Eurocopter X3: The world's fastest copter

Interesting.

I assume they stabilize the craft by spinning one of the two smaller props slightly faster than the other, to serve as both forward thrust and the ordinary role of the tail prop on a helicopter.

spectator:

Interesting.

I assume they stabilize the craft by spinning one of the two smaller props slightly faster than the other, to serve as both forward thrust and the ordinary role of the tail prop on a helicopter.

article:

The system does not feature any extra stabilizing systems or ballast systems that are needed to keep the system running correctly. The system does not even rely on an autopilot system; it can be flown by a normal helicopter pilot.

Extra engine, means extra fuel usage?
I mean, i could put 5 engines in a bigger helichopper and i would be the fastest? really?

How about a more comparable unit like weight/speed or fuel/speed?

That thing looks bad ass. Not as bad ass as Airwolf but still...

The X2 demonstrator by Sikorsky actually holds the current speed record for a helicopter for sustaining 250KTS true airspeed.

130 to 140 knots is more like 80 to 90 mph not 160.

How do they compensate for loss of lift on the trailing rotor?

130 to 140 knots is more like 80 to 90 mph not 160.

Wrong.

130 to 140 knots is more like 80 to 90 mph not 160.

Wrong.

1 statute mile=5280ft; 1 nautical mile= 6000ft

How do they compensate for loss of lift on the trailing rotor?

Not really an issue. Helicopters can lift far more than their own weight to begin with.

Anyway, it also has fixed wings on the sides and tail, so the increased forward speed propbably provides additional lift through Bernoulli principle.

This actually seems like a ridiculously obvious design concept.

130 to 140 knots is more like 80 to 90 mph not 160.

Wrong.

1 statute mile=5280ft; 1 nautical mile= 6000ft

Even so, that's only an increase in distance by a factor of 1.14. 130 kn is 149 (statute) mph, which is 130 (nautical) mph, not 80.

Edit: and hell, I did that without even knowing that a knot is a nautical mile per hour in the first place.

How do they compensate for loss of lift on the trailing rotor?

Not really an issue. Helicopters can lift far more than their own weight to begin with.

Anyway, it also has fixed wings on the sides and tail, so the increased forward speed propbably provides additional lift through Bernoulli principle.

This actually seems like a ridiculously obvious design concept.

Not so simple. As forward speed increases, lift increases on the forward moving rotor and decreases on the backward moving rotor. There must be some compensation or else the craft will roll to port. However the article states there is no stabilizing system. Hence my question- how did they do that?

However the article states there is no stabilizing system. Hence my question- how did they do that?

No -extra- stabilizing systems. They can use whatever they already have on-board like changing the AoA of the rotor blade.

OK- good point, but all other helicopters can do that too and they all have a top speed limited by loss of lift on trailing rotor- so what makes this copter different?

Sikorsky X2 is faster. 250-260 knots, 287-300 mph.
http://www.youtub...78TmZahI

OK- good point, but all other helicopters can do that too and they all have a top speed limited by loss of lift on trailing rotor- so what makes this copter different?

Look carefully at the video, I answered both aspects of the question in my two previous posts.

They can compensate for the tendency to roll by throttling up or down one of the forward facing props. The regular navigation systems would be designed to do this automatically.

The Bernouli wings that the forward facing props are mounted on provide lift as well, and the tail wing provides stability.

The forward facing port propeller spins slighly fewer RPMs than the starboard prop. This will counter the torque of the main rotor in the same way the tail prop counters the torque in an ordinary helicopter.

Thus it's actually more efficient than a traditional helicopter, since the stabilizing prop is providing forward thrust as it's primary function, and stability by a down throttling.

Extra engine, means extra fuel usage?
I mean, i could put 5 engines in a bigger helichopper and i would be the fastest? really?

How about a more comparable unit like weight/speed or fuel/speed?

If you are designing a military aircraft or especially a rescue vehicle, you are usually more interested in speed and flexibility, rather than fuel efficiency.

