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S97 Raider

Old 1st May 2017, 22:21
  #281 (permalink)  
 
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Originally Posted by IFMU
So, the X2 was a flexbeam rotor?
As if you didn't know...not exactly "A" (singular) flexbeam, more akin to a beefy composite TT strap or loop.

It really depends on what one considers a "flexbeam" semantically. In the traditional sense like an S-92 tail rotor, Comanche, or Bell 680/H1 style chicken foot yoke/flexbeam? No.

But if you pay close attention, you'll notice even Sikorsky refers to these types of multi-node structures as "flexbeams"

https://www.google.com/patents/US7695249

https://www.google.com/patents/US20150014476

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Old 1st May 2017, 23:13
  #282 (permalink)  
 
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Originally Posted by SASless
The 525 is doomed then I assume....as is the 609 and the Tilt Rotor based upon prototype crashes.

It was politics that was fatal to the Cheyenne....not aerodynamics!
I'm unconvinced about that. The political leadership did support a state of the art high end attack helicopter.
There was a consensus that there was a legitimate requirement, but no confidence that the Cheyenne's problems could be fixed. Hence the AH-64, to replace the Cheyenne.
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Old 2nd May 2017, 00:03
  #283 (permalink)  
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Originally Posted by etudiant
There was a consensus that there was a legitimate requirement, but no confidence that the Cheyenne's problems could be fixed. Hence the AH-64, to replace the Cheyenne.
You are making an incorrect historical omission. The Bell Cobra is the platform that fulfilled the Army's "legitimate requirement ". The Cheyenne was a technical marvel when designed, and would still be today. But could you ever imagine maintaining the complex beast in the rice paddies of South East Asia?

The Bell Cobra may not have been what the Army upper eschelon wanted, but it provided the grunts on the ground in Vietnam the machine they need for a decade before the Apache came around.
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Old 2nd May 2017, 01:36
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The Cobra was indeed in service at the time, no question. The Cheyenne was to be the clean sheet follow on, faster, more powerful and more capable.
The Apache was launched as a Cheyenne successor after that effort ran into technical problems.
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Old 2nd May 2017, 03:31
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Originally Posted by CTR
The Bell Cobra may not have been what the Army upper eschelon wanted, but it provided the grunts on the ground in Vietnam the machine they need for a decade before the Apache came around.
A goodly number of my colleagues who flew in the USMC likewise found the Cobra a capable platform.
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Old 2nd May 2017, 03:54
  #286 (permalink)  
 
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After a lot of improvements and growth over the years.
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Old 2nd May 2017, 11:44
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That Cheyenne doco is fascinating.
Forgive my ignorance - but I assume the Apache is ultimately a much more capable aircraft?
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Old 2nd May 2017, 13:41
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Originally Posted by tartare
That Cheyenne doco is fascinating.
Forgive my ignorance - but I assume the Apache is ultimately a much more capable aircraft?
IIRC not as fast, but plenty capable. (And it apparently does not have the problem of the blades coming through the cabin ...)
@SASless: IIRC, the Marines flew three (J, T, W) Cobra variants variations (twin engine) before the recent Z model (Viper) made a big change in what a Cobra is. Not sure if there was a single engine model mixed in there in the dim and distant past.
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Old 2nd May 2017, 14:02
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Back in the time of target designation being made by map coordinates given by a very scared guy on the ground (no gps) and either a smoke grenade or perhaps some tracers or muzzle flashes.....or at night tracers or verbal directions and visible light strobe lights/flashlights....there was some discussion as to the effect of having two pilots in an enclosed cockpit versus having two door gunners as well had on efficiency in acquiring targets.

With the advent of hi-tech means of locations, nvg's, FLIR, etc......the two pilot gunship has come into its own!

The USMC also uses their latest UH-1 for gunnery Support as I hear it.
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Old 2nd May 2017, 14:30
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Originally Posted by tartare
That Cheyenne doco is fascinating.
Forgive my ignorance - but I assume the Apache is ultimately a much more capable aircraft?
The Army accepted that the Apache would not match the Cheyenne performance. It has not closed the gap since, partly because the design is less capable, partly because weight growth has negated the gains from the improved power train and rotor.
It should be noted that the one attempt in Iraq to engage a large tank formation solely with Apache helicopters was not a success. It is doubtful that the Cheyenne would have done much better.
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Old 2nd May 2017, 15:13
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Apples to Oranges....the Cheyenne was '60's technology and only reached prototype status with three aircraft .

