Assault on Bin Laden: mystery of the downed chopper

Scott Kenny said:
And a link to the 1978(!) report about designing a stealthy helicopter: https://apps.dtic.mil/dtic/tr/fulltext/u2/a058906.pdf
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Posted in this thread in 2012:

I recall it was posted here before that as well but can’t find it.

The Mystery Machine has nothing to do with that 1978 study.

One of these days - long after a certain tabloid website is gone - I’ll write up the parts of the development story I know (and have verified).
 
quellish said:
Posted in this thread in 2012:

I recall it was posted here before that as well but can’t find it.

The Mystery Machine has nothing to do with that 1978 study.
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Huh, how'd I miss that when I binged this thread?

I still expect the Mystery Machine to have some gross shape relationships to the original study (I'm guessing shape 3, shape 2 has way too much of a performance penalty), though I would bet that they used a much more sophisticated computer version for the finer detail shaping.


quellish said:
One of these days - long after a certain tabloid website is gone - I’ll write up the parts of the development story I know (and have verified).
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And I will happily read it!
 
I still find it very interesting that despite extensive modifications to the tail, the main rotor seems to be very conventional. It has few differences, if any, from a standard Blackhawk 4-blade rotor:


While there are rotor head covers, etc. that were destroyed by demolition charges the remaining hub/head and rotors do not seem to have any major modifications. This is surprising, as usually for a quiet or LO helicopter you want more blades (5, 6) and unconventional shaping - like on the tail rotor.
 
Perhaps the four rotor blades were of "exquisite" design (?)
 
yasotay said:
Perhaps the four rotor blades were of "exquisite" design (?)
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Must have been.

When the story first broke, I assumed that they used an H-3 transmission and rotor head with Blackhawk blades. 5 blades on the head, but being spun at about 220rpm instead of 300.
 
Don't forget the hot and high aspect of the mission that day. They might have options to relax LO with conventional hub rotor to better dynamic performances.

However, I think that a rotor that is trimmed to match known radar frequency and aspect ratio would de-facto present the best stealth means to defeat RCS. It's quite similar to a rotor or prop that appears static or slow turning in a camera.
 
TomcatViP said:
Don't forget the hot and high aspect of the mission that day. They might have options to relax LO with conventional hub rotor to better dynamic performances.

However, I think that a rotor that is trimmed to match known radar frequency and aspect ratio would de-facto present the best stealth means to defeat RCS. It's quite similar to a rotor or prop that appears static or slow turning in a camera.
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Gotcha.

And speaking of the bolded part, have you seen the video of a Hind where it looks like the main rotor is completely stopped due to shutter speed perfectly matching the rotation?
 
bob225 said:
Sandbox has also done a couple of videos, i've not had time to watch as yet, so not sure of quality:
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I watched one of them. Nothing new or interesting. I didn’t get the impression there was much research done beyond a few Google searches.
 
quellish said:
I watched one of them. Nothing new or interesting. I didn’t get the impression there was much research done beyond a few Google searches.
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I watched them all, thats time i'll never get back.

He makes claims but does not provide the evidence, much like the articles sadly.

Not really worth the watch, sorry all!
 
quellish said:
I watched one of them. Nothing new or interesting. I didn’t get the impression there was much research done beyond a few Google searches.
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Certainly was the case on the one he did exposing me as suffering from a temporal shift something or other. A very shouty man. Maybe take some presentation tips from the Tank Museum or The Chieftain.

Chris
PS anyone got the right time?
 
Q-nimbus said:
View: https://youtu.be/8bRzSYsAmGI?si=WQZrfP8UwXazPKwH


In this video you can see a C-130 in a civilian colour scheme flying at Tonopah Test Range that is believed to be attached to JSOC:

https://www.scramble.nl/planning/or...merica/usaf-conus-southern-east-coast#KPOB284

Now I’m speculating of course, but I think that a JSOC C-130 at TTR is there for one thing only: to pick up a SSSHHH-Hawk.
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The civil C-130 is operated by a contractor that provides services to anyone. Just because it may have been used by JSOC at some point doesn’t mean it was working for JSOC at TTR. If I recall correctly it was running a flight test campaign for a small company.
 
quellish said:
The civil C-130 is operated by a contractor that provides services to anyone. Just because it may have been used by JSOC at some point doesn’t mean it was working for JSOC at TTR. If I recall correctly it was running a flight test campaign for a small company.
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Thank you for the additional details. Whoever operates it, it has no registration/tail number. Only US government planes are allowed to fly around with no tail number, so it’s definitely owned by some government agency.

There aren’t many aircraft with no tail numbers around, and those that we do see are usually involved with something shadowy.
 
piko1 said:
lol and that's why many Lacota's are with CSAR equipment strange this statement is like say'n that Kaiowa's never got deployed ;D
plus EC145 in germany are owned by ADAC they have nothing to do with GAF you mean France's Sécurité Civile ( Direction de la Défense de la Sécurité Civile (Department of Civil Defence and Emergency Preparedness) )


i have one question can we assume that the real designation of the "Stealth Hawk" is UH-69
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The Rage against the UH-72.....
 
Q-nimbus said:
Thank you for the additional details. Whoever operates it, it has no registration/tail number. Only US government planes are allowed to fly around with no tail number, so it’s definitely owned by some government agency.

