Eurocopter X3 hybrid

[keesje]

Flettner

Yes it the bad guys were a big step ahead aerospace innovation. Always (still) an issue in public communication.

On the X3 I saw it at the Paris Airshow this week. The program is winding down. Only 10 flight hours left. Eurocopter kept un usually secret on the X3 project before roll out. Apparently they modified the main rotor for better aerodynamics recently.



It's not like Eurocopter is now sitting on their hands as the article suggests. Contrary. Again in unusual secrecy Eurocopter is working on no less then 4 new generation platforms and they are not far away. Also a medium helicopter for which the X3 seems to have been the technology development platform..

X4 - 4-5t helicopter, first flight 2015
X6 - 11 t helicopter, first flight 2017
X9 - light twin, first flight 2019
X? - medium helicopter using X3 technology (militairy?) first flight 2017-2020

All will be significantly quieter, faster and fully fly by wire.

[Tickle]

Every time I see the X3 I think about all those big moving parts so close together.

I imagine they would have looked at ducted fans or small turbofans like in small business jets. I know they've all been done before on experimental aircraft.

Do you think ducted fans would have useful to focus the thrust and increase safety, if they weren't in the way of the main rotor's effect? Would they generate a coanda effect also?

(I am not too knowledgeable on this stuff.)

[Dave_Jackson]

Tickle,

This shows performance range of different propulsors. It appears that free props are the most efficient.

Dave

[riff_raff]

Tickle- Here's a 2010 US patent application from EC that shows one approach they considered for the pusher prop location on their X3.

[Tickle]

Thanks, Dave. I am sure I've seen you post that before. A very interesting comparison. I can see that ducts are definitely out then.

And thanks, Riff. That early design looks like something out of the old US military test machines, like a Cheyenne.

[chopper2004]

On this day a decade ago

On this day ten years ago the X3 flew for the first time ...I was lucky to see it fly to the theme tune of Airwolf a year later at Le Bourget. Then saw it again at Le Bourget in 2013 before being retired to the Museum there so (my photos below again).

cheers

[Agile]

looking back, quite a bit of modification on the EC365 airframe (or EC155 airframe)

• chopped out the fenestron
• Made the rotor mast much longer
• flying saucer rotor head

must have been a fun project to work on back then

[chopper2004]

a decade has passed

You Tube

cheers

[helispotter]

Originally Posted by chopper2004

a decade has passed...

cheers

It is a great compilation of video footage of the X3.

A few weeks ago, I had been reading about X3 on Wikipedia ( https://en.wikipedia.org/wiki/Eurocopter_X%C2%B3 ) prompted by another PPRuNe thread and they write: "...the X³ achieved 255 knots (472 km/h; 293 mph) in level flight on 7 June 2013, setting an unofficial helicopter speed record...". If indeed that speed remains unofficial, I have to ask why wouldn't Eurocopter (as it was still called at the time) have made an effort to have that speed ratified by the FAI (https://www.fai.org/records)?

As for FAI speed records for rotorcraft, I am not sure I have worked out how to use their website properly. When searching for "rotorcraft" speed records (limiting search to over 3km course or over a closed circuit), the highest speeds I could find were:

Closed course: 345.74 km/h (186.68 knots) - Thomas F. Doyle jr, USA - set in USA on 8 Feb 1982 in a Sikorsky S-76A
3km course: 372 km/h (200.86 knots) - Guy Dabadie - set in France on 19 Nov 1991 in an Aérospatiale AS 365 N

Perhaps compound helicopters are not categorised as "rotorcraft" by FAI ?

Update:

I should have looked at the link provided in the Wikipedia X3 article: https://en.wikipedia.org/wiki/Flight..._speed_records

It lists various additional speed records for what I consider to be rotorcraft, but many of those must be unofficial or at least not recognised by FAI: Westland Lynx, Eurocopter X3, Sikorsky X2, Bell-Boeing V-22, Bell 533.

[dangermouse]

There is only 1 official world speed record...

For a helicopter (which X3 wasn't), and we all know what that is....

400 kmh in a Lynx in level flight in August 1986...all the other claims are PR spin from Sikorsky or Airbus for compound aircraft.

DM

[Commando Cody]

Originally Posted by helispotter

It is a great compilation of video footage of the X3.

A few weeks ago, I had been reading about X3 on Wikipedia ( https://en.wikipedia.org/wiki/Eurocopter_X%C2%B3 ) prompted by another PPRuNe thread and they write: "...the X³ achieved 255 knots (472 km/h; 293 mph) in level flight on 7 June 2013, setting an unofficial helicopter speed record...". If indeed that speed remains unofficial, I have to ask why wouldn't Eurocopter (as it was still called at the time) have made an effort to have that speed ratified by the FAI (https://www.fai.org/records)?

