Assault on Bin Laden: mystery of the downed chopper

[Mr London 24/7]

Couple of different images from Reuters, better view of Diamond shaped aperture on top of Tail:

 

[quellish]

This is the narrative so far:

* 24 in the primary assault group
* 80 "commandos" total. Not clear if this includes aircrew on the MH-47, CSAR assets, etc. Likely includes the 24 in the primary assault force.
* Force included tactical SIGINT (ISA), collection team, and "navigators"
* Assault launched from either Jalalabad, Afghanistan, or Ghazi, Pakistan. "Official" reporting is Afghanistan, but it is still possible that it was launched from Ghazi.
* 2 MH-47s as "backup"
* 2 "Modified blackhawks" for the primary assault force. The "modified blackhawks" may be conventional news outlets sourcing a AvWeek story which sources SPF.
* After the loss of 1 assault helicopter, the aircraft was demolished and the orphaned assaulters used one of the MH-47s for exfil.

So given the above, the two "stealth helicopters" flew in with some very unstealthy MH-47s. If the assault launched out of JBad, the SHHHHHH-60s would likely have refueled at some point. A stealthy in flight refueling boom would be an interesting challenge, but a FARP is another possibility.
Given the number of persons in the assault force, and the requirements to conduct an assault like this, the transport capacity seems thin. Since the lessons of EAGLE CLAW US special operations forces have not made it a practice to under resource an assault. It's likely there were more backup assets, that the helicopters were not near max capacity, and that there was replication within the assault force. The loss of an assault helicopter (and its operators) was almost certainly planned for, so it's possible there were additional SHHHHHH-60s. On the ground observers only saw/heard 4 helicopters, though obviously this is not very reliable information. They were stealth helicopters

There are a few possible organizations that could operate a SHHHHHH-60:
* AFSOC
* TF160
* JSOC Aviation SMU(s)

There are a limited number of places you could realistically flight test a low observable helicopter:
* NTS
* Eglin AFB
* Pax river

Specifically for this assault there were two training locations set up, one in the Western US and one in the Eastern US. It's likely that this was NTS and Eglin, but could have been several other locations (China Lake, Chocolate Mountains, Ft. Campbell, Ft. Bragg). A mockup of the compound was also constructed at Bagram. NTS and Eglin have both been used for this type of rehearsal several times in the past.

A helicopter that has a reduced radar signature is an interesting challenge, and very different from a fixed wing aircraft.

 

[Stargazer]

New pics are a confirmation for me that there seem to be two distinct tail units in the debris: one that is smooth and looks more like a mockup than an actual helicopter tail (the one in most pictures) and one that was darkened by the destruction of the damaged helicopter and is crooked. The former is the one that was found outside the precinct; the latter presumably lay on the inside. This to me points towards a possible collision between two choppers... But I'm willing to be proven wrong if some conclusive evidence/convincing explanation is shown.

 

[quellish]

New pics are a confirmation for me that there seem to be two distinct tail units in the debris: one that is smooth and looks more like a mockup than an actual helicopter tail (the one in most pictures) and one that was darkened by the destruction of the damaged helicopter and is crooked. The former is the one that was found outside the precinct; the latter presumably lay on the inside. This to me points towards a possible collision between two choppers... But I'm willing to be proven wrong if some conclusive evidence/convincing explanation is shown.

I think some of that may be from attempts to move the debris.

 

[quellish]

http://www.armytimes.com/news/2011/05/army-mission-helocopter-was-secret-stealth-black-hawk-050411/

 

[bcradio]

larger images of previous posted photos here:

http://www.guardian.co.uk/world/gallery/2011/may/04/osama-bin-laden-compound#/?picture=374256184&index=1

 

[Ian33]

http://www.armytimes.com/news/2011/05/army-mission-helocopter-was-secret-stealth-black-hawk-050411/

Quellish, you the man!.

Now I wonder if they have got a stealthy shroud for the refueller probe shaped like the F-117 pitot tubes? (yes I did read the article lol, but just thinking of advances made could of given modern versions the capability perhaps). Looking forward to pictures now.