There aren’t many aircraft with no tail numbers around, and those that we do see are usually involved with something shadowy.
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If you're not crossing international borders, you are only required to have 2" tall tail numbers, and can put them in places where they're hard to see.
Example: most warbirds painted in WW2 markings hide their tail numbers in the shadow of the horizontal stabilizer.​
 
I wonder how someone can visualize the Ghost Hawk without ever having seen one except a small part of the tail.
 
quellish said:
Based on the tail there are some reasonable assumptions someone informed can make about the rest of the aircraft.
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I don’t agree that you can make reasonable assumptions. It’s more like an educated guess. It’s a subtle difference but a difference nonetheless.

Most of the visualizations I’ve seen of the Ghost Hawk are done with the assumption that it’s stealthy as in difficult to see by radar.

I think that assumption is wrong. I’m sure they’ve put on some RAM-paint, shielded some inlets and exhausts, to reduce it’s overall RCS and infrared signature, but the main thing about the Ghost Hawk is that it’s very stealthy as in being very quiet.

A helicopter will never be truly stealthy unless they’ve figured out a way to make rotor blades completely radar transparant while still having anti/de-icing systems on them, and significantly reduce the amount the leading edges of the blades move vertically (you’d want to avoid as much horizontal movement of the blades as well, but well…).

I don’t think such a rotor exists, or if it does, comes somewhere near to the performance of a regular rotor.

I saw some Israeli Black Hawks on a nighttime raid in Syria one day, and they were just normal Black Hawks. It was a daring raid on a very well defended rocket factory.

That the Israeli’s haven’t modified them to be more quiet and stealthy tells me that the decrease in noise and RCS isn’t worth the amount of aircraft performance you loose. Which is basically what we’ve seen in Abottabad.

It’s been almost 15 years since that daring raid. The Chinese and Russians surely have managed to learn a lot from the leftover tail. Surely they won’t risk to much by declassifying the Ghost Hawk after all these years?
 
I agree with @Q-nimbus. The modified tail rotor was likely done to deal with the most noise propagating element of the Blackhawk helicopter. The significant noise associated with the interaction of the tail rotor with the main rotor wake is one of the largest noise generators. While the shield over the new tail rotor system likely has some radar reflective properties it might also be there to mask the high speed whine of the tail rotor gear box which is also a very prevalent noise maker. The downward swept tips of the main rotors, likewise changes the angle of the rotor vortices off the rotor blade and thus makes it a lower acoustic signature. Although, I suspect it does not help radar signature much. The low frequency, and thus long distance, detectable noises from the H-60 is the aircraft machinery and engines; the transmission gearing, engine oil cooler, engine turbine blades (from the front), triple redundant hydraulics, generators. All of these can be masked to an extent with sound proofing. I am sure this would make maintenance a nightmare, but since this is an aircraft that flies far less frequently and on nationally directed missions, it would be a price of admission. If you can engineer a multi-speed rotor systems into the aircraft even more sound reduction is possible.
Radar is just not something VTOL platforms with open rotors are going to overcome. Rotating blades big and small, hiding from multi-frequency radars is just not going to be made invisible. The good news is the very same sort of people who make those radar so keen, also make mission planning systems that help make and adapt routes in real time through air defense systems. Then there are jammers and missile defeat systems on most high end SOF type aircraft. Of course having friends in nondescript office buildings far from the action who can tell the air defense network "these aren't the helicopters you are looking for" helps too.
The remaining aircraft in question, if there is one, is likely now sitting in some secret squirrel museum under a mountain in Nevada. Besides helicopters are soo 20th Century. Bet we are using magnetically levitating carbon fiber "Doritos" now that drop robo-spider commandos silently in to do the non-attribution missions.

Alas @Q-nimbus - you only have 35 years to wait before mission declassification might happen. But the SOF types like to keep their secrets.
 
yasotay said:
I agree with @Q-nimbus. The modified tail rotor was likely done to deal with the most noise propagating element of the Blackhawk helicopter. The significant noise associated with the interaction of the tail rotor with the main rotor wake is one of the largest noise generators. While the shield over the new tail rotor system likely has some radar reflective properties it might also be there to mask the high speed whine of the tail rotor gear box which is also a very prevalent noise maker. The downward swept tips of the main rotors, likewise changes the angle of the rotor vortices off the rotor blade and thus makes it a lower acoustic signature. Although, I suspect it does not help radar signature much. The low frequency, and thus long distance, detectable noises from the H-60 is the aircraft machinery and engines; the transmission gearing, engine oil cooler, engine turbine blades (from the front), triple redundant hydraulics, generators. All of these can be masked to an extent with sound proofing. I am sure this would make maintenance a nightmare, but since this is an aircraft that flies far less frequently and on nationally directed missions, it would be a price of admission. If you can engineer a multi-speed rotor systems into the aircraft even more sound reduction is possible.
Radar is just not something VTOL platforms with open rotors are going to overcome. Rotating blades big and small, hiding from multi-frequency radars is just not going to be made invisible. The good news is the very same sort of people who make those radar so keen, also make mission planning systems that help make and adapt routes in real time through air defense systems. Then there are jammers and missile defeat systems on most high end SOF type aircraft. Of course having friends in nondescript office buildings far from the action who can tell the air defense network "these aren't the helicopters you are looking for" helps too.
The remaining aircraft in question, if there is one, is likely now sitting in some secret squirrel museum under a mountain in Nevada. Besides helicopters are soo 20th Century. Bet we are using magnetically levitating carbon fiber "Doritos" now that drop robo-spider commandos silently in to do the non-attribution missions.

Alas @Q-nimbus - you only have 35 years to wait before mission declassification might happen. But the SOF types like to keep their secrets.
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Loved the Star Wars reference.

I just hope, naively maybe, that the airframe that was involved in the most famous raid of the century sometime will get put on display.
 

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