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JMR (Joint Multi-Role) & FVL (Future Vertical Lift) Programs

sferrin

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obviate the retreating blade stall phenomen.

Tomcatvip has mentioned twice and I have mentioned before as well so this will be the 6th n 7th time mentioned..thinkin Karem has never been given a chance.. Some cave dwellin.
You said, "The manufacturer has stated the design eliminates retreating blade slowing."

That's not what they do. The retreating blade is going to have reduced relative motion to the airflow as you speed up no matter what. What they're doing is eliminating its impact. The is what Sikorsky X-2 technology (and the previous XCH-59) does (by having a lifting blade on both sides combined with a rigid rotor). It's what the AH-56 did.
Are the Sikorsky blades completely "unloaded " in winged based flight? Where are large wings. Do they use no main rotor for completely horizontal flight?
Because you have an advancing blade on both sides at all times you still have lift on both sides. The rigid rotors reduce flapping of the retreating blade (which loses more lift the faster you go). Doesn't need a wing. Both Karem's design and the AH-56 have the wing to unload the rotor and eliminate roll-off in the direction of the retreating blade.
Point is the Raider doesn't completely unload..
Doesn't need to be. The advancing rotor blades accomplish the same thing as a wing.
 

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
 

jsport

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The Russians wanted the Kamov 50 to ironically be a air superiority helicopter only to discover that counter rotaters touch blades in high dynamic maneuver. So not only is there range killing drag but there is no air to air combat manuver in counter rotaters..
 

sferrin

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The Russians wanted the Kamov 50 to ironically be a air superiority helicopter only to discover that counter rotaters touch blades in high dynamic maneuver.
The difference between rigid rotors and conventional.
 

sferrin

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
 

jsport

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
 

sferrin

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
The US Army doesn't care. It's not like they never learned to autorotate.
 

jsport

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
The US Army doesn't care. It's not like they never learned to autorotate.
exactly the point they picked low-old underperfroming tech, less range, more complexity, more weight, less payload, less maneuver, less speed, likely an inability to carry the mission load w/ a deep mag DEW, operates at generally lower altit etc what else ? political picks for congr district jobs not close to innovation.. endangering troops sooner than can be imagined.

These helicopters are needing to carry more and more almost by the week. The added weight of these complex and old technologies almost guarntee picking the "mature tech" will get ya piece Sh-t around late 2030s.. and then it is too late to start again. the Army then f'd w. an albatross.
 
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jsport

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Could someone please explain autorotate/how effective counter rotaters are compared to single direction?
 

sferrin

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
The US Army doesn't care. It's not like they never learned to autorotate.
exactly the point they picked low-old underperfroming tech, less range, more complexity, more weight, less payload, less maneuver, less speed, likely an inability to carry the mission load w/ a deep mag DEW, operates at generally lower altit etc what else ? political picks for congr district jobs not close to innovation.. endangering troops sooner than can be imagined.
It's easy to imagine the guy who didn't get picked is some kind of magician.
 

_Del_

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
If the rotor is "complete"ly unloaded, then it is not "augmenting" lift...
 

jsport

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Fuselage is lifted by the wings exclusively according to write ups. Therefore no load. Blade is still spinning adding lift w/o the burden of fuselage weight. all at forward speed of course -at hover wings must tilt vertical as you know.
 

sferrin

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Fuselage is lifted by the wings exclusively according to write ups. Therefore no load. Blade is still spinning adding lift w/o the burden of fuselage weight. all at forward speed of course -at hover wings must tilt vertical as you know.
How does the rotor impart lift with no load?
 

djfawcett

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Fuselage is lifted by the wings exclusively according to write ups. Therefore no load. Blade is still spinning adding lift w/o the burden of fuselage weight. all at forward speed of course -at hover wings must tilt vertical as you know.
How does the rotor impart lift with no load?
It doesn't
 

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Speed And Size Drive Advanced Options For U.S. Army’s Armed Scout

Oct 18, 2019

Graham Warwick | Aviation Week & Space Technology

The U.S. Army faces an array of options for its Future Attack Reconnaissance Aircraft (FARA). To meet the demanding size and speed requirements, four of the contenders have each unveiled different rotorcraft configurations. The fifth, Boeing, is keeping its design under wraps.