Technically, if people were really interested maximizing fuel efficiency, everything would be designed to travel as slow as possible, but time is money too. Fuel efficiency is rarely the most important parameter for human concerns. If you're talking freight, then fuel efficiency is most important, but if you're talking medical rescue helicopter, speed and flexibility are everything.

"... they all have a top speed limited by loss of lift on trailing rotor- so what makes this copter different?"

IIRC, they intend to slow the main rotor and use the stub wings' lift. I don't think you've seen this craft's limit yet...

"... they all have a top speed limited by loss of lift on trailing rotor- so what makes this copter different?"

IIRC, they intend to slow the main rotor and use the stub wings' lift. I don't think you've seen this craft's limit yet...

That makes sense- and with five rotor blades they can afford to slow the rotation. After watching the video, also noticed control surfaces on the wings which could compensate for roll. Thanks

"... they all have a top speed limited by loss of lift on trailing rotor- so what makes this copter different?"

IIRC, they intend to slow the main rotor and use the stub wings' lift. I don't think you've seen this craft's limit yet...

That makes sense- and with five rotor blades they can afford to slow the rotation. After watching the video, also noticed control surfaces on the wings which could compensate for roll. Thanks

Yes,that's my take on it.If the rotor blades are feathered to zero pitch,then the stubby wings would supply the lift.

An even sexier concept is DARPA's retracting rotor aircraft:http://gizmodo.co...e-flight

An even sexier concept is DARPA's retracting rotor aircraft:http://gizmodo.co...e-flight

Cool!

An even sexier concept is DARPA's retracting rotor aircraft:http://gizmodo.co...e-flight

That's hilarious.

While I was going to get chicken, I was wondering, "Why not put turbo props on that helicopter instead of the rotors?"

Well, they thought of everything, it seems...

The X3 Eurocopter is badly designed.

There is no easy and safe means of deploying a rescue winch, because of the twin rotors outboard the center of the craft.

Also, there is no platform to mount external stores because the side mounted propellors are in the way. Therefore not much good for weapons, fuel or emergency relief delivery.

The ingress and egress from the craft is also dangerous, because of the spinning propellors nearby.

Furthermore, if one of the side engines fails then its likely to cause the helicopter to fail because of the thrust imbalance, unless a heavy interconnecting transmission is installed, a la V-22.

Overall, nice looker, but a dud.

Wrong, wrong, wrong.

180 knots is 207 mph, NOT 267 mph. This is a modest improvement, NOT almost twice as fast. Remedial math needed here.

Isn't helicopter top speed ultimately limited by the rotor blade tip speed reaching the speed of sound?

perhaps it would be better if the propellers were mounted at the tail sides, so you have the winching space or use the fixed wing for hardpoints?

I wonder how far the military version of the Carter copter is now? It's all gone hush-hush since they took over that project. With turbines mounted it'll probably exceed 500mph and yet take off and land like a helicopter [ or more correct, like a gyrocopter]. I hope the personal air vehicle gets into the market soon. You can check it out at http://www.carter...pts.html in case you weren't aware of it's existence.

This really isn't all that new. Auto-gyro's are essentially the same thing except that with this design the main rotor is powered.

This brings up an important point the writer fails to mention. Loss of power to the main rotor in this design does not necessarily mean head for the ground like a rock. With separate motor(s) to the props to provide forward thrust, this thing should auto-gyro and maintain lift for a landing like a STOL plane. This design should be a little safer than a regular helicopter in certain circumstances.

First: all helicopters are autogyros upon loss of engine power.
Now, aside from the abysmally poor math and lack of any kind helicopter history knowledge, there is one overarching question. Is faster a justifiable helicopter design goal? A tilt rotor, like the Osprey, has a high forward speed (305kn)with VTOL. Larger more powerful helicopters like the CH-53 with a 170kn forward speed make the X3's gains seem puny by comparison.
So what has been built here? To me it is like the world's fastest canoe, simple to do, just add a large motor. Would you use it? No, probably not, too many compromises.

"The X3 Eurocopter is badly designed."

