Those who were worried that China could get its hands on some pieces of the ill-fated chopper that crashed in the Osama Bin Laden compound to reverse-engineer the Stealth helicopter have to accept the unpleasant reality that the Chinese have already copied it. As a matter of fact, on May 23, 2011, Dragon Models (based in Hong Kong, China) announced a new model (to be released in July): the 1/144 scale Stealth Helicopter “Operation Geronimo” (Twin Pack).
Image: Dragon Model Limited
If you look at the artwork on the box, you’ll notice that the one created so quickly by DML is quite similar to the concept I developed with Ugo Crisponi. It has the same (fictional) intakes and exhausts, and the overall shape is almost identical. To be honest it also includes some of the inaccuracies of our famous MH-60X rendering (dated May 5) that we fixed in a subsequent “release” (published on May 17) and a few more (based on the artwork, the blades seem quite unrealistic while the horizontal stabilizers are different from what the pictures suggest).
Anyway, here below you can find the May 5 sketch and if you compare it to the above image, you’ll see that, most probably, I and Ugo had the same ideas about the Stealth Black Hawk as the Dragon graphic designers. Noteworthy, the model comes with the unofficial/unconfirmed raid’s codename, since the official one is Operation Neptune’s Spear and not Operation Geronimo (“Geronimo” was the codeword for Bin Laden’s capture or death).
Above: the Stealth Black Hawk rendering I published on this site on May 5. Below the new version issued today (May 31, 2011).
Here’s an excerpt of how Dragon introduces its new model:
[...] Looking like a mixture of MH-60 Black Hawk and F-117 Stealth Fighter, this mysterious helicopter from the 160th Special Operations Aviation Regiment (SOAR) has distinctive edges and angles. The fuselage, nose and tail were all modified to reduce the craft’s radar cross-section.
[...]Befitting the innovative and ultra-secretive shape of the helicopter, this model is newly tooled in every aspect. All the low-observable features such as the angled surfaces are carefully rendered. [...]
To be or not to be [Stealth]: that is the question
If Drangon dared to venture into a Stealth model about which we still know very little (even if a 1/144 scale is small enough to “hide” some unknown details), Italian model manufacturer Italeri, took a different approach. Instead of producing a small kit of the Stealth Black Hawk basing on few pictures or artworks they announced a larger 1:48 UH-60/MH-60 Black Hawk “Night Raid”. The model box in this case is depicted performing a “generic” Special Forces operation inside a compound in Afghanistan (or Iraq).
Italeri told me that they have decided not to launch a product that, most likely, would have been quite different from the real Stealth Black Hawk, given the few images and known facts available to date. So they released a “normal” Black Hawk even if they are ready to work on a realistic “Silent Hawk” as soon as new details about the modified MH-60 used in the OBL raid will surface.
Whatever the choice (stealth or not stealth), such a quick reaction by both Dragon Models and Italeri shows how fast the response to a news story (and to the subsequent market demand) can be.
Dealing with the daily updates about the OBL raid and the Stealth helicopter, here’s an interesting news: on May 30 some media reported the (unconfirmed) news that two helicopters crossed the border between Afghanistan and Pakistan to take five Taliban members in North Waziristan, and bring them back across the border into Afghanistan. This article provides an interesting analysis of the episode. Obviously, I’m not suggesting Stealth Black Hawks were involved again; however, given that the targets were high-value ones and that this kind of mission (once again in “enemy territory”), if confirmed, would be probably carried out by Special Forces, who knows?