The Army’s requirements for a maximum speed of at least 180 kt. in an armed scout rotorcraft that can fit within a 40 X 40-ft. “box,” enabling it to fly between buildings in urban combat, is pushing manufacturers beyond conventional helicopter configurations.

Externally, Bell’s 360 Invictus is the most conventional of the offerings revealed so far, with a single main rotor and ducted tail rotor. But the design is optimized for high speed, with a low-drag tandem-seat fuselage, a wing to offload the rotor and a supplemental power unit to augment the single 3,000-shp-class General Electric T901 turboshaft to help push the helicopter to its 185-kt. top speed.

- Karem offers high-speed, active-rotor compound
- Sikorsky proposes derivative of coaxial-rotor S-97

AVX Aircraft, teamed with L3Harris Technologies, is proposing its Coaxial Compound Helicopter. This has side-by-side seating, a wing to offload the coaxial rotor and dual ducted fans for speed and agility. Details of Boeing’s design are sensitive, and the company does not want to give its competitors an edge, but the Army is fully informed on its initial design work says Mark Cherry, Phantom Works president.

Sikorsky is emphasizing growth capability to stay ahead of evolving threats with its FARA offering, the Raider X. Based on the X2 coaxial rigid-rotor compound configuration, the aircraft is a development of the S-97 Raider prototype now in flight-testing. The Raider X is about 20% larger, with a 14,000-lb. gross weight, compared to 11,000 lb. for the S-97, and a 39-ft.-dia. rotor, compared to 34 ft. for the Raider.

The Raider X will surpass the FARA program’s threshold of 180 kt. Sikorsky is not saying how fast it will fly but notes the S-97 has reached 215 and 207 kt. in level flight. This exceeds the 205-kt. target in the Army’s initial capability requirements document, says Tim Malia, Sikorsky’s director of future vertical lift-light.

The Army subsequently reduced the threshold maximum speed to enable a wider competition for the FARA program. But Malia says the greater speed and payload capability of the X2 configuration compared to a conventional helicopter provides growth capacity. “We looked at a single main rotor helicopter for FARA, but it would be minimally compliant in the early 2020s.

We need to be able to stay ahead of the threat into the 2030s and 2040s,” he says.

“Single main rotor will not be able to keep up. It’s already tapped out meeting the minimal FARA requirements. It does not have the ability to grow capability over time,” says
Malia. “We didn’t want to pull out all the stops to be minimally compliant when we had X2 able to carry more payload and go faster.”

The Raider X has four-blade rotors and a pusher propulsor. The coaxial rotors generate lift only on the advancing sides, eliminating retreating-blade stall and enabling higher speed. At high speed, 90% of the engine power goes to the propulsor, says Bill Fell, senior experimental test pilot. The propulsor is declutched at low speed to reduce noise.

The Raider X closely resembles the S-97 prototype, with side-by-side seating. Compared with tandem seating, this improves crew coordination and situational awareness, says Malia. “And we can do it aerodynamically because of the robust performance inherent in X2. We are not trying to get out every last ounce of drag.”

Behind the cockpit is a large internal weapons bay. Internal carriage of missiles and unmanned aircraft—which the Army calls air-launched effects (ALE)—is a FARA requirement, but Malia says the cabin-like volume of Raider X’s bay provides growth space for future, larger systems. “The minimum threshold works now, but what if in 2030 there are new ALE that can be decisive but can’t be carried?” he asks.

The Raider X is powered by a single T901—which will be government-furnished equipment to all FARA bidders. “We do not have an additional engine to increase speed,” Malia says. “We use the power available and have a solid design built around it. The T901 provides speeds out of the chute in excess of requirements, and as it improves we can take direct benefit.”

Sikorsky is using the industry-funded S-97 prototype to reduce risk for its FARA bid, conducting flight tests to validate models and optimize the Raider X design. This includes flying new rotor blades designed to reduce drag and vibration. “We are getting exactly the results the models said,” says Malia.