 

[tacitblue1973]

Same tail pics, just a bit better

http://cryptome.org/eyeball/reuters-dead/reuters-dead.htm

 

[quellish]

Same tail pics, just a bit better

http://cryptome.org/eyeball/reuters-dead/reuters-dead.htm

The photo of the rotor assembly and what is left of the transmission should allow any Blackhawk crew dog to tell definitively if this was indeed a modified UH-60 or something else.

There has not been much so far that indicates it was, and experience tells us that to get a useful signature reduction it's best to start from scratch. Some things are just impractical with a modification anyway. For example, the UH-60 main landing gear would be difficult to conceal with a snap-on kit.
Of course, your biggest return is still going to be the rotor.

 

[bobbymike]

Speculation on the differences between regular UH-60 and 160th SOAR version, from defensetech.org.

http://defensetech.org/2011/05/04/what-the-secret-bin-laden-raid-helo-might-look-like/

 

[Gridlock]

On the ground observers only saw/heard 4 helicopters, though obviously this is not very reliable information. They were stealth helicopters

ABC News are reporting that locals only heard helicopters "when the were overhead" which of course negates neither stealth-then-unstealthy or all-stealthy hypotheses. But predictably both electricity and cell services went and came back for the duration of the mission, so I'd be fairly confident saying that Pakistani air defence radar was plagued by glitches that evening (ideally unnoticed ones).

There are a limited number of places you could realistically flight test a low observable helicopter

During the day, sure. But who operates interesting stuff during the day if they can avoid it? And the whole world is used to having police or ambulance or executive helicopters overhead, so I'd bet you could fly this thing round happily and only ever worry about the odd report surfacing.. And there have been odd reports of silent helicopters for years, of course. Even around Waco IIRC.

Are there any attributes of LO rotors that would increase the chances of encountering VRS?

 

[Gridlock]

If the radar-evading technology worked, it “would be a true statement” to say that the use of the low-observable Black Hawks was evidence that the United States gave Pakistani authorities no advance warning of the mission, the retired special operations aviator added.

If you want to play High Stakes Military Operations then I'd suggest flying an attack formation of aircraft towards the largest training academy of a nuclear power that is for all intents and purposes at war with a nuclear neighbour pretty much counts as an all-in.

You have to look at this operation in the context of there being at least 2 components to "Pakistan": the government and the military/ISI. The former likely knew about this mission, if only one or two people, but the latter (which fairly obviously has been playing either landlord or jailer these past 6 years - Occams razor again) could not know.

So either you roll out every last black program you've got to ensure you perform the least subtle assassination in recent times or you inform the government in advance but agree to say you didn't, for domestic reasons. I'd assume in this instance we got some semi-black helicopters and some very black phone calls.

I bet Obama took a big old slug of whisky when the aircraft went feet wet and nobody tried to start a nuclear war on the subcontinent.

 

[bobbymike]

If the radar-evading technology worked, it “would be a true statement” to say that the use of the low-observable Black Hawks was evidence that the United States gave Pakistani authorities no advance warning of the mission, the retired special operations aviator added.

If you want to play High Stakes Military Operations then I'd suggest flying an attack formation of aircraft towards the largest training academy of a nuclear power that is for all intents and purposes at war with a nuclear neighbour pretty much counts as an all-in.

You have to look at this operation in the context of there being at least 2 components to "Pakistan": the government and the military/ISI. The former likely knew about this mission, if only one or two people, but the latter (which fairly obviously has been playing either landlord or jailer these past 6 years - Occams razor again) could not know.

So either you roll out every last black program you've got to ensure you perform the least subtle assassination in recent times or you inform the government in advance but agree to say you didn't, for domestic reasons. I'd assume in this instance we got some semi-black helicopters and some very black phone calls.

I bet Obama took a big old slug of whisky when the aircraft went feet wet and nobody tried to start a nuclear war on the subcontinent.

