survived as long as it did. Discounting the technical challenges, I always worried about trying to make a vehicle that required everyone to be able to fly a brick. Yeah I know it was suppose to have "push to fly" but what is a driver to do when the system decides to reboot mid-flight?
 
http://www.bbc.com/future/story/20130228-x-plane-plans-for-radical-takeoff
 
Grey Havoc said:
http://www.bbc.com/future/story/20130228-x-plane-plans-for-radical-takeoff
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That is a good article on the state of VTOL science and the perceptions of the world at large. I have to agree that I am not sure that something exceedingly different from previous ideas will come out of the air. I think there are a lot of the aircraft on the wheel that floundered due to availability of technology to overcome weight and power issues. I would bet that slowed rotor tilt rotor, folding tilt rotor, perhaps XV-5 fan in wing (if weight fraction and fuel consumption can be kept reasonable) are likely canidates. I argue this because the more you want something to act like a high speed airplane, the more you have to make it look and act like one. Of course you can use more power to push it through the air, but then you get into the evil space/weight/power conundrum that has caused the VTOL wheel to gather the “Wheel of Misfortune” moniker.
 
One can hope variable diameter rotors for tilt rotor aircraft might make an appearance this time around. Though odds are the disk rotor folks would have a flying prototype first.
 

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But in the moment I cannot remember another ducted fan design using fuselage mounted, fixed ducts plus swivelling
ones at the wing tips. Maybe the advantage is, that the tilting units don't need to be oversized, just for achieving VTO.
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...agree!

One of the challenges in making ducted fan viable for VTOL is to create a duct lip that is optimized for static thrust but has low drag in fast conventional flight. Creating a variable geometry one seems particularly complex (e.g. doak patent drawing). In case of the Phantom Swift the geometry of the fixed-fans could be optimized for static and the tilt-fans for dynamic thrust.
I wonder how the propulsion of a full scale model would look like...turbine-shaft driven, all electric, hybrid, ?

Btw, I've done some experimenting with a ducted propeller VTOL. Lots of fun ;D
 

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I wonder why American Dynamics combined a kind of stealthy fuselage with rotors on the outer wing.
 
Reaper said:
I wonder why American Dynamics combined a kind of stealthy fuselage with rotors on the outer wing.
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Looking at that model, I'm not sure, that it already has much stealth built into it. The fuselage has an ogival
cross section, because the fans have to fit into it, but that's not a very stealthy shape, I think. And the model
probably is just meant to prove that it is flyable.
 
Artist's impression of Sikorsky/Lockheed Martin Skunkworks VTOL X-Plane.

Source:
http://www.slashgear.com/darpa-x-plane-phase-1-contract-granted-to-sikorsky-13308744/


Sikorsky Press Release:
December 12, 2013

Source:
http://www.sikorsky.com/About+Sikorsky/News/Press+Details?pressvcmid=ae95c02e57be2410VgnVCM1000004f62529fRCRD


STRATFORD, Connecticut - Sikorsky Innovations, the technology development organization of Sikorsky Aircraft Corp., today announced it has won a contract for Phase 1 of the Vertical Take-Off and Landing Experimental Aircraft (VTOL X-Plane) program by the U.S. Defense Advanced Research Projects Agency (DARPA).


The proposed effort is valued at $15 million to develop the preliminary design for the VTOL X-Plane, a high-speed vertical takeoff-and-landing aircraft with the hover capability of a helicopter. Sikorsky Aircraft Corp. is a subsidiary of United Technologies Corp. (NYSE:UTX).

Sikorsky Innovations is teamed with Lockheed Martin’s Skunk Works® for the VTOL X-Plane development of its Unmanned Rotor Blown Wing concept. The Rotor Blown Wing represents a unique integration of fixed wing aerodynamics and advanced rotor control to provide a low complexity configuration capable of meeting the challenging DARPA program goals. The contract duration is 22 months. The program goal is to build and fly a demonstrator aircraft with first flight anticipated in the fourth quarter of 2017.

Sikorsky Innovations plans to lead the program from its Fort Worth office, leveraging talent from both Stratford, Connecticut, and West Palm Beach, Florida, engineering centers.

