Latest Trends in Helicopter Design

pmaitra

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Sikorsky finally went the Kamov way?

Promising 'new' technology.

Coaxial? Yes, already perfected by Kamov. However, the blades are fixed and do not twist, as in a typical helicopter to provide lateral motion. Rather, that is done by a third propeller. Benefit? Reduced noise!

 
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Ray

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Kamov Ka 50
 
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pmaitra

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Helicopter with wings promises to change aviation world

Helicopter with wings promises to change aviation world


By Jorn Madslien
Business reporter, BBC News, Marignane, France
15 June 2011 Last updated at 18:03 ET


Click to play


Eurocopter's Jean-Michel Billig: 'It's a game changer in the way we use helicopters in our day-to-day life"

Surging in from the west through one of Provence's many beautiful valleys, a peculiar-looking aircraft is preceded by an unfamiliar sound.

The deep chugging rumbling of a conventional helicopter rotor is mixed with the loud whining noise of two wing-mounted forward-facing propellers, making it difficult to guess what is coming.

As the aircraft swoops over Montagne Sainte-Victoire, shaking the windows in holiday cottages and farm houses below, it becomes clear that this flying machine resembles nothing else in the skies.

Eurocopter's X3 rotorcraft - pronounced "X cubed" - is basically a chopper with wings, which will be seen for the first time by the public next week as part of the aerial displays at the Paris air show.

The prototype combines the versatility of a helicopter, by way of vertical take-off and landing, with the higher speed of a plane.

"It's exactly like a helicopter," says flight test engineer Dominique Fournier. "But as soon as you've taken off, it's exactly like a fixed-wing aircraft."

Game changers


Helicraft such as the X3 are set to revolutionise aviation, company executives say

The X3 is one of the fastest rotorcraft in the world, having achieved a cruising speed of 232 knots (430 km/h or 267 mph) during a test flight on 18 May.

Though not quite as fast as US rival Sikorsky's equally futuristic-looking but differently designed X2, which achieved a true air speed of 250 knots last September, the X3 has nevertheless made the prospect of ultra-fast helicopters going on sale within years much more likely.

Consequently, both helicopter companies describe their innovations as "potential game changers".

"The aerospace industry today has a new horizon," according to Sikorsky's president Jeffrey Pino. Eurocopter's chief executive Lutz Bertling says "it will be a totally different way of flying".

Mission capability

"If you can do it with a balloon or a fixed wing or a bicycle, you don't buy an expensive helicopter"

Lutz Bertling
Chief executive, Eurocopter
For the pilot and for passengers, the difference lies in the "very different sensation from flying this when compared with an ordinary helicopter", according to experimental test pilot Herve Jammayroc. "In the X3 we accelerate and decelerate horizontally."

And although the X3 is perhaps a more complex machine to build, "it is easier to fly than a conventional helicopter", Mr Jammayroc says.

For Eurocopter's customers, it is all about balancing costs with how quickly and how far the aircraft can travel.

Hence, although the X3 is at least 50% faster than conventional helicopters, "the key message is not speed", according to chief executive Mr Bertling.

"The key message is productivity," he says, insisting that the X3's greater size makes it a more versatile rotorcraft than Sikorsky's X2.

"We are not selling helicopters, we are selling mission capability," Mr Bertling says.

"If you can do it with a balloon or a fixed wing or a bicycle, you don't buy an expensive helicopter."

Productive aircraft


Experimental test pilot Herve Jammayroc says it is easy to fly the X3

Eurocopter's aim is to deliver an aircraft that increases cruising speeds by 50%, while limiting any resulting increase in costs to 25%.

"The target is a productive aircraft," Mr Bertling says.

"So 210-220-230 knots for us is quite reasonable. And 270-280 knots may be conceivable, but fuel costs get too high."

With the X3, the required technology is pretty much there, according to Eurocopter's chief technology officer Jean-Michel Billig, who is in charge of research and development.

"Today, we believe it should cost in the region of 20% more than a similar size helicopter in terms of cost of ownership," he says.

Replacement programme


Fast helicraft such as the X3 are unlikely to replace conventional helicopters

The X3 forms part of a broader restructuring of Eurocopter, which includes plans to replace its entire current offering of six different helicopter models.

"We have a road map to renew our current product family over the next 10 years," says Mr Billig.

A helicopter programme costs about 1bn euros ($1.4bn; £876m) per year and typically lasts for about six years, so it is a costly exercise.

The company is also working on more fuel-efficient models, such as helicopters powered by diesel-electric hybrid engines, or unmanned or optionally manned helicopters, even full-sized ones that carry passengers.

Improving safety, both in terms of reliable systems and crew awareness, and to reduce operating and maintenance costs, are also central tasks.

Buoyant helicopter market


Profit margins are tight, both on the military and the civilian arena, chief executive Lutz Bertling says

Some replacement models might be similar to X3, says Mr Billig. "We are assessing the performance of X3 and we will apply it to helicopters where it makes sense," he says.

But his boss, Mr Bertling, adds there will still be a buoyant market for conventional helicopters. "For example, one of the great growth areas is servicing wind parks offshore, and here high speed doesn't make sense," he says.

Typically, the faster an aircraft moves horizontally, the less able it is at vertical take-offs and landings, so any aircraft that tries to be both helicopter and plane will be a compromise that is neither fish nor fowl in some situations.

Hence, rather than compete with fixed-wing planes or even with conventional helicopters, which will continue to serve growing markets in Asia, Latin America and the US, as well as here in Europe, the X3 and other helicraft of its ilk are carving out new niches in the aviation market.

