Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: Thaeris on May 07, 2011, 02:01:11 pm
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I saw this on the news the other day - that of the assets used in killing Osama bin Laden, some of those assets included... low-observable Blackhawk helicopters?
Yep. Low-observable Blackhawk helicopters! And they would have remained as low-observable as helicopters can get if, you know, one of them didn't crash for undisclosed reasons. And while the main hull of the choppa' was demolished by SEAL Team 6, there was the unfortunate case of the tail rotor being on... the other side of the wall, where it could not be destroyed by the fury and explosives of those slippery SEALs...
The helo in question is an interesting example of technological evolution, and it seems to be the case that the basic hull of an H-60 was modified to accomodate better aerodynamics, reduced RCS, RAM, and acoustic-reduction technology. All that hard work which never got to be used on an operational RAH-66 Comanche went somewhere... and unfortunately that somewhere also includes Pakistan.
...Which probably also means that China will get it, too. This is not really a good thing for those of us in the Western world, as that technology will undoubtably be the subject of reverse engineering. Now, we'd certainly do the same if there was something of interest to us, but quite frankly, China doesn't need the help. Maybe none of us need that sort of help. But there you go. If we'd like to further discuss this topic, that would be fine and dandy, as there's plenty to discuss.
That said, the first thing any analysist needs: concept art!
(http://cencio4.files.wordpress.com/2011/05/mh-x3.jpg)
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(http://i56.tinypic.com/35mqdcy.jpg)
(http://i52.tinypic.com/25qggfl.png)
EDIT:
(http://i54.tinypic.com/63u9dw.jpg)
EDIT2:
(http://i56.tinypic.com/2466qtd.jpg)
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there was a bit of a discussion about it here
http://www.hard-light.net/forums/index.php?topic=75896.0
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Well, you can pick out a dielectric panel on top of the tail assembly, and there's more to the tail rotor shround than I thought - it's shielded on both sides. The rotors are smaller and shorter as well. It must be my eyes playing tricks on me, but those rear stabilizers almost look like they're swept forward as well! However, I doubt that to be the case.
For anyone reverse engineering the systems, the most interesting componets are bound to be (a.) the rotor blades and (b.) the RAM. The large shrouds on the 'Hawk here must principally be for covering the tail rotor mechanism, which is bound to be a high return source for hostile emitters. It might also help reduce the acoustic signature by preventing as large a mass of airflow from interacting with the mechanism. However, the main reducer of noise is bound to be the assumably sophisticated airfoils on the rotor blades themsleves.
That said, is there a shot of this thing from the side anywhere?
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I think that, whatever you can reverse engineer from the wreckage is limited to maybe a bit of the RAM coating applied to the hull. The general design principles aren't black magic (unlike, for example, a submarines prop design), and well.... designing a low-observability helo isn't black magic either, or THAT complicated when you get right down to it.
All in all, unlike the F117 that got shot down over Yugoslavia, the amount of actual leakage is really limited.
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Yep. Low-observable Blackhawk helicopters! And they would have remained as low-observable as helicopters can get if, you know, one of them didn't crash for undisclosed reasons.
Knowing US special forces the plan was probably to crash it into the compound all along.
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I think that, whatever you can reverse engineer from the wreckage is limited to maybe a bit of the RAM coating applied to the hull. The general design principles aren't black magic (unlike, for example, a submarines prop design), and well.... designing a low-observability helo isn't black magic either, or THAT complicated when you get right down to it.
All in all, unlike the F117 that got shot down over Yugoslavia, the amount of actual leakage is really limited.
Notice I wasn't placing too much emphasis on the hull shape. Anyone designing a purpose-built low-observable helo will understand fuselage shapes well enough. The mechanisms and the fine details, however, are the real engineering challenge. And yes, it IS that complicated. The biggest give-away of a chopper is the "chopping," if you will. If you can reduce the acoustic signature, you make a L-O helo that much more effective. So, in this instance, the prop designs are a pretty big loss for the US - in a way, it's no different than having the specs for s sub's props leaked. They follow the same basic principals, remember.
