Eurocopter’s quest for speed

November 22, 2010 by Tim McAdams

In the 1980s, Bell and Boeing Helicopters began developing a twin-turbo shaft military tilt rotor aircraft called the V22 Osprey. Bell then teamed with AgustaWestland to develop a commercial version known as the BA609 and it achieved its first flight in March 2003. During this time the helicopter industry was excited about VTOL aircraft reaching higher speeds. However, Eurocopter was quiet about its plans only saying it had no plans to develop a tilt-rotor aircraft.

On September 6, Eurocopter began test flights of its high-speed, long-range hybrid helicopter concept, which combines vertical takeoff and landing capabilities with fast cruise speeds of more than 220 knots. Called the X3, it is equipped with two turbo shaft engines that power a five-blade main rotor system and two propellers installed on short-span fixed wings. The engines are RTM322s, which power the company’s NH90 military transport. The main rotor gear box is a derivative of the yet-to-be certified EC175 medium size twin helicopter with a modification of two output drives for the propellers.

In cruise flight the rotor pitch is reduced to provide minimal drag and the small wings provide lift. Thrust comes from the propellers. There is no tail rotor so yaw and anti-torque are controlled by a standard pedal configuration that varies the thrust on each propeller separately. The aircraft can be flown like a traditional helicopter until 80 knots, then the main rotor pitch is reduced as the propeller thrust is increased.

According to Eurocopter, the hybrid aircraft will cost about 25 percent more per hour to operate than a conventional helicopter. However, with the increased speed the company points out that when measured in a per passenger/mile basis the operating costs will drop 20 percent. The X3 is currently a technology demonstrator, but Eurocopter says the concepts could be ready for production models in less than a decade.

16 Responses to “Eurocopter’s quest for speed”

  1. Kris Sundberg Says:

    This seems to be a similar take on the concept:

    http://www.youtube.com/watch?v=eMoUvlYXBc0&playnext=1&list=PL9419B3CF96809F0F&index=66

  2. Alex Kovnat Says:

    We note that for the same reason any 200 knot fixed wing aircraft (i.e. Mooney’s sleek, fast piston single engine planes) has retractible landing gear, so does the Eurocopter rotorcraft shown above, as does the Sikorsky X-2.

    Since a sina qua non of military helicoptering is off-airport landings wherever you can find a large enough clearing, I would like to ask: Is it possible to design a retractible landing gear that can withstand whatever rigors current military helicopters have to withstand, yet fit within a reasonably sized cavity? With current rotary wing birds like the Black Hawk, this isn’t a problem because the landing gear is a fixed skid – no wheels, no retraction mechanism. But then, nobody expects the Black Hawk, CH-47, CH-53, etc to keep up with one of Mooney’s piston single retractibles.

    I emphasize military helicoptering because, what else are we going to use one of these sophisticated 220-250 knot compound helicopters for? Theoretically such a helicopter would offer advantages for business aviation in that if you take off from, and arrive at your destination without needing airports at both ends, you can save time. The problem is, where are you going to take off from and land at, if not an airport?

    A Sikorsky X-2 type rotorcraft could be useful for civilian medical helicopter operations. Here again, if you’re going to cruise at Mooney-like speeds, you can’t use a rugged skid like our current medical helicopters. So it will be necessary to provide a cavity to hold the gear while in flight and, the pilot will be more concerned about the terrain being landed on, than is currently the case.

    All in all, I look forward to hearing about further developments from Sikorsky, Eurocopter and the Piasecki research firm.

  3. pdxpilot Says:

    Exciting future – when does it stop being a helicopter and become a airplane with a main rotor?

    Good showing of helicopters at AOPA Summit earlier in Long Beach – R44, R66 from Robinson and LA Helicopters – Long Beach Police with their soon to be sold EC130 and Los Angeles Police with an AStar and CBP with another AStar!

  4. Jim Borger Says:

    Am I missing something? Alex Kovnat says Black Hawks have skids, not wheels? Is he saying the CH-47 and the CH-53 don’t have wheels? Maybe I’m just reading it wrong.

    As far as where they are going to land, other than at airports, how about 250 nm offshore? Right now it takes me 1 3/4 hours one way if I’m not pushing a headwind and the weather is VFR. IFR adds another hours flying time plus time on the deck to refuel half way out.

    By the way, Clint Eastwood has an STC for retractable skids, so yes they could design a landing gear to withstand military needs.