You're giving Pakistan a lot of credit for command and control. As you point out the government/military/ISI are sometimes at odds with each other I guarantee they didn't give the SOCOM flight a second glance. They had no idea what was going on. To think that some helicopters would cause them to start hurling nukes around, please.

Mexican military helicopters have violated Texas airspace numerous times. The US military had no idea until they investigated civilian eyewitnesses on the ground in Texas and still would not say for sure that it happened.

 

[Gridlock]

To think that some helicopters would cause them to start hurling nukes around, please.

I suspect you are unfamiliar with just how close those 2 countries have been to a nuclear war in the past, and how often, and how recent. The Mumbai attacks almost got that far, thanks to telephone number spoofing...

http://www.dailymail.co.uk/news/worldnews/article-1092878/Hoax-phone-brought-India-Pakistan-brink-nuclear-war-height-Mumbai-attacks.html

http://yorkshire-ranter.blogspot.com/2008/12/howto-spoof-pakistani-foreign-ministry.html

There's a retired american official whose name I frustratingly can't recall (Lawrence Wilkerson, perhaps, but I suspect not) that is widely credited with stopping one, too. As in, it was going ahead.

My point is that getting in undetected is never 100% guaranteed, and if detected it would look very very hostile, and could easily trigger Instant Sunshine. Hence High Stakes. And hence my conclusion that we've got a semi-black SHHHHH-60 rather than anything truly black, which would be saved for proper wars and destroyed a lot more thoroughly if it crashed.

 

[quellish]

ABC News are reporting that locals only heard helicopters "when the were overhead" which of course negates neither stealth-then-unstealthy or all-stealthy hypotheses. But predictably both electricity and cell services went and came back for the duration of the mission, so I'd be fairly confident saying that Pakistani air defence radar was plagued by glitches that evening (ideally unnoticed ones).

There may be evidence out there to the contrary. Something like video recorded on a cellphone. There was video from the tail end of the assault that showed the burning helo. I have only seen it used as the background/inset in 4N newscasts.

During the day, sure. But who operates interesting stuff during the day if they can avoid it? And the whole world is used to having police or ambulance or executive helicopters overhead, so I'd bet you could fly this thing round happily and only ever worry about the odd report surfacing.. And there have been odd reports of silent helicopters for years, of course. Even around Waco IIRC.

You don't flight test at night. That's why we have places like the National Classified Test Flight Facility - to allow sight sensitive programs a place to flight test safely during the day.

Are there any attributes of LO rotors that would increase the chances of encountering VRS?

There are at least several techniques I have heard of for reducing the acoustic signature of rotors, and two for reducing the radar signature. The 1960s CIA aircraft used more, shorter blades, and part of the effect was due to the how the blades interacted.
The Air & Space article on the Hughes 500P "Quiet One" aircraft the CIA used in the 60s goes into this:
"The slapping noise that some helicopters produce, which can be heard two miles away or more, is caused by "blade vortex interaction," in which the tip of each whirling rotor blade makes tiny tornadoes that are then struck by oncoming blades. The Quiet One's modifications included an extra main rotor blade, changes to the tips on the main blades, and engine adjustments that allowed the pilot to slow the main rotor speed, making the blades quieter"
http://www.airspacemag.com/military-aviation/the_quiet_one.html?c=y&page=2

Helicopters with these modifications had performance limitations. Quieting the rotors with the above techniques cut into altitude, lifting capacity, and the ability to generate lift quickly - so yes, a quiet rotor could make an aircraft more susceptible to vortex ring state. The rotor - I am told - has much less "bite" when you need it.

 

[quellish]

Saw this a few weeks ago while looking for something else, only remembered it this afternoon:

"Low observable engine inlet system"
United Technologies Corporation
http://www.google.com/patents/about?id=7RQpAAAAEBAJ
(same, with citations)
http://www.google.com/patents/about?id=yOUdAAAAEBAJ
This probably applies more to the Comanche than anything else.

