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Subject: Eurocopter wants Sikorsky's speed record...
doggtag    9/28/2010 8:40:45 AM
Sikorsky X2 compound helicopter ( http://en.wikipedia.org/wiki/Sikorsky_X2 ) Eurocopter X3 ( http://www.reuters.com/article/idUSTRE68Q3V820100927?type=technologyNews&feedType=nl ( Compound helicopters, for all their perceived advantages over ordinary rotary winged and fixed wing types, never did really take off, so to speak (mass production as common as other aviation designs), as their complexities and shortcomings were deemed too dis-advantageous to outweight the advantages. But with the V-22 Osprey's teething troubles finally (mostly?) behind us now and the aircraft having a fairly safe operational record so far (USMC), and with Sikorsky's X2 achieving (and surpassing, albeit in a shallow dive) its planned-for 250KTAS speed record, and now Eurocopter just not being content playing second-fiddle to the point it not only wants to 1-up Sikorsky in not just breaking the helicopter speed record, but also 1-upping Sikorsky in its designation (EC X-3 vs S' X-2), ...will we finally see a new dawn for the compound helicopter, now that technology has given us more opportunities to overcome many of the earlier disadvantages experienced in compound helicopter development? Granted, with the EC X-3's current configuration, those wing-mounted props greatly reduce any tactical utility of carrying any sort of rockets, missiles, or gun pods under wing (except extremely inboard, right next to the fuselage), whereas the X-2 design's aft prop config allows multiple options in wing/pylon design for carrying armament.... The EC design might appeal finally to that executive civilian sector who has been seen as a VTOL golden opportunity, as civilian aircraft aren't concerned with underwing storage.... Myself, after seeing the movie, I think something along the lines of Avatar's "helicopter", a dual counter-rotating semi-ducted-fan kinda thing ( http://www.bing.com/images/search?q=Avatar+helicopter&FORM=IGRE&qpvt=Avatar+helicopter# ) might not be really that far fetched, and seems like it could offer much more utility, provided suitable turboshaft designs are available (as seen in the movie, there's little in the design that hasn't at some point already been tried in prototype form in the helicopter world). Still, is higher speed rotor craft finally going to become a reality, or is it still going to be one more Aviation Promised Land pipe dream that, no matter how hard we try and the tech evolves to further refine the designs, we still just will not overcome all (or more than enough of) the inherent flaws that have to date limited compound helis to mostly the realm of science fiction writers? ( ...things like rotor flutter at higher speeds, etc....sorry, no turbo-boosted Blue Thunders or AirWolves...)
 
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neiyold    whats really important...   9/28/2010 10:20:05 AM
...is that performance aside, the X3 is about as ugly a duckling as there ever was!  And I am not so sure I would want ingress/egress that thing until the wing rotor were at 0 rpm. 
 
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AThousandYoung       9/28/2010 2:31:53 PM
So the Russians got the Comanche to work with their coaxial rotor technology did they?
 
The X3 looks like a "thalidomide baby" duck.
 
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gf0012-aust       9/28/2010 4:47:34 PM

huh?  it's a modern day gyrocopter using pull instead of push.

at least with push they could have had a chance at mounting weapons ....

 
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MK       9/28/2010 5:16:41 PM
That's a really ugly design. What ever it is supposed to become.
 
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doggtag       9/28/2010 5:59:35 PM

That's a really ugly design. What ever it is supposed to become.

Years ago, there used to be this big passenger monstrosity called the Fairey Rotodyne.
Think of this new X-3 as liitle more than a new-technology, short-bus version of the big Fairey.  http://www.strategypage.com/CuteSoft_Client/CuteEditor/Images/emsmilep.gif" alt="" />
 
As far as ugly ducklings, the VSTOL world is full of gawd-awful-looking vertical take off hybrids combining fixed and rotary wing bits into one airframe.
 
 
 
Not all programs were as successful as others....
 
 
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AThousandYoung       9/29/2010 2:27:14 AM
Gyrocopter rotors are unpowered.  Is that true of this one?
 
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gf0012-aust       9/29/2010 3:46:54 AM

Gyrocopter rotors are unpowered.  Is that true of this one?

incorrect.  the germans were building powered gyros in the 1930's.  some had separate pusher motors, others were driven by CV joints on a PTO point.

they even trialled them on subs for a while.




 
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gf0012-aust       9/29/2010 3:50:43 AM

Gyrocopter rotors are unpowered.  Is that true of this one?

further to this, one of the reasons why you take Wiki entries with a grain of salt is because they can be spectacularly wrong.

point of fact, a RAN helo pilot friend of mine has 2 x gyros.  powered at the hub and at the pusher end.  the rotors are crown and pinion driven



 
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doggtag       9/29/2010 8:55:41 AM

Gyrocopter rotors are unpowered.  Is that true of this one?


Technically they are powered: it's just that the power isn't directly channeled (via drive shaft, etc) into the lifting rotor,
but rather the propulsion.
The forward momentum of the vehicle causes the rotor in a gyrocopter to spin, thus creating lift.
That's why gyros are not true helos, as they technically must, even minimally, taxi/accelerate to a useful take off speed.
 
This EC X-3, its rotor is powered, with the props getting power, most likely, via driveshafts from the gearbox that the turbines are coupled into (I'm assuming there's more than one engine in it...).
 
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doggtag    Correction....   9/29/2010 9:02:38 AM
On closer inspection of the X-3,
it does clearly appear that there are smallish intakes under the wing props,
evidence that they most likely use small turboprops rather than being coupled via shafts to a common gearbox near the turbine(s) under the main rotor....
 
My bad.
 
But those intakes up top the fuselage do clearly indicate there is at least one engine (turbine more likely than piston-based) up there that powers the rotor. 
 
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