  5. Ehud Gavron Says:

    Clint Eastwood has no STC for retractable skids.

    While I love a good rumor — especially if it makes flying helicopters better — this is one that should be put to rest.

    I’m sure the thought is of the Bell 206 with retractable wheels. Bell offered. The market declined to accept. End of story.
    Here’s one source: http://www.pprune.org/rotorheads/425189-bell-206-retractable-gear-info-please.html

    E

  6. Jim Borger Says:

    I read about in Rotor & Wing, they must of had it wrong, many years ago but the idea of retractable skids on a 206 made no sense to me. The weifgt penalty alone makes them impractable.

  7. Rick Bruns Says:

    Alex Kovnat Says: “With current rotary wing birds like the Black Hawk, this isn’t a problem because the landing gear is a fixed skid – no wheels, no retraction mechanism.”
    Lost me there … after 4,500 + hrs in them, I’ve never noticed the “fixed skids” on a Blackhawk.
    Alex, please clarify your point!

  8. Chris Way Says:

    Here is a video of the X3:

    http://www.youtube.com/watch?v=LxhogYKwV7Y

  9. Capt JB Says:

    Guys,

    Speed limitation on helicopters is NOT due to landing gear , but to maximum speed a on blades. Remember the helicopter spin its blades to obtain lift, when the airplane is tracted by it propeller. Hence the zero airspeed stall existing for a helicopter (hovering).
    The speed affecting the blade is calculated by adding the airspeed to the blade proper speed for the advancing blade, and by subtracting airspeed from blade own speed for the retreating blade. This airspeed difference is also a lift generation difference, which is controlled by the flapping hinge of the blade.
    This flapping hinge has limitations like to not hit and chop the tailboom, ouppps.
    The fastest helicopter in the world is a lynx and has the advantage of having a rigid main rotor.
    At speed over 200kts the flapping hinges are starting to have difficulties to compensate difference of lift between advancing blade and retreating blade. This is why the idea of the X3 is to use propellers to move the helicopter and slowly reduce the main rotor speed – which lost of lift will be compensated by the small wings.
    Many solutions to obtain this have been studied, V-22, Fairey Rotoryne, etc. the X3 is based on the same principle the fairey rotodyne and should be more succesfull than the V-22 because it is not using tilt rotors but a single main rotor to provide lift at low airspeed, and will have a same aerodynamic reactions as a normal helicopter.

  10. Steve King Says:

    A comment on Nov 23: “Exciting future – when does it stop being a helicopter and become a airplane with a main rotor?”
    Seems to me that the X3 is somewhere between being a helicopter and a girocopter, and is closer to being a girocopter, like the 1930′s Pitcairn-Cierva Autogiros. http://en.wikipedia.org/wiki/Pitcairn_Autogiro_Company.

  11. Alex Kovnat Says:

    I took another look at various pictures I could find and yes, the Black Hawk numerous other helo designs do indeed have wheels. Sorry abt. that.

  12. Sean C Says:

    I understand that this is a prototype, but I hope for the passengers sake that they’re able to find a safer configuration prior to serial production. This is a huge step backwards for Eurocopter safety-wise, with all those unprotected blades whirling right where the passengers are going to load and unload.

  13. Alex Kovnat Says:

    Safety shouldn’t be a problem. The two side propellers, are no more (or less!) dangerous than the propellers on a King Air or any other airplane. Or for that matter, the tail rotor on a conventional helicopter.

  14. Jay B Says:

    These new variants still have the main limitation that all helicopters have, only more so, that being TOO MANY MOVING PARTS! It’s not natural like a nice fixed wing. Believe it.

  15. Nick Says:

    Flapping hinge is not the main limiter for high speed…blade tip compressibility effects for the advancing blade (supersonic) and retreating blade stall are a little bit more. Lynx used a very interesting blade tip shape to help this…remember that once getting too close to speed of sound it takes a LOT more power due to increased drag.

    Unless I have missed something, the military aircraft with OLEO struts can take a LOT more rate of decent than ANY skid, at least in normal landings (I dont typically crash land each different type I fly). I can tell you that a FIRM landing in an SH-60 on a ship would be a catastrophic airframe failure on a jet ranger!

  16. Nick Says:

    ohh yeah, and anyone else think that X-3 is a low blow considering Sikorsky X-2 was named (to the public at least) first!?!

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