 

[Stuka]

Good point about slowing the rotor and VRS. Also, if the main rotor is slowed for acoustics then the tail rotor would be slowed in the same proportion. The tail rotor on the vehicle looks smaller and would have a higher disk loading and only a modest increase in solidity. The tail rotor would probably need to be sped up. This would point away from a simple bolt on kit unless an entire new tail pylon is bolted on at the tail fold hinge. A change in gear ratio might explain the seemingly oversize gearbox fairing compared to standard.

 

[Grey Havoc]

There is speculation on a number of sites that our mystery bird is a descendant of the 1980's MH-X program. Also the speculation about a RPG being responsible for the 'mechanical malfunction' isn't going away just yet.

http://www.globalsecurity.org/military/systems/aircraft/mh-x.htm

(Subscription might be required.)

 

[Michel Van]

here another Picture of the destroyed chopper

found on Spiegel.de
Source: Reuters

 

[quellish]

Following the money, and a serial number, has lead interesting places. It seems the First Rotary Wing Test Activity never really went away.

The Technical Applications Program Office and the Aviation Applied Technology Directorate both were part of an acquisition program that seems to resulted in several contracts, one of which can be linked to a part made in 2009 which is now in a field in Pakistan. The operator, though, maybe have been another tenant at Ft. Eustis which I had thought long dead, but is now apparently part of JSOC.

Now that I have access to EC2 again, I was able to do some work tonight. Unfortunately the images in the public domain are not as "good" as those of the J-20 first flight, which made the process more time consuming. After some fits and starts though I was able to perform a simulation of the shaping of the "gearbox" area at the tail rotor.
I was not certain before this wether the aircraft was really designed to have a lower radar signature or wether it was only "quiet". It does have a reduced radar signature, though from the rear aspect - like the AGM-129.

 

[Dragon029]

Perhaps another small hint?

 

[Grey Havoc]

Our rivals at militaryphotos.net have dubbed our mystery chopper "Geronimo".

 

[Stargazer]

Our rivals at militaryphotos.net have dubbed our mystery chopper "Geronimo".

Oh dear. "Geronimo", besides being the codename for Bin Laden,was also... an Apache!

 

[Grey Havoc]

Oh dear. "Geronimo", besides being the codename for Bin Laden,was also... an Apache!

;D

On another note, a question; does anyone here have anything on proposed drone variants of the Cobra? It's just some of the speculation on a second chopper going down outside the compound got me thinking.

EDIT: I thought of a, perhaps more fitting, name for our bird: 'Anasazi'.

 

[TomS]

I wouldn't get too hung up on those reports of two helicopters. It's probably an artifact of the very confused initial reporting where the Pakistanis were claiming it was a training accident or shootdown of one of their own helicopters. The fact that debris from the mystery bird ended up on both sides of the compound's wall probably contributed to the confusion.

Edit: it also looks like the Pakistanis really did lose a bird on Monday. That might also be contributing to the chaos.

http://www.daijiworld.com/news/news_disp.asp?n_id=100788&n_tit=Army+Chopper+Shot+Down+in+City+Where+Osama+Killed

 

[Grey Havoc]

I wouldn't get too hung up on those reports of two helicopters. It's probably an artifact of the very confused initial reporting where the Pakistanis were claiming it was a training accident or shootdown of one of their own helicopters. The fact that debris from the mystery bird ended up on both sides of the compound's wall probably contributed to the confusion.

Maybe. Although I wonder...

By the way, both MP and our humble site has gotten some credit from the Washington Post:

False alarm, WP only mentioned us indirectly via Defense Tech:

http://defensetech.org/2011/05/04/what-the-secret-bin-laden-raid-helo-might-look-like/

And here's is the latest version of Ugo Crisponi's sketch of what the 'Anasazi' ( ) might look like, from David Cenciotti's weblog:

 

[crusader97]

Has anyone else considered that this may be (at least partly) the outcome of the Senior Citizen program? Or possibly a less costly competitor? Everyone has assumed all along that SC was most likely a large delta shaped VSTOL aircraft at least in concept - but what if it wasn't that at all...just saying.

 

[Grey Havoc]

Has anyone else considered that this may be (at least partly) the outcome of the Senior Citizen program? Or possibly a less costly competitor? Everyone has assumed all along that SC was most likely a large delta shaped VSTOL aircraft at least in concept - but what if it wasn't that at all...just saying.