Such aircraft could be used on new routes between city centres, such as between London and Brussels, or even within mega-cities, such as Mumbai, where vertical take-off and landing would save time by not having to travel to and from airports.

Other customers, such as the oil and gas industry, could speed up air shuttles to and from the rigs, thus enabling crews and experts to spend more time actually working.


Eurocopter is preparing to replace its entire helicopter model range

Such customers would be particularly sensitive to the cost of the helicraft, Mr Bertling observes.

Whereas for others, such as search-and-rescue or military customers, it is "less a question of money and more about mission success".

That does not make it a licence to print money, however.

"Operating with high margins in military areas - outside the US, I have to say - is not that easy in the current climate," Mr Bertling observes.

This year's Paris Air Show will take place at Le Bourget exhibition centre on the outskirts of Paris from 20 to 26 June 2011.

Source: BBC News - Helicopter with wings promises to change aviation world
 

pmaitra

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The X3 Concept

The X3 Concept

 
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pmaitra

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Reproduced from a different post by Sanjay:


Here is a video on an interesting approach to powered flight, called the Ornicopter:


Some of the more knowledgeable among you may know what an Ornithopter is - it's a machine that flaps its wings like a bird to achieve flight. An Ornicopter flaps its rotary wings/blades, causing them to travel in a rotary pattern like in a helicopter. Because the engine is not applying any torque, there is no counter-rotation problem, nor any tailboom-rotor required. A simpler piston-driven linear motor can be used, because it only needs to provide linear oscillation power to drive the flapping. This not only lowers the weight of the engine, but also improves engine reliability and ruggedness, reducing the likelihood of the engine seizing up or stalling.

Like a gyroplane, the ornicopter would also be more stable in turbulence or cross-winds. But most importantly, the ornicopter is more efficient than a helicopter in higher-altitude thinner air, where it is easier to flap. This is because there is a non-linear relationship between the work required to do the flapping, and the lift generated from the resulting vortices.

Why am I posting about it here? Well, I was thinking that the ornicopter might be useful for flying missions in the high Himalayas and Karakoram mountains, where India has its most militarized frontiers. If you see places like Siachen, these areas are particularly challenging for helicopters to fly in, because those conditions are at the limits of what the machines can perform.

I think that DRDO should try to develop systems which are specific to the challenges of India's particular defense environment. The technology of the ornicopter is definitely worth looking into for further research and development.
 
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pmaitra

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DARPA/Boeing DiscRotor

DARPA/Boeing DiscRotor

 
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pmaitra

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Kamov Ka 50
Reproduced from other posts by Bhramos:

Sikorsky reports that its X2 advancing blade concept technology demonstrator has achieved 168kt (311km/h) forward speed, putting the dual counter-rotating pusher-prop compound beyond the typical maximum speed for traditional helicopters and outside the reach of the company's S-76 chase vehicle's 155kt capability.

A follow-on flight, expected the week of 24 May, is to see X2 test pilot Kevin Bredenbeck accelerate the LHTEC T800-powered fly-by-wire pusher to 180kt, completing the third of four planned envelope expansion test phases. Phase four, which could begin as soon as mid-June, includes the first attempts to slow the X2's main rotors while opening the speed envelope to 250kt or more.

The prototype is designed with no clutch between the main rotors and propulsor, which requires the pilot to increase forward speed through the variable pitch control on the six-bladed rear propeller. Once in the 180kt realm, the X2's computer will automatically slow the main rotors and increase collective pitch to prevent tip speeds from entering high-drag transonic region, with Bredenbeck correspondingly increasing propulsor pitch to increase the X2's speed as the propulsor also slows.


© Ahsish Bagai/Sikorsky


Recent progress includes flights with the main landing gear retracted and two of the three main rotor fairings attached, tests of the main rotor active vibration system and 20-30kt of sideways flight in winds as high as 17-20kt. "We have quite a bit more control power left in this rotor for side flight," says Steve Weiner, chief engineer for the X2 programme.

Jim Kagdis, Sikorsky's manager of advanced programmes, says the flight-test team will "try to go as fast as we can" before installing the centre rotor fairing to determine the effect of the device on drag.

Kagdis expects that when the centre fairing is combined with the two elliptical main rotor fairings, already installed, the X2 will see a hub drag reduction of 40-45% compared with no fairing.

Vibration effects, which were problematic on Sikorsky's previous XH-59A demonstrator in the 1970s, have been "extremely low" so far, even without the active damping system turned on.

"We're really waiting to see what we get when go faster," says Weiner, adding that tests to date indicate that the X2 will meet its vibration targets - about the level of a traditional helicopter flying at 140kt - when cruising at its top speed of 250kt with the active system engaged.

Weiner says the only aerodynamic change to the structure made during the first three phases of the programme was the addition of 0.28m² (3ft²) of area to each of the outboard vertical end plates for yaw stability.

Weiner credits configuration maturity to Sikorsky's advanced analytical tools given that the company did not perform windtunnel tests of the design before flight-testing. He says windtunnel tests would likely precede the design for a production model, the first of which could be a systems development and demonstration vehicle for the US Army's potential competition to replace the Bell OH-58D Kiowa Warrior later this decade.

Sikorsky plans to begin using a 250kt Cessna Conquest twin turboprop for chase aircraft operations on the next flight.

Links posted in this story: Cessna|Cessna Conquest
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Sikorsky X2 breaks helicopter speed barrier


A Close Look At Sikorsky's Exotic X2!

 
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pmaitra

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Verticopter Tutorial

Verticopter Tutorial [parts 1,2/2]



Guys, download and post feedback please.
 
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