With two rotor systems and a propulsor, Sikorsky is paying close attention to the Raider X’s cost. “We have done a complete affordability analysis and design to cost. We are extremely confident we will come in under the cost goal,” he says.

Several divisions of parent Lockheed Martin are part of Sikorsky’s FARA team, Malia says, including Aeronautics, Missiles and Fire Control, and Rotary and Mission Systems. Swift Engineering will build the airframe if Sikorsky wins one of two FARA competitive prototype contracts scheduled to be awarded in March 2020. The Army flyoff is planned for 2023, with the first unit to be equipped by 2028.

Teamed with Northrop Grumman and Raytheon, Karem Aircraft is proposing a winged compound helicopter with an actively controlled main rotor, the AR40. “The hallmark feature is it can fly fast,” says Thomas Berger, Karem’s FARA program manager. “We go past the threshold requirement by about 20% and do it without any additional auxiliary propulsion on a single T901.” This implies a speed of about 215 kt.

Founded by Predator designer Abe Karem, the company is better known for its development of the Optimum Speed Tilt Rotor (OSTR). But the Army’s requirement that FARA fit within a 40 X 40-ft. box ruled out a tiltrotor design. The designation AR40 stands for “40-ft. active rotor.”

The AR40 has a single main rotor, wing and a unique swiveling tail rotor, which provides anti-torque control at low speed but swivels aft to provide propulsion for higher forward speed. “This is the best design we know to attack the requirement. It has low drag and low vibration at high speed,” Berger says.

In a conventional rotor, a swashplate and pitch links mechanically transmit cyclic and collective blade-pitch command to the rotor head. In Karem’s active rotor, the blades are individually controlled by electric actuators in the hub. This allows blade pitch to be precisely controlled to maximize performance and minimize drag and vibration at high speed, says Berger.

Additionally, power for the full-authority individual blade control actuators is generated in the hub, says Berger, eliminating the need for slip rings to transfer electrical power to the rotating rotor. The rotor has three stiff, lightweight blades and a rigid, hingeless hub. The lack of a swashplate and pitch links results in a slim pylon between fuselage and rotor, reducing drag.

To achieve high speed, “we reduce drag significantly and unload the rotor to the wing,” says Berger. “The swiveling tail rotor means we do not have the edgewise drag of a tail rotor. We store all the ordnance inside, stow the gun and fair the targeting turret.” The AR40 has side-by-side seating. This improves crew coordination and provides additional room behind the cockpit for mission equipment or a cabin for personnel. “It’s space for free,” he says.

While no active rotor has progressed beyond the R&D stage yet, Karem is developing the component technology under the Army’s Joint Multi-Role Technology Demonstration (JMR TD) program. Under this program, the company will ground-test a 36-ft. variable-speed active rotor for its OSTR design for the Army’s planned Future Long-Range Assault Aircraft.

The OSTR uses the same active control, lightweight blade and rigid hub technology as the AR40. The JMR TD rotor “is under component test, with the integrated test next year,” says Berger. “It will directly help reduce risk for [the AR40’s] individual blade control, rigid hub, blades, etc.”

Karem has worked with the Army’s science and technology community for many years, first on Joint Heavy Lift and later on JMR TD, but the company is still a relative unknown, so it has teamed with heavyweight partners Northrop for airframe production and Raytheon for the open-architecture mission system.

“Karem is the driving pioneer of the rotor and drive system.

Northrop Grumman brings full OEM production and support capability,” Berger says. Northrop company Scaled Composites is also involved and will likely build the prototype if the AR40 wins one of the two competitive prototype contracts.

Northrop Grumman Mission Systems will provide the avionics and cockpit integration. Raytheon will perform mission-system integration using its experience with modular open-architecture systems. “We have teamed with big OEMs who have the ability to provide managed risk,” says Berger.

—With Lee Hudson in Washington
To achieve high speed, “we reduce drag significantly and unload the rotor to the wing,” says Berger.

For the millioneth time This is like autism class..
 

