[Thaeris]

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!

[jr2]

EDIT:



EDIT2:

[headdie]

there was a bit of a discussion about it here

http://www.hard-light.net/forums/index.php?topic=75896.0

[Thaeris]

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?

[The E]

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.

[General Battuta]

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.

[Thaeris]

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.

[Nuclear1]

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:

[General Battuta]

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:

I just remember one of the elements of the big prison rescue attempt in Nam being smashing a helicopter right down into the compound.

[headdie]

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:

If John McClane was involved there would only be rubble left of the house

[The E]

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.

[Shade]

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.

[Thaeris]

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.

[Thaeris]

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? 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.

[The E]

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.

[Thaeris]

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.

[The E]

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.

[Thaeris]

Well, I suppose that is a decent point. However, I think my point also is valid enough given the circumstances.

[NGTM-1R]

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.

[Nuke]

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.