I’ve already written a lot about the Stealth Black Hawk, whose existence is proven by pictures taken at Abbottabad the day after Osama Bin Laden raid, and about a Stealth Chinook theoretically taking part in Operation Neptune’s Spear. However I hadn’t thought about another stealth helicopter possibly flying in Pakistan during the OBL raid until I saw a video of a 160th SOAR rescue mission in Iraq that reminded me that the Night Stalkers often fly mixed formations of Black Hawks and MH-6 Little Birds, smaller choppers conducting, for example, rooftop insertions of Special Forces. The 160th SOAR is equipped with both MH-6s and AH-6s, the attack version of the Little Bird, aircraft that were used in almost all US (special) operations: from Op. Urgent Fury (1983, Grenada) to Just Cause (1989, Panama) to Gothic Serpent (1992, Somalia) to Iraqi Freedom (since 2003) the MH-6s have been a constant presence within some of the most difficult operations involving Delta Force and Navy Seals. In 2009, AH-6s took part in the helicopter assault (involving Navy Seals) to kill wanted terrorist Saleh Ali Saleh Nabha in Baraawe, Somalia, taking off from a US vessel. Having imagined the possible shape of a Stealth Black Hawk and Chinook, why not consider the possibility that even a modified, quieter, stealth MH-6X took part in the OBL raid flying with the 160th SOAR? I know that there’s almost nothing that can give some credence to this theory especially because another Stealth helicopter on the scene would make the air space over Abbottabad too crowded. However, I wanted to give it a try and hear what my readers think about a Stealth Little Bird. So, once again, I’ve asked Ugo Crisponi to help me with a rendering of a fictional “Black” MH-6 (6-bladed main rotor and 4-bladed tail rotor) that could be obtained with some modification of the original Little Bird:
I’ve just said that there is “ALMOST” nothing to give credence to the new theory of a Black fleet made by Stealth Black Hawk, Chinook and Little Bird. In fact, a highly modified “Black” Hughes 500s, was used by the CIA in 1972 from a Laos base. An extremely interesting article published in 2008 by Air & Space recalls the story of two OH-6As which were modified to fly with Air America and “to quietly drop off and pick up agents in enemy territory”. Dubbed “Quiet One”, the somehow stealth helicopters conducted their secret mission, on Dec. 5 and 6, 1972, when they carried in N. Vietnam commandos to place a wiretap and a solar-powered relay station that enabled Americans to eavesdrop communications on a telephone line used by the enemy commanders.
The article, written by James R. Chiles, provides some interesting details about the “Quiet One”:
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 [...]. The helicopter also had extra fuel tanks in the rear passenger compartment, an alcohol-water injection system to boost the Allison engine’s power output for short periods, an engine exhaust muffler, lead-vinyl pads to deaden skin noise, and even a baffle to block noise slipping out the air intake.
The extensive alterations did not blank out all noise, Taylor says. Rather, they damped the kinds of noise that people associate with a helicopter. “Noise is very subjective,” he says. “You can reduce the overall noise signature and an observer will still say, ‘I can hear it as well as before.’ It’s related to the human ability to discriminate different sounds. You don’t hear the lawnmower next door, but a model airplane is easily heard. It has a higher frequency and seems irritating.”
It also explains that some Quite One’s modifications can be found on later choppers:
“The agency got rid of it because they thought they had no more use for it,” says Glerum. At least one of the ex-Quiet Ones surfaced years later at the Army’s Night Vision & Electronic Sensors Directorate in Fort Belvoir, Virginia.
But according to the participants, no more were built. It’s puzzling why the CIA did not keep a stable of Quiet Ones, at least while the technology remained under wraps. And it remained a secret for more than two decades, until Ken Conboy and James Morrison told the story in their 1995 book Shadow War.
But there were valid reasons for dropping the Quiet One from the spymasters’ catalog.
“In the long run, the 500P was not the best for setting wiretaps,” says Casterlin. “It was not good for high-altitude work.” It was a light helicopter and had to be loaded with gear that cut into its payload capability and operating altitude. The Twin Pack was much louder but also simpler to run and more powerful, so Air America used it for later wiretap missions in North Vietnam. At least one tap, placed on the night of March 12-13, 1973, was successful.
Some of the Quiet One’s innovations did show up on later helicopters, including the Hughes AH-64 Apache, which has a scissor-style tail rotor. And Hughes engineers’ interest in modifying the tips of the main rotor blades to cut the slapping noise caused by blade vortices has been taken up by other experts. Aerospace engineer Gordon Leishman and his team at the University of Maryland, for example, are developing a blade with curved tubes at the tip to divert the air, thereby countering vortex formation. But, thanks to its many unusual modifications, the 500P still holds the title that Hughes gave it in April 1971: “the world’s quietest helicopter.”
Take a look at the following screenshots taken from a Youtube video taken with a helmet-mounted camera by US Special Forces (Delta Force’s A Sqn) rescuing Italian and Polish contractors from a hideout in Iraq with the help, once again of the 160th SOAR, on Jun. 8, 2004.
The first thing I thought when I saw the footage is that sometimes history repeats itself.
Here the full video. The impact is clearly visible at mins 1.23 and 1.49:
Contractors had been abducted in Baghdad on Apr. 13, 2004 along with another Italian citizen, Fabrizio Quattrocchi, who was killed by kidnappers on Apr. 14.
A daring rescue operation was put into action as soon as coalition forces gathered reliable information on the location where the hostages were being held. As the footage shows, the 4 MH-60s (using c/s “Prince 61 – 64″) along with 4 escorting AH-6s (“Granite 71 – 74″) flew over Baghdad then approached fast and low the compound where the workers were held.