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Speed And Size Drive Advanced Options For U.S. Army’s Armed Scout

Oct 18, 2019

Graham Warwick | Aviation Week & Space Technology

The U.S. Army faces an array of options for its Future Attack Reconnaissance Aircraft (FARA). To meet the demanding size and speed requirements, four of the contenders have each unveiled different rotorcraft configurations. The fifth, Boeing, is keeping its design under wraps.

The Army’s requirements for a maximum speed of at least 180 kt. in an armed scout rotorcraft that can fit within a 40 X 40-ft. “box,” enabling it to fly between buildings in urban combat, is pushing manufacturers beyond conventional helicopter configurations.

Externally, Bell’s 360 Invictus is the most conventional of the offerings revealed so far, with a single main rotor and ducted tail rotor. But the design is optimized for high speed, with a low-drag tandem-seat fuselage, a wing to offload the rotor and a supplemental power unit to augment the single 3,000-shp-class General Electric T901 turboshaft to help push the helicopter to its 185-kt. top speed.

- Karem offers high-speed, active-rotor compound
- Sikorsky proposes derivative of coaxial-rotor S-97

AVX Aircraft, teamed with L3Harris Technologies, is proposing its Coaxial Compound Helicopter. This has side-by-side seating, a wing to offload the coaxial rotor and dual ducted fans for speed and agility. Details of Boeing’s design are sensitive, and the company does not want to give its competitors an edge, but the Army is fully informed on its initial design work says Mark Cherry, Phantom Works president.

Sikorsky is emphasizing growth capability to stay ahead of evolving threats with its FARA offering, the Raider X. Based on the X2 coaxial rigid-rotor compound configuration, the aircraft is a development of the S-97 Raider prototype now in flight-testing. The Raider X is about 20% larger, with a 14,000-lb. gross weight, compared to 11,000 lb. for the S-97, and a 39-ft.-dia. rotor, compared to 34 ft. for the Raider.

The Raider X will surpass the FARA program’s threshold of 180 kt. Sikorsky is not saying how fast it will fly but notes the S-97 has reached 215 and 207 kt. in level flight. This exceeds the 205-kt. target in the Army’s initial capability requirements document, says Tim Malia, Sikorsky’s director of future vertical lift-light.

The Army subsequently reduced the threshold maximum speed to enable a wider competition for the FARA program. But Malia says the greater speed and payload capability of the X2 configuration compared to a conventional helicopter provides growth capacity. “We looked at a single main rotor helicopter for FARA, but it would be minimally compliant in the early 2020s.

We need to be able to stay ahead of the threat into the 2030s and 2040s,” he says.

“Single main rotor will not be able to keep up. It’s already tapped out meeting the minimal FARA requirements. It does not have the ability to grow capability over time,” says
Malia. “We didn’t want to pull out all the stops to be minimally compliant when we had X2 able to carry more payload and go faster.”

The Raider X has four-blade rotors and a pusher propulsor. The coaxial rotors generate lift only on the advancing sides, eliminating retreating-blade stall and enabling higher speed. At high speed, 90% of the engine power goes to the propulsor, says Bill Fell, senior experimental test pilot. The propulsor is declutched at low speed to reduce noise.

The Raider X closely resembles the S-97 prototype, with side-by-side seating. Compared with tandem seating, this improves crew coordination and situational awareness, says Malia. “And we can do it aerodynamically because of the robust performance inherent in X2. We are not trying to get out every last ounce of drag.”

Behind the cockpit is a large internal weapons bay. Internal carriage of missiles and unmanned aircraft—which the Army calls air-launched effects (ALE)—is a FARA requirement, but Malia says the cabin-like volume of Raider X’s bay provides growth space for future, larger systems. “The minimum threshold works now, but what if in 2030 there are new ALE that can be decisive but can’t be carried?” he asks.

The Raider X is powered by a single T901—which will be government-furnished equipment to all FARA bidders. “We do not have an additional engine to increase speed,” Malia says. “We use the power available and have a solid design built around it. The T901 provides speeds out of the chute in excess of requirements, and as it improves we can take direct benefit.”