X-3's a 'proof of concept', surely ??

Easy to have pusher props to free up the stub wings for hard-points, easy on a bigger version to have a drop-ramp tailgate well clear of whirling bits...

Wrong, wrong, wrong.

180 knots is 207 mph, NOT 267 mph. This is a modest improvement, NOT almost twice as fast. Remedial math needed here.

You've mis-read something. The article uses 232kts.

The Eurocopter X3 can reach a top speed somewhere in the neighborhood of 267 mph (430 km/hr or 232 kts) in stable and level flight. It is not quite twice as fast as the current copters, but it is an impressive speed boost.

Which based on the correct conversion factor of 1.15mph per kts, this is exactly right.

232kts * 1.15mph/kts = 266.8mph

First: all helicopters are autogyros upon loss of engine power.
Now, aside from the abysmally poor math and lack of any kind helicopter history knowledge, there is one overarching question. Is faster a justifiable helicopter design goal? A tilt rotor, like the Osprey, has a high forward speed (305kn)with VTOL. Larger more powerful helicopters like the CH-53 with a 170kn forward speed make the X3's gains seem puny by comparison.
So what has been built here? To me it is like the world's fastest canoe, simple to do, just add a large motor. Would you use it? No, probably not, too many compromises.

I don't think a copter without power is an autogyro.A copter feeds all it's propulsive power into the rotor,whereas an autogyro has an unpowered rotor and an engine to push/pull it through the air.If either machine loses power,they can auto-rotate to earth.

I was very disappointed to read such a poor and badly written article on this site.
The author seems to have just copied and pasted from the press release, not understanding how this copter works.

1) X3 designers didn't "add another engine". The twin engines are both connected, like most high performances copters, to the main rotor.
2) The side propellers do what the tail rotor do in "normal" copters, a torque force to balance the main rotor's drag.
Simply, one propeller pulls forward while the other one pushes backwards, in respect to the copter's speed.
3) The propellers are connected to the main engines by shafts, there is no need to throttle the propeller's speed. Like tail rotors, the pilot just have to change the propeller's pitch.
4) In a "normal" copter, the tail rotor energy is wasted, in this one the side propellers contribute to the forward speed.
More, there is no tail rotor drag or "side push" to overcome.
Anyway, not completely new! Seek Gyrodyne on wikipedia.

First: all helicopters are autogyros upon loss of engine power.

No, they aren't. A regular helicopter has no forward thrust when it loses power. It has to dive to maintain forward speed if it loses power because the rotor will immediately start to lose RPM. The rotor in auto-gyro spins only with forward speed. Lose forward speed and the rotor stops spinning. They have to dive to keep speed and apply maximum lift to the rotor just above the ground and hope that it will provide enough lift to lessen the crash.

This new design provides forward power even if the rotor loses power. This should provide it with some glide characteristics. Forward speed will spin the rotor, it will provide lift and the copter should be able to have the glide characteristics of something other than a rock, unlike all other helicopters.

Edit, my comments were assuming the article is correct and the copter has multiple engines, if it doesn't than it will still glide like a rock.

A regular helicopter has no forward thrust when it loses power. It has to dive to maintain forward speed if it loses power because the rotor will immediately start to lose RPM.

Autorotation is gliding flight in a helicopter. Rotor RPM is not solely dependent on engine power. Airspeed and rotor pitch play an important role. In an autorotation landing, forward and downward movement through the air can be traded for lift upon landing by increasing rotor pitch just before touchdown. Helicopters do not make great gliders, but it is not crashing by any means. (Anyone want to try engine out landings in an F-16? Good luck with that.) I cant think of any commercial or military helicopter that isn't multi-engined anymore anyway. What helicopter crews fear most is transmission failure, followed by loss of control input, neither of which would be improved by this design.

What helicopter crews fear most is transmission failure, followed by loss of control input, neither of which would be improved by this design.

It would if the props had their own motors as the article states.

I know what auto-rotation is and I didn't explain it carefully assuming anyone reading it would also know. What you said does not refute anything I said.