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Yep. Low-observable Blackhawk helicopters! And they would have remained as low-observable as helicopters can get if, you know, one of them didn't crash for undisclosed reasons.
Knowing US special forces the plan was probably to crash it into the compound all along.
If John McClane was indeed on the team that went in, this is probably what would've happened :colbert: (http://www.colbertnation.com/the-colbert-report-videos/383524/may-03-2011/osama-bin-laden-is-still-dead)
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Yep. Low-observable Blackhawk helicopters! And they would have remained as low-observable as helicopters can get if, you know, one of them didn't crash for undisclosed reasons.
Knowing US special forces the plan was probably to crash it into the compound all along.
If John McClane was indeed on the team that went in, this is probably what would've happened :colbert: (http://www.colbertnation.com/the-colbert-report-videos/383524/may-03-2011/osama-bin-laden-is-still-dead)
I just remember one of the elements of the big prison rescue attempt in Nam being smashing a helicopter right down into the compound.
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Yep. Low-observable Blackhawk helicopters! And they would have remained as low-observable as helicopters can get if, you know, one of them didn't crash for undisclosed reasons.
Knowing US special forces the plan was probably to crash it into the compound all along.
If John McClane was indeed on the team that went in, this is probably what would've happened :colbert: (http://www.colbertnation.com/the-colbert-report-videos/383524/may-03-2011/osama-bin-laden-is-still-dead)
If John McClane was involved there would only be rubble left of the house
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Notice I wasn't placing too much emphasis on the hull shape. Anyone designing a purpose-built low-observable helo will understand fuselage shapes well enough. The mechanisms and the fine details, however, are the real engineering challenge. And yes, it IS that complicated. The biggest give-away of a chopper is the "chopping," if you will. If you can reduce the acoustic signature, you make a L-O helo that much more effective. So, in this instance, the prop designs are a pretty big loss for the US - in a way, it's no different than having the specs for s sub's props leaked. They follow the same basic principals, remember.
Yeah, but still..... From my POV, this isn't really cutting edge tech. New implementation of known principles, sure, but nothing as fundamentally groundbreaking as the F117 or B2. There may be a few wrinkles there, but it all comes down to solutions for well understood problems.
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I'd personally also class a stealth Helo as something of a 'gimmick' piece of hardware. Whatever you do to a helicopter, it'll never be as quiet as a high-flying jet, and it'll never be as fast as a jet, making the applications for it beyond what a normal non-stealth helo can do somewhat limited. Basically, this raid was exactly the kind of thing you'd need a stealth Helo for, while in an actual war they'd be sidelined - All it takes to get one brought down is a guy with a set of ears and a phone.
And as such, whatever secrets were lost due to that tail rotor surviving, it probably isn't the end of the world. Besides, If the US were going to lose one, this raid was probably the place to do it, considering the value of the target.
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Notice I wasn't placing too much emphasis on the hull shape. Anyone designing a purpose-built low-observable helo will understand fuselage shapes well enough. The mechanisms and the fine details, however, are the real engineering challenge. And yes, it IS that complicated. The biggest give-away of a chopper is the "chopping," if you will. If you can reduce the acoustic signature, you make a L-O helo that much more effective. So, in this instance, the prop designs are a pretty big loss for the US - in a way, it's no different than having the specs for s sub's props leaked. They follow the same basic principals, remember.
Yeah, but still..... From my POV, this isn't really cutting edge tech. New implementation of known principles, sure, but nothing as fundamentally groundbreaking as the F117 or B2. There may be a few wrinkles there, but it all comes down to solutions for well understood problems.