Sikorsky is using the industry-funded S-97 prototype to reduce risk for its FARA bid, conducting flight tests to validate models and optimize the Raider X design. This includes flying new rotor blades designed to reduce drag and vibration. “We are getting exactly the results the models said,” says Malia.

With two rotor systems and a propulsor, Sikorsky is paying close attention to the Raider X’s cost. “We have done a complete affordability analysis and design to cost. We are extremely confident we will come in under the cost goal,” he says.

Several divisions of parent Lockheed Martin are part of Sikorsky’s FARA team, Malia says, including Aeronautics, Missiles and Fire Control, and Rotary and Mission Systems. Swift Engineering will build the airframe if Sikorsky wins one of two FARA competitive prototype contracts scheduled to be awarded in March 2020. The Army flyoff is planned for 2023, with the first unit to be equipped by 2028.

Teamed with Northrop Grumman and Raytheon, Karem Aircraft is proposing a winged compound helicopter with an actively controlled main rotor, the AR40. “The hallmark feature is it can fly fast,” says Thomas Berger, Karem’s FARA program manager. “We go past the threshold requirement by about 20% and do it without any additional auxiliary propulsion on a single T901.” This implies a speed of about 215 kt.

Founded by Predator designer Abe Karem, the company is better known for its development of the Optimum Speed Tilt Rotor (OSTR). But the Army’s requirement that FARA fit within a 40 X 40-ft. box ruled out a tiltrotor design. The designation AR40 stands for “40-ft. active rotor.”

The AR40 has a single main rotor, wing and a unique swiveling tail rotor, which provides anti-torque control at low speed but swivels aft to provide propulsion for higher forward speed. “This is the best design we know to attack the requirement. It has low drag and low vibration at high speed,” Berger says.

In a conventional rotor, a swashplate and pitch links mechanically transmit cyclic and collective blade-pitch command to the rotor head. In Karem’s active rotor, the blades are individually controlled by electric actuators in the hub. This allows blade pitch to be precisely controlled to maximize performance and minimize drag and vibration at high speed, says Berger.

Additionally, power for the full-authority individual blade control actuators is generated in the hub, says Berger, eliminating the need for slip rings to transfer electrical power to the rotating rotor. The rotor has three stiff, lightweight blades and a rigid, hingeless hub. The lack of a swashplate and pitch links results in a slim pylon between fuselage and rotor, reducing drag.

To achieve high speed, “we reduce drag significantly and unload the rotor to the wing,” says Berger. “The swiveling tail rotor means we do not have the edgewise drag of a tail rotor. We store all the ordnance inside, stow the gun and fair the targeting turret.” The AR40 has side-by-side seating. This improves crew coordination and provides additional room behind the cockpit for mission equipment or a cabin for personnel. “It’s space for free,” he says.

While no active rotor has progressed beyond the R&D stage yet, Karem is developing the component technology under the Army’s Joint Multi-Role Technology Demonstration (JMR TD) program. Under this program, the company will ground-test a 36-ft. variable-speed active rotor for its OSTR design for the Army’s planned Future Long-Range Assault Aircraft.

The OSTR uses the same active control, lightweight blade and rigid hub technology as the AR40. The JMR TD rotor “is under component test, with the integrated test next year,” says Berger. “It will directly help reduce risk for [the AR40’s] individual blade control, rigid hub, blades, etc.”

Karem has worked with the Army’s science and technology community for many years, first on Joint Heavy Lift and later on JMR TD, but the company is still a relative unknown, so it has teamed with heavyweight partners Northrop for airframe production and Raytheon for the open-architecture mission system.

“Karem is the driving pioneer of the rotor and drive system.

Northrop Grumman brings full OEM production and support capability,” Berger says. Northrop company Scaled Composites is also involved and will likely build the prototype if the AR40 wins one of the two competitive prototype contracts.

Northrop Grumman Mission Systems will provide the avionics and cockpit integration. Raytheon will perform mission-system integration using its experience with modular open-architecture systems. “We have teamed with big OEMs who have the ability to provide managed risk,” says Berger.