As for FAI speed records for rotorcraft, I am not sure I have worked out how to use their website properly. When searching for "rotorcraft" speed records (limiting search to over 3km course or over a closed circuit), the highest speeds I could find were:

Closed course: 345.74 km/h (186.68 knots) - Thomas F. Doyle jr, USA - set in USA on 8 Feb 1982 in a Sikorsky S-76A
3km course: 372 km/h (200.86 knots) - Guy Dabadie - set in France on 19 Nov 1991 in an Aérospatiale AS 365 N

Perhaps compound helicopters are not categorised as "rotorcraft" by FAI ?

Update:

I should have looked at the link provided in the Wikipedia X3 article: https://en.wikipedia.org/wiki/Flight..._speed_records

It lists various additional speed records for what I consider to be rotorcraft, but many of those must be unofficial or at least not recognised by FAI: Westland Lynx, Eurocopter X3, Sikorsky X2, Bell-Boeing V-22, Bell 533.

The FAI defines a helicopter as a craft that derives all lift from rotors and all forward thrust from the same system that powers the rotors. If it has wings or auxiliary thrusters, it doesn't qualify. X3, V-22 and Bell 533 do not qualify. X2, OTOH, does qualify. In fact, after it hit 250 knots, the FAI invited Sikorsky to fly the standard closed course demonstration to take the world helicopter speed record. Sikorsky declined.

As far as the Westland Lynx goes, as Dangermouse said, it has held the FAI world helicopter speed record since 1986. And it didn't even have a pusher prop!

[helispotter]

Originally Posted by Commando Cody

The FAI defines a helicopter as a craft that derives all lift from rotors and all forward thrust from the same system that powers the rotors. If it has wings or auxiliary thrusters, it doesn't qualify. X3, V-22 and Bell 533 do not qualify. X2, OTOH, does qualify. In fact, after it hit 250 knots, the FAI invited Sikorsky to fly the standard closed course demonstration to take the world helicopter speed record. Sikorsky declined.

As far as the Westland Lynx goes, as Dangermouse said, it has held the FAI world helicopter speed record since 1986. And it didn't even have a pusher prop!

OK, Dangermouse and Commando Cody, while I would still call X3, V-22 and Bell 533 "rotorcraft" (the term FAI is using) I agree none are pure helicopters. Still, you would hope they then fall into another FAI class of aircraft that is capable of vertical takeoff such that they can also achieve official records in such a class, should the companies have sought an official record.

I have now found the Lynx speed record on FAI website. It is in the record category of "speed over a straight 15/25 km course", that being 400.87 km/h (216.45 knots): https://www.fai.org/record/1843

They also have an article about this record where they describe it as the "FAI Absolute Record for Speed for helicopters over a straight 15 and 25 km course": https://www.fai.org/news/11-august-1...revor-egginton

But hopefully someone can now explain to me why achieving that record didn't automatically also qualify it for the "Speed over a 3 km course" record for which the fastest "rotorcraft" is listed as the AS 365 N mentioned in my earlier post at 'a mere' 372 km/h (200.86 knots). It isn't possible to average 400.87 km/h over 15+ km straight course without at the same time averaging this (or higher) for at least one 3km segment of that run. It isn't obvious the "Speed over a 3km course" needs to be in a closed circuit as some other FAI records clearly are.

Update: The FAI has an item on the AS 365 N (AS 365 X) speed record here: https://www.fai.org/news/still-unbea...e-speed-record

It mentions: “The speed record over 3km requires the validation on four return journeys at an altitude of 300 feet or under throughout the journey and axis held at +/- 0.1N". So that would explain why the Lynx didn't automatically also gain this record. With return journeys, it isn't possible to take advantage of a tail wind. In any case the article implies this record needs to be conducted in winds below 5 knots. I am not sure what the "+/- 0.1N" is about though?

[Lonewolf_50]

First production unit of the X3 is expected ... when?
I may have mentioned this before, but where the propellers are and where the passenger doors are strike me as ground accidents waiting to happen.

[skadi]

Originally Posted by Lonewolf_50

First production unit of the X3 is expected ... when?
I may have mentioned this before, but where the propellers are and where the passenger doors are strike me as ground accidents waiting to happen.

X3 was just a demonstrator, next is the "Racer".

Airbus Racer

skadi

[Lonewolf_50]

Originally Posted by skadi

X3 was just a demonstrator, next is the "Racer".

Airbus Racer

Thanks for that. I like how the pusher props remove my ground safety concern somewhat.
I am guessing that yaw control in a hover will be differential thrust from the two pusher props.
Assuming FBW?
I expect that they'll have some fun tuning out the vibrations from the engine mounti / wing structures. All in a day's work, I suppose.
Any idea on first delivery?

[skadi]

Originally Posted by Lonewolf_50

Any idea on first delivery?

Its also just a demonstrator. First flight later this year.

skadi

[Commando Cody]

Originally Posted by helispotter

OK, Dangermouse and Commando Cody, while I would still call X3, V-22 and Bell 533 "rotorcraft" (the term FAI is using) I agree none are pure helicopters. Still, you would hope they then fall into another FAI class of aircraft that is capable of vertical takeoff such that they can also achieve official records in such a class, should the companies have sought an official record.