Alright, now that might be kind of true, but let me re-iterate why loosing the mechanical parts here is a really big deal:
Helo blades effect so many things about a chopper: range, efficiency, noise signature, etc. Aerodynamically, rotor blades are the most important external design factor on a helo. And if it's L-O, those blades must also factor in dealing with RCS. So, you have a rotor blade which has tip velocities which very well may be gettting close to the supersonic, and you're trying to make it quieter. Next, let's assume you DO make it quieter, so you have a high efficiency, quiet rotor blade which has design characteristics which reduce RCS. Managing all of those factors and overcoming them by some margin is a TREMENDOUS design challenge. It may be built upon compound knowledge, but everything else is as well. Next, it's information the likely candidates for obtaining the information DO NOT HAVE. That said, it is again a really big deal.
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I'd personally also class a stealth Helo as something of a 'gimmick' piece of hardware. Whatever you do to a helicopter, it'll never be as quiet as a high-flying jet, and it'll never be as fast as a jet, making the applications for it beyond what a normal non-stealth helo can do somewhat limited. Basically, this raid was exactly the kind of thing you'd need a stealth Helo for, while in an actual war they'd be sidelined - All it takes to get one brought down is a guy with a set of ears and a phone.
And as such, whatever secrets were lost due to that tail rotor surviving, it probably isn't the end of the world. Besides, If the US were going to lose one, this raid was probably the place to do it, considering the value of the target.
Ever heard of the Q-Star (http://en.wikipedia.org/wiki/Lockheed_YO-3)? Where there's a will, there's a way. Submarines and slow aircraft can inherently be quieter due to the fact that they can have slower tip velocities on their props. But regardless, if you can make a quieter helo that's also harder to detect, you've got a one-up on a potential adversary. Now, the inevitable is that eventually that knowledge would become more commonplace, but a quieter helo blade is the key in making a L-O helo. There's a good chance that lead was just cut short now.
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The problem is, they only have the tail rotor. There are a bunch of techniques to make that one quiet, NOTAR and Fenestron assemblies say hello.
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And those are better design solutions, which also take some of the dangers out of the TR. This is certainly more a design upgrade of the Blackhawk, but it potentially reveals some of my concerns to powers which you and I would rather not see to have such data.
*EDIT
Keep in mind that NOTAR is less efficient than shrouded TR assemblies, and serious consideration of its use on a combat helo would need to be considered. It's also very demanding in terms of structural re-design.
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The point is, for me, this isn't likely to have any major impact. As Shade pointed out, low-observability helos are only effective under a limited set of circumstances. Knowing which particular route the US took to build these new Black Hawks is only academical; We all knew they had the tech to do it if they wanted to ever since the RAH 66. We also know of several other techniques to achieve the same design goals.
The only thing here that might be compromising is the RAM coating. But even that is rather minor, given that China almost certainly has a brand of those of their own.
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Well, I suppose that is a decent point. However, I think my point also is valid enough given the circumstances.
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I'd personally also class a stealth Helo as something of a 'gimmick' piece of hardware. Whatever you do to a helicopter, it'll never be as quiet as a high-flying jet, and it'll never be as fast as a jet, making the applications for it beyond what a normal non-stealth helo can do somewhat limited.
For that matter, in most cases low observability for a helicopter can be achieved in much simpler fashions, by hiding behind terrain features or simply going really, really slowly. Gulf One featured helicopters making initial penetration of Iraqi air defense by flying slow enough they were suppressed as ground clutter. Anybody can do that, and it will usually work.
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id bet this is kind of a stealth kit, that can be fitted to a standard blackhawk at short notice. i could easily imagine the composite panels being fastened directly to the aluminum skin of the chopper, then it would just be a matter of swapping the rotor head and tail for stealthy equivalents. this is somewhat reminiscent of how they used much of the uh-1 structure and mechanical components in the cobra back in nam. it seems it would be less costly do adapt an existing airframe for stealth than it would be to come up with something from scratch.
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Yep. I think I was pointing to that sentiment in a way in my initial post. However, I do not think this would be a mere field modification. You can't just put a different set of rotor blades on a helo without changing any of the internal mechanisms and expect everything to work perfectly. Of course, then you might argue that this is the reason for why one of them crashed. :p
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According to AW&ST (http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/05/09/AW_05_09_2011_p22-318890.xml), the crash:
was not a mechanical failure or a problem by the pilot that downed the Black Hawk—it was a miscalculation of temperature in and outside the compound. The Black Hawk ran into lift trouble due to a 15F difference inside the courtyard, says Rep. Buck McKeon (R-Calif.). “They couldn’t hold the hover.”