I'd go with the competitor theory.

 

[tacitblue1973]

The whole thing reminds me of the Sikorsky S-75 composite testbed, it had that kind of angular shape. Such an open program dovetailing into an SAP sound plausible?

 

[Machdiamond]

If this is a UH-60 derivative, the changes are more than skin deep.

Compare the rotor head pitch link attachment of the wreakage (top image) with one from the UH-60 (detail from a photo taken here http://www.b-domke.de/AviationImages/Rotorhead.html#Sikorsky.)

This is definitely different. It IS a Sikorsky helicopter, but it is quite different than the UH-60. Maybe it has one or two additional blades and the rotor hub has been entirely redesigned.

 

[pesholito]

If this is a UH-60 derivative, the changes are more than skin deep.

Compare the rotor head pitch link attachment of the wreakage (top image) with one from the UH-60 (detail from a photo taken here http://www.b-domke.de/AviationImages/Rotorhead.html#Sikorsky.)

This is definitely different. It IS a Sikorsky helicopter, but it is quite different than the UH-60. Maybe it has one or two additional blades and the rotor hub has been entirely redesigned.

I have to agree with Machdiamond. The rotor and spindles in particular look very similar. At least from what can be seen from the crash site picture. I am attaching an illustration of the spindles and the rotor hub and pitch controls.

 

[kingfhb]

http://www.wired.com/autopia/2010/02/eurocopter-moves-one-step-closer-to-whisper-mode/

Wikipedia has already added a new "Description" under their H-60 page based on the raid photos (MH-60 Black Hawk Stealth).
http://en.wikipedia.org/wiki/Sikorsky_UH-60_Black_Hawk

Also, the base that the 160th is attached to in Google maps has a large area of the tarmac "blanked out".

 

[Rhino62]

Is it likely that the US ordered the wreckage to be covered after the initial photos started to appear and while being hauled away, and did the US demand that remaining piece be retrieved and turned over to US forces?

 

[circle-5]

It is probable that news links to this topic have caused the 500%+ surge in SPF traffic today. We should all wear faceted stealth ties for our guests.

 

[quellish]

Is it likely that the US ordered the wreckage to be covered after the initial photos started to appear and while being hauled away, and did the US demand that remaining piece be retrieved and turned over to US forces?

Not likely. More likely that the authorities wanted to cover things for their own reason.
Destruction of the aircraft was SOP - you may recall that in "Blackhawk Down", the 2nd crash site was santized by the team that got to it after Shurgart and Gordon. Aircrews and operators are trained to clear IFF and radio codes and destroy a compromised helicopter. Blowing the SSSSHHH-60 had nothing to do with the technology, but everything to do with procedure.


Between 2000-2002 the Sikorsky "SVLO" group (Suvivablity and Low Observables) was working on an advanced development project under government contract. The funding levels involved indicate that this was more than a study. The project involved both acoustic signature reduction and radar cross section reduction, and had at least one major breakthrough that prompted the allocation of additional money.

 

[htbrst]

Stupid question perhaps - What colour is was it painted ?

It seems to vary depending on the angle of the camera - can someone point me to another aircraft wearing a similar paint colour ?

 

[quellish]

Dog and pony show tomorrow:

http://tfr.faa.gov/save_pages/detail_1_0680.html

 

[geeshockbloke]

Colour? BBC are saying pearlescent silver!

http://www.bbc.co.uk/news/world-us-canada-13297846

Mark

 

[quellish]

Colour? BBC are saying pearlescent silver!

http://www.bbc.co.uk/news/world-us-canada-13297846

Mark

"They are confident the raid marks the first time that a stealth helicopter has been used operationally."

Not likely.

 

[flateric]

Stupid question perhaps - What colour is was it painted ?

IR-suppression topcoat color is hard to describe as you said, variations of grey with metallic shining
not unlike topcoat being used for Raptors, F-16s, some specific V-22s tailnumbers