I have now found the Lynx speed record on FAI website. It is in the record category of "speed over a straight 15/25 km course", that being 400.87 km/h (216.45 knots): https://www.fai.org/record/1843

They also have an article about this record where they describe it as the "FAI Absolute Record for Speed for helicopters over a straight 15 and 25 km course": https://www.fai.org/news/11-august-1...revor-egginton

But hopefully someone can now explain to me why achieving that record didn't automatically also qualify it for the "Speed over a 3 km course" record for which the fastest "rotorcraft" is listed as the AS 365 N mentioned in my earlier post at 'a mere' 372 km/h (200.86 knots). It isn't possible to average 400.87 km/h over 15+ km straight course without at the same time averaging this (or higher) for at least one 3km segment of that run. It isn't obvious the "Speed over a 3km course" needs to be in a closed circuit as some other FAI records clearly are.

Update: The FAI has an item on the AS 365 N (AS 365 X) speed record here: https://www.fai.org/news/still-unbea...e-speed-record

It mentions: “The speed record over 3km requires the validation on four return journeys at an altitude of 300 feet or under throughout the journey and axis held at +/- 0.1N". So that would explain why the Lynx didn't automatically also gain this record. With return journeys, it isn't possible to take advantage of a tail wind. In any case the article implies this record needs to be conducted in winds below 5 knots. I am not sure what the "+/- 0.1N" is about though?

The key is that helicopters are a subset of rotorcraft. If they allowed a wing,said airfoil could be used to offload some of the lift from the rotors, thereby allowing the rotor to be slowed allowing for somewhat higher speed but t that point you're no longer fully rotorborne and that gives an artificial advantage over a pure helicopter. Similarly, if they allowed auxiliary propulsion you could hang just about anything on the side and with enough thrust blast your way to victory. Doing that, though, proves nothing. You could do it to any vehicle.

That's why they don't treat Til-Rotors as helicopters, but if Sikorsky would cooperate, any of their X2s could theoretically take the record, unless there's some other issue with the technology that keeps them from trying for it.

[megan]

If they allowed a wing,said airfoil could be used to offload some of the lift from the rotors, thereby allowing the rotor to be slowed allowing for somewhat higher speed but t that point you're no longer fully rotorborne and that gives an artificial advantage over a pure helicopter

So I guess the Cobra is not a pure helicopter as it has a wing Wonder what lift it does contribute.

[Commando Cody]

Originally Posted by megan

So I guess the Cobra is not a pure helicopter as it has a wing Wonder what lift it does contribute.

Remember we're talking the FAI's definition for the purposes of being eligible for the official speed record. As far as the wing on the Cobra goes, its primary purpose is to have some place to hang the weapons, not to offload the rotor to allow it to be slowed (the technology didn't even exist then) for higher speed. It does provide some lift that helps in toting the weapons in forward flight, but its main purpose is to provide weapons stations. Now the purpose of the wing on Invictus is to offload the rotor to allow it to be slowed for higher speeds. If the wing is detached, even though the drag is less, top speed is reduced. There is provision for one weapon station under each wing, but that's just a convenience. The 360 meets Army's requirement with internal stowage and carrying extra weapons under the wing means that weight has to be reduced somewhere else (probably fuel load) and drag goes up limiting top speed.

[helispotter]

As I was curious to see where compound rotorcraft, tiltrotors, etc fit into the FAI records, I searched for the relevant "rules" for rotorcraft. They can be found here:

https://www.fai.org/sites/default/fi...ended_2020.pdf

Sub-Class E-1 relates to "Helicopters" where mostly vertically oriented rotors substantially provide both lift and thrust (per comments by Commando Cody in post #131). But there are also sub classes E-2 (Tiltrotor), E-3 (Autogyro), M-1 (Compound), M-2 (Tiltwing / Tilt Engine). I couldn't find any M-1 or M-2 option in the pull-down menu for FAI records, so perhaps none have been (officially) set in those Sub-Classes to date? But there were a pair of old "E-2" speed records:

356.3 km/h (192.38 knots) speed over a straight 15-25km course set on 7 Oct 1961 in a Kamov Ka-22 Vintokryl.
307.22 km/h (165.88 knots) speed over a 100km closed circuit course with no payload set on 5 Jan 1959 in the Fairey XE 521 (Rotodyne).

I am not sure why either of these are classed as "Tiltrotors", but perhaps when these records were set, E-2 was defined quite differently in the code?

The code also defines how the speed records must be set. The record for speed over a 3km straight course must be achieved at a height (above ground) no greater than 150m and requires two pairs of flights in opposing directions with the speeds then averaged between the four runs. The speed over a 15/25 km straight course requires a pair of flights in opposite directions over a distance between 15 to 25 km. In this case altitude is unlimited but shouldn't be below 150m.