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unhappycamper Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 06:03 AM
Original message
Sikorsky: Ultra-fast helicopter in the works
unhappycamper note: Since the Pentagon (DoD? Gannett?) has requested that I only post one paragraph from articles on Army Times, and Airforce Times, To keep in that same (new) tradition, I will also do the same for for articles on Navy Times, Marine Corps Times, stripes.com and military.com.
To read the article in the military's own words, you will need to click the link.

Read all about Fair Use here. It sure is beginning to smell like fascism.

unhappycamper summary of this article: I wonder how much this thing is going to cost? The Osprey is around $100 million dollars. :(






The S-97 Raider will be based on Sikorskys prototype X-2 helicopter.


Ultra-fast helicopter in the works
By Dave Majumdar and Gidget Fuentes - Staff writers
Posted : Saturday Apr 23, 2011 8:47:37 EDT

The Raider would be more maneuverable than conventional helicopters and would accelerate faster, said Steve Weiner, the projects chief engineer. He also said it would be more adept at hovering than the mechanically and aerodynamically more complex V-22 Osprey.
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Bucky Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 06:18 AM
Response to Original message
1. Must be a prototype. I don't see any rocket tubes on the sides.
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denbot Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 06:25 AM
Response to Original message
2. Must be a concept proto type.
The osprey is a fairly large troop carrier
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Sherman A1 Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 06:34 AM
Response to Original message
3. Interesting design
but, actually looks like somethings we have seen in the past in basic concepts.
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FLPanhandle Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 07:00 AM
Response to Original message
4. This is an old concept but has been difficult to achieve
Edited on Sun Apr-24-11 07:06 AM by FLPanhandle
As explained to me by a helicopter pilot: With a single main rotor, the blades traveling with the direction of motion are moving through the air faster (generating more lift) than the blades rotating backwards. At high speeds this causes an imbalance that will eventually rotate the aircraft out of level flight.

With two counter rotating main rotors each side of the aircraft has a forward and backward moving blade balancing the effect.

Simple in concept but mechanically and with blade pitch control and air flow dynamics it's been a tough puzzle to solve. What's cool about this is that the concept will be applied to all future helicopters (commercial and military). Coast Guard helicopters will be able to get on scene much faster and return much faster.
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TheMadMonk Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 07:49 AM
Response to Reply #4
6. More than that. At high speed, the blade moving forward can easily...
...exceed the speed of sound.

Before that, when the chopper's forward speed matches the tip speed of the rotors, ALL lift is lost on that side.

The article doesn't say, but I think at speed the rotors are locked in place. This thing looks to be quite a mongrel: part chopper, part gyrocopter, part fixed wing plane.
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FLPanhandle Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 07:58 AM
Response to Reply #6
7. The blades wouldn't have to be locked necessarily
The could just slow the rotation down as the speed increases. The lift from the blades at high speed on both sides would still be sufficient with a slow rotation.

Good point on keeping the blades below the speed of sound.
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TheMadMonk Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Apr-25-11 01:58 AM
Response to Reply #7
17. At some point the lift generated by the rotors' forward motion will...
...completely overshaddow rotational lift.

At that point the most stable configuration would be to lock the rotors in an X configuration. With one rotor providing lift with two blades on one side and the other, with two blades on the other. If the blades could be rotated through 180 degrees it would become possible to generate lift on all eight surfaces.

On the other hand two and two makes for a safer descent in the event of losing power.
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originalpckelly Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 08:29 AM
Response to Reply #6
11. Actually, that happens all the time.
That's why you hear a beating sound. It's really the tip of the rotating wing breaking the sound barrier.
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TheMadMonk Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Apr-25-11 01:34 AM
Response to Reply #11
16. What might be fine for the tip is not fine for ten feet of blade. /nt


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jmowreader Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Apr-25-11 04:00 PM
Response to Reply #4
19. It hasn't been THAT difficult to achieve...
Google "Kamov helicopters." The Russian Kamov works builds all their helicopters this way, and they build a lot of helicopters.

It is possible Sikorsky will license the Kamov system because they've already got it working.
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leveymg Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 07:02 AM
Response to Original message
5. Merger of pusher-type turboprop with conventional fast helicopter. Back to the future
Edited on Sun Apr-24-11 07:14 AM by leveymg
Vietnam-era Lockheed AH-56 Cheyenne gyrodyne did 250 mph. Not clear why it was never put into production.



Here's an article you might enjoy. "The Quest for the 300mph helicopter": http://www.wired.com/dangerroom/2008/12/the-quest-for-t...
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unhappycamper Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 08:05 AM
Response to Reply #5
8. Simple answer: $$$$$$$ n/t
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leveymg Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 11:06 AM
Response to Reply #8
15. Here's an article on flexible and variable span rotors you may find interesting
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originalpckelly Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 08:28 AM
Response to Reply #5
10. Gyrodyne's and what's been presented are different.
You will notice the rotating wing is the only lifting surface the Sikorsky has, it's a real helicopter. A gyrodyne is a hybrid between a real plane and a rotating wing craft, notice in the picture how the Lockheed has wings? That's why it's a gyrodyne.

The article you linked to is not accurate in calling the vehicle a heli.

However, if you watch a video about the x2, you will note it just has rotating wings.

It's fascinating, but I have to wonder if the damn things won't want to fly into each other.

It will be cool for a while, but it will be hell to maintain if it goes near top speed often, because there will be immense wear on the sides where the rotors produce the most lift. Looks cool, but how will it actually work?
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leveymg Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 08:35 AM
Response to Reply #10
13. If the majority of thrust is produced by the tail prop, the main rotors won't need to spin so fast,
Edited on Sun Apr-24-11 08:38 AM by leveymg
avoiding the potential wear problem you mention. In flight, the main rotors wouldn't need to spin at all if the wing surface folded out and were big enough. I imagine it would work that way - what surprises me is that this hybrid system hasn't been further developed. No reason why one these things can't be high-subsonic.
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originalpckelly Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 08:19 AM
Response to Original message
9. I think this is a great thing...
but I'm not so sure the method by which they are producing counter-rotation is any simpler mechanically than the drive shaft connecting the two engines of an Osprey.
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leveymg Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 08:30 AM
Response to Reply #9
12. Counter-rotating rotors are nothing new - 1957 Cessna Grasshopper
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Motown_Johnny Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Apr-24-11 08:41 AM
Response to Reply #12
14. this one has a pusher, which I assume accounts for the acceleration
and possibly the top speed also



I just don't know if a somewhat faster helicopter has a niche to fill. They will never be anywhere near as fast as a fixed wing aircraft and they are already much faster than any ground or sea based craft.


I guess only time will tell.
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TheMadMonk Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Apr-25-11 02:27 AM
Response to Reply #14
18. Flown like a gyrocopter from a runway you could cram a fair load...
...onto one of these.

A simply somewhat faster heli alone? Possibly not. One that flies faster, can be overloaded and flown like a plane? That can be flown like a plane at any time the opportunity presents to significantly reduce fuel consumption? THAT I can see taking off.
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