The overall VTOL X-Plane program is a 52-month, $130 million effort to fly an experimental aircraft capable of exceeding 300 kt., with a hover efficiency of 75 percent or better and a cruise lift-to-drag ratio of 10 or more. During Phase 1, Sikorsky Innovations and Lockheed Martin’s Skunk Works will conduct trade studies and develop the initial design.

“Sikorsky has a solid legacy of developing game-changing advances, and the DARPA X-Plane program is exactly the kind of project that Sikorsky Innovations was created to execute,” said Chris VanBuiten, Vice President of Sikorsky Innovations. “We are an agile, networked team dedicated to demonstrating innovative solutions to the toughest challenges in vertical flight. This program explores a generation of innovation that has yet to be introduced, and we have the opportunity to develop our novel design of the X-Plane concept with our partner at Skunk Works. It is an exciting project, and we are thrilled to be among the contract winners.”

Mark Miller, Sikorsky’s Vice President of Research & Engineering, added, “We anticipate that DARPA will release up to four Phase 1 awards, so this is a significant win for Sikorsky Innovations. We have a non-traditional technical solution, and this is an opportunity for Sikorsky Innovations to excel, to expand our relationship with DARPA, and to embark on a great partnering opportunity with another company known for its innovative solutions – Lockheed Martin’s Skunk Works.”

Sikorsky and Lockheed Martin have extensive experience working together during four decades developing, delivering and supporting 600 operational SH-60B and MH-60R/S maritime helicopters to the U.S. Navy. In addition, Sikorsky and Lockheed Martin have teamed up to offer Sikorsky’s proven S-92® helicopter in response to the U.S. Navy’s formal Request for Proposals to build the next Marine One helicopter fleet, as well as teaming for the U.S. Air Force Combat Rescue Helicopter.

Other leading edge programs under way at Sikorsky Innovations include the Sikorsky-Boeing X2® coaxial rigid rotor technology Defiant helicopter demonstrator for the U.S. Army’s Joint Multi-Role Helicopter requirement.

Sikorsky Aircraft Corp., based in Stratford, Conn., is a world leader in helicopter design, manufacture, and service. United Technologies Corp., based in Hartford, Conn., provides a broad range of high technology products and support services to the aerospace and building systems industries.
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Sikorsky's Rotor Blown Wing -- Look Familiar? by Graham Warwick

http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3ae8132818-653f-46d0-a42f-89c12f7f0ffb&plckScript=blogScript&plckElementId=blogDest

"the agency said it was looking for simplicity and elegance in design and encouraged innovative proposals and not simply improvements to existing designs."
:eek:
 
From the above article:
"DARPA is expected to award up to four Phase 1 contracts. Aurora Flight Sciences has one, but isn't saying what its design looks like."

Maybe like this ;)
 

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"Manassas, VA, February 4, 2014 - Aurora Flight Sciences announced today the award of a Phase I contract from the Defense Advanced Research Projects Agency (DARPA) Vertical Takeoff and Landing (VTOL) X-Plane program.
Aurora’s innovative VTOL X-Plane, known as LightningStrike, is designed for efficient hover and high speed, meeting DARPA’s ambitious goals for performance and useful load capacity..."
http://www.aurora.aero/Media/Press/Item.aspx?id=APR-312

...no pics of the LightningStrike so far :(

Btw, has the Excalibur UAV ever accomplished a successful transition to forward flight? http://www.secretprojects.co.uk/forum/index.php/topic,7280.msg62993.html#msg62993
 
I don't think they got that far before the funding ran out. No one was showing any real interest in the concept.
 
VTOLicious said:
Sikorsky's Rotor Blown Wing -- Look Familiar? by Graham Warwick

http://www.aviationweek.com/Blogs.aspx?plckBlogId=Blog:27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3ae8132818-653f-46d0-a42f-89c12f7f0ffb&plckScript=blogScript&plckElementId=blogDest

"the agency said it was looking for simplicity and elegance in design and encouraged innovative proposals and not simply improvements to existing designs."
:eek:
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what you :eek: said... speaking of driverless cars..
 

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Sorry to see that Bell did not give the stop-fold concept a shot.
 
The fourth concept from Aurora will not be shown until June at the earliest.