Cool stuff though. Stealth choppas...
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So wait, if these guys crashed their helo, how did they get home?
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So wait, if these guys crashed their helo, how did they get home?
They brought spares man.
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They redistributed the personnel among the other 3 Helos they brought along.
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According to AW&ST (http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/05/09/AW_05_09_2011_p22-318890.xml), the crash:
was not a mechanical failure or a problem by the pilot that downed the Black Hawk—it was a miscalculation of temperature in and outside the compound. The Black Hawk ran into lift trouble due to a 15F difference inside the courtyard, says Rep. Buck McKeon (R-Calif.). “They couldn’t hold the hover.”
Cool stuff though. Stealth choppas...
Didn't Deus Ex have stealth copters?
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Oh okay, for some reason I was envisioning this lone helo sneaking in with some small team of badasses, who then had to steal a local's car or something to escape. :p
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According to AW&ST (http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/05/09/AW_05_09_2011_p22-318890.xml), the crash:
was not a mechanical failure or a problem by the pilot that downed the Black Hawk—it was a miscalculation of temperature in and outside the compound. The Black Hawk ran into lift trouble due to a 15F difference inside the courtyard, says Rep. Buck McKeon (R-Calif.). “They couldn’t hold the hover.”
Cool stuff though. Stealth choppas...
Didn't Deus Ex have stealth copters?
yep there was a Comanche style design in the first game, though i am not sure if IW's helo was stealthy. though as a game it is slightly irrelevant to the conversation
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Yep. I think I was pointing to that sentiment in a way in my initial post. However, I do not think this would be a mere field modification. You can't just put a different set of rotor blades on a helo without changing any of the internal mechanisms and expect everything to work perfectly. Of course, then you might argue that this is the reason for why one of them crashed. :p
then learn how things work on a helicopter (twok reference, lol). the way helicopters work is somewhat elegant. tail rotor is directly geared to the main rotor. very little needs to be done here, though the tail rotor has some gear reduction to get it near where it needs to be to provide adequate thrust. its the pitch of the tail rotor blades that ultimately determine how much thrust the tail rotor puts out. this is what traditionally the antitorque pedals control, though in this case id expect a sophisticated fly by wire system to be somewhere in between. that said the blades dont need to change pitch by much to make the system produce a different level of thrust. so there is probably some calibration required to make it work, but thats hardly as complicated as swapping a rotor (and likely done automatically by the fbw system). that said the tail is usually less complicated than the main rotor, which also has to control yaw and pitch in addition to thrust. still its a matter of calibration.
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yeah, but I would doubt they brought in a normal black hawk to some base in Afghanistan glues some stealth panels and blades onto it and then went into battle with it. I have a funny feeling that this helicopter was purpose built for it's job. I'm sure 99% of it is a normal black hawk, but I doubt they started with a used one and turned it stealth.
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I'm not sure, Give a competent maintenance team a hanger, couple of days, the parts and the instruction manual and it should be doable
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Nuke, in general I think I'm decently versed in how a helicopter functions (though helicopters were never a great interest of mine). However, the internal systems a helo is designed with are directly related to external components. Any differences in rotor mass, lift characteristics, etc., would have an effect on flight performance if nothing else about the aircraft was changed. It's not impossible that this was a field modification, but it's just highly unlikely. Like others and myself have said, it's assumably just a new variant.
Note that internal changes include software (displays and FBW/SAS, if the aircraft has computer-augmented controls), mechanical elements (as you noted), etc., etc. Given the complexity of modern aircraft, again, a field mod is unlikely.
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So wait, if these guys crashed their helo, how did they get home?
They brought spares man.
Must've been hard, they probably needed that other helicopter just to transport their balls.
