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Bloviating Zeppelin: Sikorsky X2: World's Fastest Helo?

Bloviating Zeppelin

(in-ep-toc'-ra-cy) - a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

Sunday, January 16, 2011

Sikorsky X2: World's Fastest Helo?

The Sikorsky X2 reached 262 knots in the above video, breaking the 250-knot barrier. This translates to 301.504 mph and 287.695 mph respectively.

Below, at the Heli Expo show in Anaheim, California on February 23rd, 2009, a Sikorsky chief test pilot explains the various system of the X2:

Cruises at 250 knots, with "dash" speeds of 270 knots (310.710 mph). All done with composite materials and a "fly by wire" system.

At this point the X2 is a test bed for potential future production.

But the story doesn't stop at the X2. Going back, the Lockheed XH-51A claimed an achieved speed of 263 knots (302.6 mph, 486.9 km/h) on November 29th of 1967.[4] This was accomplished with 16-foot wings and 2,500-hp turbojet engine attached to the left wing. The A was another test bed and never went into production.

Finally, the Bell 533 reached a top speed of 274.6 knots (316.0 mph, 508.6 km/h) in 1969, but it too was a one-off research test bed as well. The 533 likewise carried huge turbojet engines; this time two of them.

Technology marches on.


Thanks, Chris!


Blogger Well Seasoned Fool said...

Speed is almost always a good thing but Gross Weight Altitude, hover out of ground effect, is probably more usefull.

Sun Jan 16, 01:11:00 PM PST  
Blogger Bloviating Zeppelin said...

WSF: I would agree; and, of course, durability, dependability, cost of maintenance and a host of other factors. But isn't it interesting to see what you can do when you put a huge engine on something like they did in the 60s?

I can remember my father's comment, years ago, about the F-4 Phantom he flew one time: it merely proves that if you attach a large-enough engine, you can make a brick fly.


Sun Jan 16, 03:31:00 PM PST  
Blogger Greybeard said...

It's not a helicopter BZ.
It's a "compound".
It has a fixed wing to provide lift so the angle of attack on the rotors can be reduced. It also has a pusher propeller to provide thrust since the rotors, with their lowered A.O.A., cannot provide that thrust. Physics do provide an actual "barrier" to true helicopters, either through a phenomenon called "retreating blade stall" or due to the effects of compressibility on the advancing rotor as it approaches the shock wave of the speed of sound. In order for a rotorcraft to achieve speeds faster than 250 kts you have to resort to some pretty complex, un-helicopter technology.

The end game is to be able to provide fast, door-to-door service in certain venues. I used to make a 110 mile hospital-to-hospital flight in a relatively fast helicopter that took an hour in a no-wind condition. If I could take off in helicopter mode, then find a way to go 350 mph, then convert and land in helicopter mode at the receiving hospital, that flight might take 20 minutes.
Lifesaver. (But expensive.)

The technology is almost there. But can we afford it?

Sun Jan 16, 03:35:00 PM PST  
Blogger Greybeard said...

Okay, I was mistaken...
I was goin' on memory of an article my cousin sent me on the X2 and thought it had a supplemental wing.
It does not. But it overcomes the "retreating blade stall" problem by using coaxial, counter-rotating rotors.
Still, they've gotta be reducing the A.O.A. on the rotors at some point and using that pusher for thrust...
Therefore it's still not a true helo.

Sun Jan 16, 03:52:00 PM PST  
Blogger Bloviating Zeppelin said...

Greybeard, so yes, I suppose you could term it a compound instead of a true purist's helo. I can see that.


Sun Jan 16, 06:42:00 PM PST  

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