—With Lee Hudson in Washington
To achieve high speed, “we reduce drag significantly and unload the rotor to the wing,” says Berger.

For the millioneth time This is like autism class..
Yes it is. But not for the reason you think so. "Unload" does not neccesarily mean "COMPLETELY unload". The Karem design might very well still have rotor load, just a significantly reduced one.
But a rotor cannot add lift if there is no load. That's the whole point.
 

sferrin

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jsport

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what part of "unload to the wing" One is either calling the developer a liar or not. People living in their own private Idaho.
 

sferrin

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what part of "unload to the wing" One is either calling the developer a liar or not. People living in their own private Idaho.
I'm not sure you understand what you're saying. The rotor is unloaded BECAUSE the wing is taking up the load. Imagine a weight hanging by a rope from a tree branch. In this example the tree branch is the rotor, the rope is the mast, and the weight is the aircraft. Now unload the rotor (tree branch) by lifting the weight with your hand (the wing). Now the tree branch is unloaded (because of your hand) and is contributing NOTHING to the position of the weight. The rotor is not, "Blade is still spinning adding lift w/o the burden of fuselage weight."
 

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
from previous
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
 

sferrin

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
from previous
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
"being augmented by a spinning rotor"

Except it's not. If it's completely unloaded (in the Z direction) all it is is a source of drag and weight. Nothing more.
 

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
from previous
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
"being augmented by a spinning rotor"

Except it's not. If it's completely unloaded (in the Z direction) all it is is a source of drag and weight. Nothing more.
cant speak for the contractor.. and not taking your word for it as advancing blade would seem to add lift as opposed to counter rotater which is always drag sticking way up. Thus the basis for original argument that counter rototars are step backward compared to Karem. Anytime one can fly as an airplane on a helicopter mission is a win..Only tiltrotors and Karem can. No others can.
 

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The whole point of the ABC is that the rotor itself functions as a pseudo-fixed wing in high speed forward flight. Only the forward moving blade on each rotor is producing lift and only lift (no thrust). So an ABC helicopter is basically "flying like an airplane on a helicopter mission". Note, conventional counter-rotating helicopters such as the Kamov Ka-52 do not function the same way, and they still require the rotors to provide propulsion..
 

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Flying as a pure aeroplane is superior to rotation based lift. Unloading eliminated all retreating stall better lift. No vibration.. Symetric lift phenomenon.
Except that Karem's isn't flying as a "pure airplane" hence the big whirly thingy on top.
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
from previous
Complete unload and eliminated retreating stall means they are flying a pure airplane+being augmented by a spinning rotor. Raider's asymetric lift from rototating rotors stops it drops like rock minus some autorotate.
"being augmented by a spinning rotor"

Except it's not. If it's completely unloaded (in the Z direction) all it is is a source of drag and weight. Nothing more.
cant speak for the contractor.. and not taking your word for it as advancing blade would seem to add lift as opposed to counter rotater which is always drag sticking way up. Thus the basis for original argument that counter rototars are step backward compared to Karem. Anytime one can fly as an airplane on a helicopter mission is a win..Only tiltrotors and Karem can. No others can.
You can't add lift AND be unloaded. They're literally the opposite.
 

jsport

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The whole point of the ABC is that the rotor itself functions as a pseudo-fixed wing in high speed forward flight. Only the forward moving blade on each rotor is producing lift and only lift (no thrust). So an ABC helicopter is basically "flying like an airplane on a helicopter mission". Note, conventional counter-rotating helicopters such as the Kamov Ka-52 do not function the same way, and they still require the rotors to provide propulsion..
Good information. However, ABC (a fan of) is (active propulsed wing) and still suffers from retreat stall/slow etc yes? So great, add the ABC but fly mostly on a (passive, non propulsed) wing at high speed.
Stacked rotors add rng killing drag, weight, complexity, maintainence, additional maintainence training etc.
Why would Karem bother if no advantage...
 
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Desertfox

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ABCs do not suffer from retreating blade stall as the retreating blade is unloaded and is not producing any lift.
 