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So wait, if these guys crashed their helo, how did they get home?
They brought spares man.
Must've been hard, they probably needed that other helicopter just to transport their balls.
I belive extracting family mambers was part of the plan and they had to be left behind so all the soldiers could evac
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yeah, but I would doubt they brought in a normal black hawk to some base in Afghanistan glues some stealth panels and blades onto it and then went into battle with it. I have a funny feeling that this helicopter was purpose built for it's job. I'm sure 99% of it is a normal black hawk, but I doubt they started with a used one and turned it stealth.
i was thinking more along the lines of a hanger deck in one of those usmc helo carriers. easier to keep classified things classified that way. this also goes with the whole burrial at sea scenario as well.
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Nuke, in general I think I'm decently versed in how a helicopter functions (though helicopters were never a great interest of mine). However, the internal systems a helo is designed with are directly related to external components. Any differences in rotor mass, lift characteristics, etc., would have an effect on flight performance if nothing else about the aircraft was changed. It's not impossible that this was a field modification, but it's just highly unlikely. Like others and myself have said, it's assumably just a new variant.
Note that internal changes include software (displays and FBW/SAS, if the aircraft has computer-augmented controls), mechanical elements (as you noted), etc., etc. Given the complexity of modern aircraft, again, a field mod is unlikely.
i dont know about that. ive gone through 2 rotor heads and 3 tail assemblies on my rc helo so far. sometimes im supprised with how little ive had to do to get completely different systems to work on the same airframe and the same drive train. point here is that rpm is less important than blade pitch in controlling thrust. not to say that changing the rpm wouldn't have a huge effect, it would. but this tail rotor was likely designed to work at the same rpm as a standard blackhawk tail rotor, so that no changes to the gear ratio with the main rotor would be necessary to achieve the same thrust. the variables are rpm, surface area of the blades, length of the blades (tips go faster if they are on longer blades), number of blades, shape of the blades, etc.
for example the blades are smaller here, but theres 5 of them, instead of 2. the blades likely use a higher efficiency and/or low noise configuration. as a rule of thumb noisy machines tend to be inefficient machines. since so much energy goes into making the noise (of course sometimes you have a system that pumps in extra energy to counter the noise). with reference to airfoils noise means turbulence and turbulence causes drag. it also may compensate for less surface area by varying the pitch of the blades by a larger margin. im merely saying that it is possible to throw actual engineering at the problem and come up with a solution that does not require gutting the chopper and replacing its entire drive train (which probably would include messing with the engine). if that were the case it may have been cheaper to just build a new type of chopper.
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while possible, I don't think it is likely, they probably told boeing or someone to make 5 of these and they did, it's always easier to make something from scratch than cutting holes and bolting together and stealth tech is finicky about small details, so I doubt they would have started with a built physical helicopter and made it stealthy, though I'm sure it is a relatively minor tweak to the design.
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while possible, I don't think it is likely, they probably told boeing or someone to make 5 of these and they did, it's always easier to make something from scratch than cutting holes and bolting together and stealth tech is finicky about small details, so I doubt they would have started with a built physical helicopter and made it stealthy, though I'm sure it is a relatively minor tweak to the design.
that is nothing the military hasn't done before (huey->cobra). regardless of who's theory is most correct, what is certain is that the details will be classified for a very long time.
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According to AW&ST (http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/05/09/AW_05_09_2011_p22-318890.xml), the crash:
was not a mechanical failure or a problem by the pilot that downed the Black Hawk—it was a miscalculation of temperature in and outside the compound. The Black Hawk ran into lift trouble due to a 15F difference inside the courtyard, says Rep. Buck McKeon (R-Calif.). “They couldn’t hold the hover.”
Cool stuff though. Stealth choppas...
I see a different story every time I look at the paper... :lol: I think settling with power would be quite a possibility, given the structure of the complexes and the altitude the pilots would've had to keep above them. Either way, I'm glad this bloke was versed enough in it not to call it a 'stall'. That gets me every time I look at it elsewhere. :banghead: