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Very. *Very*. Interesting.

Anybody who’s ever flown a helicopter in combat is aware of one simple truth: “There’s no way you’re gonna sneak up on anybody in a helicopter.”

Over the years, the boffins have attempted to relegate that truth to the same historical dustbin I now occupy, with varying degrees of success – but never complete success.

It all depended on which aspect of “stealth” they were working on. There are a half-dozen ways of accomplishing IR suppression of the engine exhaust plume to about 20% of its original temp, and the late, somewhat-lamented Comanche had a decent reduction in radar reflectivity of its fuselage. Back in the ‘70s, there was the Invisible Loach, which used rheostats, a wiring harness, and little white Christmas lights to reproduce the ambient light over the fuselage – it worked. I watched the li’l beast hovering at about 50 feet AGL over one of the test ramps. The pilot activated the system (i.e., he flipped the switch) and one each OH-6A vanished from sight. I could still hear it, but even though I *knew* where it was, I couldn’t see it. And sound suppression is a big problem – everything that makes a helicopter fly produces noise. You can play with rotor blade designs and configurations, muffle the engine(s) somewhat, and baffle the structure around the transmission, but you pay a power penalty, either directly, through decreased engine performance, or indirectly through an increase in weight.

It appears the boffins are still looking to give me company in the dustbin.

Look at the pix of the vertical tail – that ain't from any Black Hawk mod I've ever seen, kids. It bears only the most superficial resemblance to the tail and stabilator of a UH-60, and the streamlining has vanished, probably to support the polygonal box at the top, which I’m guessing held one or more additional countermeasures suites in addition to containing the tail rotor gearbox. The round shieldlike affair over the tail rotor hub is an airflow diverter, designed to eliminate the turbulence around the rotor hub, making it more efficient, and probably has a secondary effect of reducing the noise of the tail rotor by making it directional.

The aircraft skin is interesting – it’s perfectly smooth, and I have a nagging hunch it’s something I’ve seen before, back in the late ‘80s. Essentially, it’s a variation on the Invisible Loach – a light-emitting appliqué film which, coupled to directional cameras, will exactly reproduce the light and color patterns on the opposite side of the aircraft. Think of the aircraft as being made of glass, or Predator’s light-bending combat suit, and you’ll get the idea of the effect. Back in the day, the film was too fragile for aircraft applications, but I think they found a way to mylarize it.

The Brits seem to think that the aircraft took an RPG hit and crashed, rather than suffering an “engine stall” as originally reported, or crashing due to the air temperature over the compound miraculously being 17°F higher than that of the surrounding atmosphere, as is the current excuse coming from Foggy Bottom. I might buy off on pilot error, misjudging rate of closure while simultaneously going nose-high to induce settling with power, but that's a rookie mistake, and no one in his right mind would have stuck a rookie in this particular aircraft -- I guarantee you, the pilots flying that aircraft had been flying it for a while, and knew it inside-out.

Look at it this way: If you were DoD or CIA or any of a dozen other Three Letter Organizations and had spent a kazillion bucks over the course of decades on a helicopter touted to have high-tech, gee-whiz, Star Trek all-aspect stealthiness, and it got waxed on its first operational debut by a bad guy who heard it and saw it *at night* and nailed it with a low-tech weapon essentially unchanged for 1,000 years, which story would you push?


If it were shot down, then, it would have to have been at very close range, no?

Also, look at the helo's dead body. It's in a couple distinct places - one of which is a charred heap of ash, while the other is fairly intact. 
Depending on its altitude and airspeed, it could have been 100 meters outside the wall the tailboom is resting on or almost directly over it.

The clump to the left of the pic is what's left of the cockpit, melted to the refueling probe. The gap is where the cabin area used to be, and the large mass to the right is everything else, minus the empennage that wound up inverted against the wall. My guess would be that it hit *hard* with low rotor RPM, and the main rotors flexed down, cutting off the empennage and flinging it against the wall.

One more thing. At least some of the crew and passengers have lower back injuries.
How likely is it that the boom was flung against the wall when the commandos blew up their bird?

IF it was an RPG...

Maybe the gunner just pointed his weapon in a vaguely skyward direction and launched. sometimes, spray and pray gets lucky.
And of course, the bigger the target, the better the odds, Grimmy..........
Stealthing a helo is hard, thanks to, among other things, shape, skin type and a big radar reflector spinning around just above the fuselage. That said, mebbe the skin is somewhat RAM-like (Radar Absorbent Material), some aircraft have been modified to not be so "lumpy" as it were, giving the platform, if not a close-in stealthy capability, at least some semblance of harder-to-see-than-normal during the ingress legs.