Yasotay, i too think that folding rotors looked promising. I believe the BAA strongly discouraged the development of new powerplants, or even substantial modifications. The FTR might have fallen under that category.
 
DARPA Tasks Industry to Design Speedy Hybrid Helo

Four companies will submit design proposals to build a high-speed experimental vertical takeoff and landing demonstrator for the Defense Advanced Research Projects Agency, DARPA announced. "The proposals we’ve chosen aim to create new technologies and incorporate existing ones that VTOL designs so far have not succeeded in developing," said DARPA Program Manager Ashish Bagai in a March 18 release. The agency selected Aurora Flight Sciences, Boeing, Karem Aircraft, and Sikorsky Aircraft to develop VTOL designs capable of a top speed between 300 knots and 400 knots, without sacrificing range and payload. Craft should be capable of carrying a payload of 40 percent of their gross weight, attain a hovering efficiency of 75 percent, and double the lift-to-drag ratio of current designs, according to the release. The agency plans to select a winning design in late 2015, which would be built and test-flown in the "2017-18 timeframe," according to DARPA. “For generations, new designs for vertical takeoff and landing aircraft have remained unable to increase top speed without sacrificing range, efficiency, or the ability to do useful work,” states the release. The VTOL Experimental Plane program “seeks to overcome these challenges through innovative cross-pollination between the fixed-wing and rotary-wing worlds . . .”
 
"DARPA to progress VTOL X-Plane as Boeing reveals Phantom Swift details"
Gareth Jennings, St Louis - IHS Jane's International Defence Review
25 June 2014

Source:
http://www.janes.com/article/39936/darpa-to-progress-vtol-x-plane-as-boeing-reveals-phantom-swift-details

The US Defense Advanced Research Projects Agency (DARPA) is to undertake conceptual design reviews for the four vertical take-off and landing (VTOL) X-Plane contenders in the coming weeks, a Boeing programme official disclosed on 24 June.

Speaking at the company's St Louis facility in Missouri, Brian Ritter, programme manager for Phantom Swift, said that initial reviews of the solutions being proposed by Aurora Flight Sciences, Boeing, Karem, and Sikorsky will be undertaken at the end of July. This will be followed with a preliminary design review by the end of 2015.

Announced by DARPA in early 2013, the VTOL X-Plane programme is geared at demonstrating efficient hover and high-speed flight. The specific requirements are that the aircraft achieve a top sustained flight speed of 300 kt to 400 kt; raise aircraft hover efficiency from 60% to at least 75%; present a more favourable cruise lift-to-drag ratio of at least 10, up from the current 5-6; and carry a useful load of at least 40% of the vehicle's projected gross weight of 10,000-12,000 lb (4,500-5,450 kg).

Of the four contenders, Boeing's Phantom Swift is currently the only one to have been built (as a 17% scale model) and flown. Speaking to reporters at St Louis, Ritter disclosed details of the Phantom Swift, which plans to achieve DARPAs goals through the use of ducted-fan technology.

"The combination of body-fans and tilt-wing fans for improved controllability is the unique feature of the Phantom Swift," Ritter said, adding: "In the challenge of efficient hover and high-speed flight the answer is in ducted-fan technology, and this is something that Boeing is now investing heavily in."

In its full-sized configuration the Phantom Swift will measure 15.2 m (50 ft) from wingtip to wingtip, 13.4 m (44 ft) from nose to tail, and weighs in at to 5,450 kg (12,000 lb). With two downward facing fans in the main body of the aircraft for vertical lift, payloads would be housed in bays in the nose, mid-section, and tail of the Phantom Swift.

While the demonstrator will be powered by a conventional General Electric CT7-8 engine, the long-term plan is to incorporate an all-electric drive as soon as the technology makes it feasible. In high-speed cruise the lift fans are shut down and doors are closed for greater aerodynamic performance (forward propulsion is provided by the wingtip thrusters).

While DARPA did not specify whether the aircraft be manned or unmanned, all of the entrants have opted for unmanned. However, Ritter said there is potential for the full-scale Phantom Swift to be manned, and that Boeing sees a whole family of platforms based on the aircraft.

With Phase 1 contracts for the USD130 million VTOL X-Plane programme awarded to the four competitors, Phase 2 and Phase 3 will see the entrants downselected to one platform with the goal of flight trials in the 2017-18 timeframe.
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Announced by DARPA in early 2013, the VTOL X-Plane programme is geared at demonstrating efficient hover and high-speed flight. The specific requirements are that the aircraft achieve a top sustained flight speed of 300 kt to 400 kt; raise aircraft hover efficiency from 60% to at least 75%; present a more favourable cruise lift-to-drag ratio of at least 10, up from the current 5-6; and carry a useful load of at least 40% of the vehicle's projected gross weight of 10,000-12,000 lb (4,500-5,450 kg).
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I was wondering how to determine hover efficiency in % ?

I know that a VTOL-aircraft with high power loading and low disc loading is the most efficient at hovering.
For comparison a typical 12000lb helo:

Bell 412EP
Rotor diameter: 46 ft (14.0 m)
Disc area: 1,662 ft² (154.4 m²)
Max. takeoff weight: 11,900 lb (5,397 kg)
Powerplant: 2× Pratt&Whitney Canada PT6T-3BE Twin-Pac turboshafts, 900 shp (671 kW) each

Power loading: 4 kg/kW (6.6 lb/shp)
Disc loading: 35 kg/m² (7.2 lb/ft²)

% hover efficiency?

BR Michael
 
Well Mike, ...?

I guess that is why it is DARPA hard.
 
As far as I'm aware, hover efficiency is a rotary wing term for static thrust efficiency where you're simply looking at the ratio of power in to thrust out when relative airspeed is zero.

Therefore, from the parameters you've provided VTOLicious, we can't calculate this efficiency without knowing the actual maximum thrust output of the propeller system, which will also vary due to atmospheric conditions, propeller RPM and propeller pitch.

For VTOL aircraft, an increase in hover efficiency from 60% to >75% will therefore mean developing a more efficient means of turning power into thrust in order to increase the aircraft's range and fuel efficiency.
 
Dragon029 said:
As far as I'm aware, hover efficiency is a rotary wing term for static thrust efficiency where you're simply looking at the ratio of power in to thrust out when relative airspeed is zero.
Therefore, from the parameters you've provided VTOLicious, we can't calculate this efficiency without knowing the actual maximum thrust output of the propeller system, which will also vary due to atmospheric conditions, propeller RPM and propeller pitch.
For VTOL aircraft, an increase in hover efficiency from 60% to >75% will therefore mean developing a more efficient means of turning power into thrust in order to increase the aircraft's range and fuel efficiency.
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Thx for your input Dragon.

Hmm, the total efficiency of a propulsion system can be calculated if the efficiency factors of each component is known. Please correct me if I'm wrong:

For example a simple electric propulsion system consisting of
1) battery (0.9)
2) speed controller (0.85)
3) motor (0.8)
4) propeller (0.75)
By multiplying the individual factors (0.9x0.85x0.8x0.75) we get the total efficiency.

In my example only 46% of the battery power drawn is converted into actual useful power! (my factors are guesstimated, but the result seems plausible)

In order to achieve an overall efficiency of 65%, each individual component must have an efficiency of 90%...quite a challenge ;)
 
The hover efficiency blurb is really about "Figure of merit" (FOM).
In Disc actuator theory, figure of merit is defined as the ratio of ideal power required to hover to the actual power you are providing.
I did a very quick search and it looks like page one of this document would give you a rough idea, but just google "disc actuator theory" and you should come up with a lot of interesting hits


http://www.aerostudents.com/files/aircraftPerformance2/helicopters.pdf


also page 4 here:


http://www.public.iastate.edu/~aero442/unit2.pdf


Typical helicopters have a FOM of anywhere between .65 and .85. The problem is that optimizing the rotor for hover will hurt forward flight, so, like just about everything else in aircraft design, it's a tradeoff. If your mission requires a lot of hovering, you might design for better FOM and take the hit in flight.


Anyway, if you know the vehicle's weight, local air density, rotor area, and the power required to hover, you can figure out the FOM. The power required includes all the transmission losses, so it's whatever is measured at the engine's shaft.
 

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