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Thank you for the clarification..
All the passive wing is always affording lift until tilted horizontal in hover.
 

yasotay

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By this time next year we will be awash in the bizdev battle of the age for rotorcraft. Bell will claim less risk for FARA and Sikorsky will claim better solution for the future (already seeing both). For FLRAA Bell will claim less risk, Sikorsky will claim that the Army really should not move away from helicopters.
 

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I for one cannot wait for the FARA fly off to start, the whole process of selecting the next helicopter for the US Army will be interesting to watch, and to see who eventually wins.
 

MihoshiK

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By this time next year we will be awash in the bizdev battle of the age for rotorcraft. Bell will claim less risk for FARA and Sikorsky will claim better solution for the future (already seeing both). For FLRAA Bell will claim less risk, Sikorsky will claim that the Army really should not move away from helicopters.
I can't help but remember the Airbus tanker bid. It too delivered capabilities well beyond what the Airforce officially asked for, and it won the competition... Only for that to sink them later on.

If I were Sikorsky I'd be very leery of delivering too much above and beyond what is actually asked for. Bell certainly is, instead going with as-asked-for, with a side order of reliability and proven tech.
 

FighterJock

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Anyone know what happened to Boeing’s contender for FARA? Did it survive the down select?
 

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Anyone know what happened to Boeing’s contender for FARA? Did it survive the down select?
Nope. Just the Bell Invictus and the LM-Sikorsky Raider-X. So it seems like they picked one low-risk, threshold performance option and one high-risk, objective-performance option. If LM-Sikorsky can make X2 tech really work at an affordable price point, they clearly have the edge here, but Bell probably has cost and risk on their side.
 
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VTOLicious

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Anyone know what happened to Boeing’s contender for FARA? Did it survive the down select?
Nope. Just the Bell Invictus and the LM-Sikorsky Raider-X. So it seems like they picked one low-risk, threshold performance option and one high-risk, objective-performance option. If LM-Sikorsky can make X2 tech really work at an affordable price point, they clearly have the edge here, but Bell probably has cost and risk on their side.
I would claim the Army sorted out the high-risk proposals (e.g. AR40) and went on with the most promising medium- (RaiderX) and low-risk (Invictus) proposal.
 

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Regarding the "loaded/Unloaded" controversy up thread, rotor blades can adjust their relative alpha, known as pitch, and they can be feathered. That means their pitch can be set such that the net lift across the blade is zero. That's what is meant by unloading the rotor. Then the wings will produce all of the lift. However, there is still a load on the rotor system, since it is still in the air stream, and that's drag. Since there isn't lift being produced by the rotor at that point, the induced drag is gone, but parasite/form drag and interference drag are still there.

I realize some of you in that section understand that, I was just trying to strip it down to the basics. FARA away.
 

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jsport

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Regarding the "loaded/Unloaded" controversy up thread, rotor blades can adjust their relative alpha, known as pitch, and they can be feathered. That means their pitch can be set such that the net lift across the blade is zero. That's what is meant by unloading the rotor. Then the wings will produce all of the lift. However, there is still a load on the rotor system, since it is still in the air stream, and that's drag. Since there isn't lift being produced by the rotor at that point, the induced drag is gone, but parasite/form drag and interference drag are still there.

I realize some of you in that section understand that, I was just trying to strip it down to the basics. FARA away.
"Then the wings will produce all of the lift." Thank you, all that needs to be said. regardless of the small amounts of parasite drag the AR40 is flying like an airplane ,, that can hover as a helicopter...noone else is doing that. Superior flight concept for efficient expenditure of available carried energy particularly when considering the vastness of Eurasian AORs and the increasing payload weight demands on craft...simple physics..
These other helicopters are programmed obsolescence.
 
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Well, and fine, but the kerfuffle began because you insisted the rotor was "augmenting lift" and also "completely unloaded". That's like saying the lightbulb was augmenting lighting and not using electricity from the system. It doesn't work.

I'm not sure the math on drag for completely unloaded rotors would look great either, but it would definitely be less than "normal". I don't think the quote you provided shows the plan would be to "completely" unload it in any event, but we've pretty much had to continue beating the horse.
 
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