Helos are slow enough as it is, so anything that allows you to get just a tad closer before it's obvious you're there (or maybe even while you're on the final IP-to-LZ run) is a Good Thing...and I'm assuming here the approach was designed to fairly tight parameters to maximize some type of direct or indirect masking for surprise). Every little bit helps. So, I wouldn't discount whatever technology that may have been in play here. If the airplane was in fact struck by a projectile, methinks it's being spotted and engaged happened very late in the final approach, where, as you pointed out Bill, hiding engine noise if nothing else is virtually impossible.

In any case, I wouldn't doubt SOCOM, the Army, the Air Force and the Navy have been nugging out how to hide a helo (better). Who knows? They may be close to doing something really mind blowing with them thangs.

What I find fascinating is the other stuff they were using to find, fix and f**k up OBL before and during the op.
How likely is it that the boom was flung against the wall when the commandos blew up their bird?

About the same likelihood of a snowflake remaining intact inside a Bessemer oven.

When you want to destroy secret stuff, you burn it -- explosive charges will likely scatter it, still pretty much intact. That helicopter wasn't blown up, it was burned in place.

Here's my take on this.  It appears that the tailboom and fuselage were on opposite side of the wall.  This would indicate a fairly common occurance.  Your fast and low, you have to flair hard, you miss judge the height of the wall, and blamo no more tail boom.

Bill, is there any info on the Invisible Loach around?  I've done some quick looking, but nothing has turned up...

Aside from that, thanks for the insight and commentary on this bird.  I'd be a bit surprised if it's a completely new airframe, but I could easily see a new rotor/powertrain assembly and tail being built for this kind of mission- only curiosity makes me feel it's sort of too bad they did such a good job of destroying the main portion of the airframe  On the other hand, I hope most of the sensitive parts were destroyed or damaged beyond recognition.
There may be some references in print, but I haven't seen anything on the net -- which isn't odd, because it was a one-ship program. I know the pilot worked for the ARADCOM flight det at Lakehurst, but the lighting harness probably came from CECOM at Ft. Monmouth.
Well, I don't feel so bad about not being able to dig anything up so far, then, but I'll keep looking.  Thanks for the quick reply!
Echo Alpha - the invisible Loach was probably extending the work the Navy did in WWII, when they (after prodding from science-types) discovered that hanging a searchlight under an anti-submarine aircraft made them virtually invisible to U-boats until it was too late - all by causing the luminance in the area of the aircraft to match the sky.
Maybe Son Tay VN type maneuver.
If they'd tried that maneuver --we called it a "whoa, boy" -- and hit the wall with the empennage, the whole area would have been crushed.

If they'd hit the wall with the tail rotor, all the blades would have been bent to Helen Gaughan and the hub and gearbox would have sheared off, not the entire empennage.

The damage and intact area are consistent with only one scenario -- the aircraft hit hard with low rotor RPM, the main rotors flexed down, and one contacted the tailboom just forward of the vertical fin. Which means the the fuselage configuration and rotor blade length are pretty much the same as a normal UH-60.
 Here's an article about another Loach that was designed to tackle the sound problem.

At least one of the ex-Quiet Ones surfaced years later at the Army's Night Vision & Electronic Sensors Directorate in Fort Belvoir, Virginia.

A friend of mine was involved in the first NVG flight testing at Belvoir, and one day I got tagged to fly a Loach-load of spare parts down to him. After the obligatory coffee and conversation, Mike said, "Wanna see something neat?" and led me into the blacked-out hangar. He pulled a canvas curtain to one side and introduced me to the world's quietest helicopter.

I remember being impressed by the tail rotor configuration, but not the cockpit. The FLIR was no longer operational and had been removed, and the fuselage pads had been pulled to save weight -- and aside from the five-bladed main rotor and the scissors-type tail rotor, it was a plain vanilla OH-6.

It sounds like you're trying to confuse these poor people with “common sense”. If I remember correctly, when you compromise sound, you will also compromise lift. Lift is one of those “nice little things that to have around, especially in mountainous terrain”. As to this new bird, I think she will be just another one in a long line searching for this goal. Mama Nature allows some leeway, but definitely not a blank check.
I can always tell when a two-blade-rotor Bell machine is approaching.  The unmistakable "whopwhopwhop"  is audible some time before any of the other noises.  Transonic, and all.  I have read that some of the loudest aircraft ever built were the Curtiss Schneider racers with direct-drive D-12s swinging Reed supersonic propellers.

I remember reading about the lights under airplanes connected to photocells on top, about 40 years ago in the Ga. Tech library.  They had lotsa marvelous books in there; one of the bigger reasons I was never graduated.
Noise wise, how does the NOTAR MD520 compare to the basic OH-6/500 ?
The noisiest part of the OH-6 is the tail rotor -- that's the bumblebee-on-steroids sound that you'll hear long before you hear the engine or the main rotor. The NOTAR is (obviously) a lot quieter -- the fan in the tailboom produces a low-pitched hum, but you have to be fairly close to hear it.
P.s. Back around 1970,  I heard that Bell was working on swept tips for the blades. I think it was more for efficiency than noise.  I wonder what became of that.