Perhaps that Apache thing was tactics/planning/intel failure generated rather than an aircraft failure!
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Old 2nd May 2017, 21:57
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Originally Posted by SASless
Apples to Oranges....the Cheyenne was '60's technology and only reached prototype status with three aircraft .

Perhaps that Apache thing was tactics/planning/intel failure generated rather than an aircraft failure!
No argument about the tactics failure, just that tactics need to adjust to reality and that is difficult to determine in exercises. The Army thought it had the answer, they were mistaken. Iirc, over 30 Apaches got badly shot up in that engagement.
Separately, the Cheyenne was much more advanced than the AH-64.
The combination of a pusher prop, a wing and a rigid rotor allowed much better acceleration and maneuverability than the Apache could offer. Technically, the Apache was two steps backward, but it was more powerful and safer than the Cobra, which was what the Army wanted.
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Old 2nd May 2017, 22:17
  #293 (permalink)  
 
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More roles envisaged for the S-97

http://aviationweek.com/defense/us-a...hawk-successor



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Old 3rd May 2017, 01:53
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Originally Posted by SASless
The USMC also uses their latest UH-1 for gunnery Support as I hear it.
Oh yes, they do, and the typical two ship was one Cobra and one Huey when I was last in the area where hot lead was going down range for real. Goodness.
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Old 3rd May 2017, 01:56
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Originally Posted by etudiant
The Army accepted that the Apache would not match the Cheyenne performance. It has not closed the gap since, partly because the design is less capable, partly because weight growth has negated the gains from the improved power train and rotor.
It should be noted that the one attempt in Iraq to engage a large tank formation solely with Apache helicopters was not a success. It is doubtful that the Cheyenne would have done much better.
My friend, the Army Aviation folks spent the better part of two decades trying to convince our two dimensionally, ground bound, and limited colleagues that Army Aviation is a maneuver element not a combat support element nor a DS element like Artillery.

A friend of mine wrote a paper on the problems of the Army "getting" CAS and Rotary Wing aviation. It may be a bit dated, but the Army changes as slowly as any top heavy organization.

So, once they finally got that acceptance, they had to go an prove it. 11th paid a price for that. (How about let's give the Iraqi's a bit of credit for being a smart, thinking enemy in how they handled that ambush).
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Old 3rd May 2017, 02:02
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OK, I get the troop assault and the recon attack.

SAR?

FFS, let's give it a rest.
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Old 3rd May 2017, 05:49
  #297 (permalink)  
 
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I'm still in awe of the maneuverability and handling characteristics of the XH-51 in that video.
So - reading back through the thread - essentially you are all debating whether a rigid rotor co-axial design will effectively scale up to the size required by the Raider?
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Old 3rd May 2017, 17:04
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Originally Posted by tartare
So - reading back through the thread - essentially you are all debating whether a rigid rotor co-axial design will effectively scale up to the size required by the Raider?
I've debated the following:
  • The Raider is the upper limit of the ABC technology scalability that will still meet some of its performance goals versus conventional helicopters
  • Even at S-97 gross weight it will not perform the high-G maneuvers advertised (even X2 never demonstrated the same at 1/2 size)
  • A flyaway cost for S-97 would not come anywhere close to the purported $15 million price tag

The real feasibility challenge is scaling up 2X again to SB-1 size and meeting any of the maneuverability, speed, and cost targets.
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Old 3rd May 2017, 17:29
  #299 (permalink)  
 
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That mission variants graphic seems familiar.



Note, the 1973 version even includes the "autonomous" variant (RPV as it was back in those days).
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Old 3rd May 2017, 17:38
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Originally Posted by Lonewolf_50
OK, I get the troop assault and the recon attack.

SAR?

FFS, let's give it a rest.
Why? Without having given it much thought, using a fast compound for SAR doesn't seem like the worst idea.
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