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S97 Raider

Old 3rd Aug 2017, 19:27
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Originally Posted by The Sultan View Post
History repeating itself?
The first S-69 built (73-21941) first flew on July 26, 1973. However, it was badly damaged in a low-speed crash on August 24, 1973 due to unexpected rotor forces and insufficient control systems.[2] The airframe was then converted into a wind tunnel testbed






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Old 3rd Aug 2017, 21:17
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Originally Posted by Nige321
The diamond shape 'vehicles'...?
S-75 ACAP?



I/C
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Old 3rd Aug 2017, 23:33
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Ian,

I think Nige321 meant this Diamond shaped contraption:

IMG_8568.PNG

Area 51B?

Cheers 5lB
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Old 4th Aug 2017, 03:24
  #344 (permalink)  
 
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These shapes are highly reminiscent of the 'hopeless diamond' shape that eventually resulted in the F-117, albeit more evolved. Radar cross section test dummies for some high speed vehicle perhaps?
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Old 4th Aug 2017, 14:12
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The Sultan, not sure how much you have ever flown. I suffered an engine roll back in a single engine turboprop trainer. I have had an engine roll back (reduce RPM from flight RPM) in both an SH-2F and an SH-60B in flight. In each case use of the various emergency throttle/lock out procedures restored enough power to fly home without securing the engine. (The SH-60B NATOPS called a "a partial power loss" ... but it's the same thing).

While I've had engines fluctuate while in a hover, I've never lost one (though we certainly trained for that malfunction a lot in the sim ... )
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Old 4th Aug 2017, 14:16
  #346 (permalink)  
 
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@212man Based on the water filled ditch/canal in the background of the photo of the S-97 and the fire truck, and the overhead you presented, it looks like the road at the far right of the overhead you posted. Taxiways in that picture are marked very clearly, while the one in the photo with the fire truck has no markings.
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Old 4th Aug 2017, 18:26
  #347 (permalink)  
 
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Lone,

Point is the 97 is single engine so "an" engine (implies more than one) rolling back is not applicable. Very possible it puked the engine. Question remains with exception of a PR flight why was the gear up (as "confirmed" by articles) when hovering/low speed over a hard surface? They obviously were not doing HV/auto testing. I guess it is always possible they landed after forgetting to lower the gear, but not likely. On the 609 we had a special rig we could land on should the gear fail to extend, do not see similar here.
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Old 4th Aug 2017, 18:50
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The Sultan;9850996]It would be the engine.
I thought you had permanently disappeared after your last round of ill informed and totally factually incorrect bashing of the S-92 and individuals on this forum, but then again, maybe your Mother hasn't realized you're back here posting again yet?

It's possible that English isn't your native tongue, or simply that you have never mastered it?

Just for you.
https://en.oxforddictionaries.com/definition/an

It is "AN" engine failure. It is also "AN" engine roll back.
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Old 4th Aug 2017, 19:30
  #349 (permalink)  
 
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Pants

Common definition of "the": used with a singular noun to indicate that it represents a whole species or class.

Since their was only one completed S-97 with only one engine "the" is the proper determiner.
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Old 5th Aug 2017, 00:35
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You know there’s a lack of public information when we’re arguing over grammar, lol.
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Old 5th Aug 2017, 02:50
  #351 (permalink)  
 
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Grammar aside, one has to ask what the real issue is here.

The S-97 Raider has experienced a minor mishap after years of development with a very limited flight envelope. The lack of flight envelope expansion is the issue not this mishap.
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Old 5th Aug 2017, 03:20
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Looking at the S-75 ACAP - I see grandfather of Stealth-Blackhawk.
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Old 5th Aug 2017, 17:10
  #353 (permalink)  
 
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@Jack Carson: nicely put
@Sultan: I guess the both of us can drop the handbags now.

As to the damage, I guess it'll buff out.
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Old 18th Aug 2017, 19:50
  #354 (permalink)  
 
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Anyone hear any news about possible causes in the last couple of weeks? Component failure, computer/software issues, etc?

Perhaps it threw a pusher prop blade like the iron bird did a while back? Noticed in the videos some personnel far off to the 9 o'clock in the grass possibly looking for something
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Old 19th Aug 2017, 14:04
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Sans,
I have no idea, but am interested also. Tell us about this iron bird prop incident - did I miss the story somewhere? Did they have a dedicated iron bird?
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Old 21st Aug 2017, 15:21
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While shaking the proverbial trees among my industry peers for info on the Raider incident, I was told in passing about the tail rotor prop chucking a blade in the test pit on an iron bird rig a while ago.

Supposedly this was caused by some miscommunication regarding design loads with a supplier, and subsequently slowed progress as all changes were much more thoroughly scrutinized.

Same sources also relayed something that a lot of people have been suspecting - that the vibration is a large issue and the pilots were having difficulty reading displays in flight. Sounds like there is an internal belief that the fuselage may not be stiff enough.
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Old 22nd Aug 2017, 06:06
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Sans-

In this video of a tie-down run of the S-97 you can see how the pusher prop drive is de-clutched as the main rotors come up to speed. If my understanding is correct, doesn't the S-97 de-clutch the prop drive during hover? If so, I can see potential unanticipated vibration and dynamic torsional load issues in the prop drivetrain from friction clutch chatter while accelerating the prop up to speed from a stop. The dynamic torsional effects produced by friction clutch slip/chatter during engagement are very hard to accurately predict. Seems possible that the prop system failed due to operating loads higher than anticipated.

https://youtu.be/VBJZhPbMHlU
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Old 11th Sep 2017, 20:12
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S-97 Raider sustained ?substantial damage' in crash, but program moves forward

Most interesting takeaway is 20 flight hours in approx 2.5 years. Also explains where that 2nd prototype airframe has been.
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Old 11th Sep 2017, 23:31
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From the above referenced:

“The neighborhood of the root cause is the complex interaction between the ground, the landing gear, the flight control system and the associated pilot interactions,” he told a few reporters in a phone interview. “If you are familiar with the rotorcraft industry, this is a well-documented complex set of interaction as airplanes transition from operations on the ground to operations in flight.”
So pretty close to what caused them to crash the first XH-59A. It appears #1 is basically finished also like the 59A. You would think Sikorsky would have focused on near ground handling as a lesson learned from the previous program.

Does not bode well for this concept if you can not safely lift to a hover.
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Old 12th Sep 2017, 08:55
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complex interaction between the ground, the landing gear, the flight control system and the associated pilot interactions
Otherwise known as 'taking off and landing'!
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