P.p.s.  About the same time, a friend and I decided to make a rubber-powered helicopter from drawings in American Modeler.  We couldn't get it to fly stably, so went up the Hill to th library I mentioned above and checked out some books on helicopter aerodynamics. Hey, we'd just had two years of calculus and physics, engineering would be no problem, right?  Wrong.

It is possible to understand and design an airplane from first principles, knowing a very little bit of math and physics.  I've done it myself severeral times, and lost lots of them out of sight over head in thermals.

When we opened up the first of the helicopter books, we were immediately in over our heads.  There were empirical equations, rules of thumb, hand-waving assumptions, head-hurtingly abstruse math about rotating flow fields, non-linear superpositions, huge matrices, you name it.

To this day, I do not think anyone completely understands all of the details about how those gizmos actually work.

P.p.p.s.  I think our problems resulted from trying to use the simpler version of the hub, which locked up under torque unless you bent the little wires just right.
Ain't no such thing as a *simpler* main rotor hub -- there's only "complex" and "excruciatingly complex"...
Yup.  I reckon that's why it didn't work. 
I have ridden in a non-rigid airship. I have ridden in a DC-3.  I have ridden in various jet-propelled airliners, including a Convair 880, my favorite of that ilk. I have ridden in a DC6-B.  and been invited through the always-open door to the flight deck. I have ridden in a Ford Tri-Motor.

  I have ridden in, and flown a bit, m'self, a Piper Aztec,  an Aeronca Champ, and a Grumman Widgeon.  I was allowed to taxi a Cessna 150 between the scary-looking Marines in their green coveralls, and their helicopters, and do the takeoff and fly around for a bit. (The instructor insisted on doing the landing.)

Back when I was younger and dumber, I might have been persuaded to go for a ride in a hellaflopper, just for fun.

I will not do that for fun, the way I feel these days. I will of course happily accept a ride in a hellaflopper if that is the only way to avoid certain death.

If it's just likely death, well, as Jack Benny said, "I'm thinking!"
My comment has been received and held for approval?  All I talked about was flying, and airplanes! ( with some bad remarks about hellafloppers) Thwack those Server Gnomes good and hard with a horsewhip, Sir, if you please!
JTG, probably your PpS and PppS with dots is what caused the hold.
JTG:  Gotta stick with acronyms that even a gunner can understand instead...
Bill T,  Could be right but I'm not ready to consede just yet.  Unfortunately there's probably not enough data to say for sure.  Your scenario doesn't explain why the tail is on the wrong side of the wall?  And if you look at the rest of the burnt out wreck, it's awfully close to the wall on the inside of the compond.  Maybe TOO close for a UH-60.

I remember the quiet "Loach" program.  As you know the OH-6 was very quiet (for a helicopter) to start with.  I got several of my kills by literally catching the VC with their pants down, during "first light" recon's.
 I remember research trying to quiet a Cobra somewhat back in the 70s. The rotor blades I saw the pic of had tapered chords near the tips. I don't know if they tried a 4 blade rotor or not. The problem with the 4 blade rotors is they tend not to have as much inertia and the chopper doesn't allow as much slack in autorotation. The Jet Ranger was not a good autorotater, and the Kiowa "D" uses a 4 blade, low inertia rotor which makes Autorotation even more fun, from what I hear.

Given the position of the tail rotor and the cockpit, I'm more inclined to think they hit the wall accidentally. No op is perfect and it would just be part of the friction and fog you see in such ops. I'm also betting, with Bill, there are a few sore lower backs.
Quartermaster, as someone who has done many practice autos in a jet-ranger, I can tell you that it is an outstanding autorotating aircraft unless you are specifically referring to 4 bladed versions.  I have only flown 2 bladed 206's.   I agree, with your description of the accident,  you get into power settling which is aggravated by trying to arrest forward and downward motion simultaneously and I can easily see you hitting that wall with boom.
Qm, obviously you need to start your grandson researching this question right now!

Of course he won't be interested unless the idea catches his fancy, but then there would be no stopping him. Snork.
JTG - Back in the day, I wrote a series of techno articles for Air Force magazine. Even with my anti-math gene, I figured it out. How a jet engine works? No problem. How to land an airplane? Check. Helicopter mechanics? Um...... no.  
 Sim,  My source is people that have flown the OH-58 A-C models which was pretty much a Jet Ranger. I've heard even bigger complaints about the Kiowa D model. Having never flown one I can't speak first hand, but that's what I've been told by more than one that has.
QM, I believe you are right about those OH-58s, probably much heavier than a straight 206.  Don't even have to go look it up, all that extra gear had to weigh at least 500lbs+
Hey, this is really fun. We can do an endless loop of link-backs. Seriously, though... great score on the Big Peace article!