While the third MH-60K (“Prince 63″) was flaring before touch down (with a dust cloud raised by the preceeding choppers) it hit the comp0und’s wall with its tail rotor beam/stabilizer. Fortunately, unlike what happened in Afghanistan during Operation Neptune’s Spear, the Black Hawk did not break apart and it was able to land allowing the SOF operators to leap out and to rescue hostages. The operation was successful (as the OBL raid was) and the helicopter was (probably) able to return to its base (the video doesn’t show this phase so we can’t be completely sure it didn’t suffer some structural damage).
Anyway, what happened during the 2004 rescue in daylight conditions, seems like a confirmation to what I’ve already suggested yesterday (pt1) describing the possible root causes of the crash landing of the Stealth Black Hawk during the OBL raid: the helicopter might have hit the compound’s wall on fast approach for landing at night with NVG in a particularly long and exhausting mission. A lesson to be learned for future special ops involving low level approaches to compounds surrounded by walls?
An interesting article published yesterday by the Associated Press and commented by Wired/Danger Room, provided some interesting details about the Osama Bin Laden raid. Indeed, anonymous government sources have told the story to the AP even if information they disclosed, raise more questions…
Anyway, first of all, I can’t help but notice that my possible explaination of Operation Neptune’s Spear (OBL raid’s name), published on May 6, was not disproved by facts disclosed so far!
Five aircraft flew from Jalalabad, Afghanistan, with three school-bus-size Chinook helicopters landing in a deserted area roughly two-thirds of the way to bin Laden’s compound in the Pakistani city of Abbottabad, two of the officials explained.
Good. The departure aerodrome is Jalalabad (my guess was right) and there were also 3 Chinooks. Let’s have a look to what I wrote on May 6:
“I think there are two possibilities: both [helicopters involved in the raid] were Silent/Stealth/Upgraded/Modified/etc. Black Hawks; or 2 were Stealth Black Hawks and Stealth Chinooks. I don’t believe that “normal” MH-47s were involved as some media speculated (for the above mentioned considerations on the stealthiness of the formation) so, I’m almost sure only new Black Hawks were used. However, since we now know that a Black Helicopter exists, I can’t completely rule out the possibility that, along with a Stealth Black Hawk, somewhere there’s also some sort of modified Stealth Chinook flying“.
Since the officials confirmed that 3 Chinooks were involved and given that a mixed formation of stealth and non-stealth helos would have rendered the entire formation clearly visible on radars and audible from distance, I believe that there must be also a modified MH-47 flying with the 160 SOAR. Unlike the Black Hawk, we have no photographic evidences of it, but I think that their existence is somehow confirmed by the fact that the officers admitted their presence on the scene. Furthermore, it is quite obvious that the sources are trying to deceive the public opinion when they say to the AP journalist that:
The Black Hawks were specially engineered to muffle the tail rotor and engine sound, two officials said.
You can’t reduce noise by modifying only the tail rotor. Even the main rotor had to be fixed. And what about the anti-radar finish to enhance stealthiness? In my opinion, as explained in the last post on this subject, the Stealth Black Hawk is a highly modified version of the UH-60 helicopter.
I’ve asked once again to Ugo Crisponi to prepare a sketch of how a Stealth Chinook might look like by applying more or less the same modification used for the Stealth Black Hawk.
The same AP article then gives some details about the Stealth’s crash landing:
The added weight of the stealth technology meant cargo was calculated to the ounce, with weather factored in. The night of the mission, it was hotter than expected. [...]
The plan unraveled as the first helicopter tried to hover over the compound. The Black Hawk skittered around uncontrollably in the heat-thinned air, forcing the pilot to land. As he did, the tail and rotor got caught on one of the compound’s 12-foot walls.
On this topic I had a chat with a friend of mine, who’s a former helicopter combat pilot with some Tour of Duty in Afghanistan. He’s quite skeptical about the “weather factor”: Abbottabad is “only” 4.000ft AMSL and at night, the temperature is always (well) below 30° C. Even a heavy modified helicopter should not have problem hovering over the compound. Hence, there could have been three kind of “root cause” for the crash landing:
1) flying a very risky mission at night with Night Vision Goggles, the pilots could have lost situational awareness and impacted the compound’s wall while approaching it for landing. This would explain why the tail is cut as images show
2) the helicopter, flying at lower altitude than the other Stealth Black Hawk, was hit by wake turbulence generated by the other chopper’s rotor. “It’s a very dangerous situation” my friend told me “since the turbulence hits both the main and tail rotor, giving almost no chances to react”
3) there was a “recirculation condition”: exacerbated by proximity to walls or cliffs or trees, this occurs when the air passes down through the rotor disc, hits the ground, moves out horizontally, hits the wall, goes up and then gets sucked down again through the rotor. You then have air that is already moving down coming through the disc and this leads to a greater power requirement which can then make the effect worse. This accident may not have been helped by the modifications to the tail rotor to make it stealthy that also reduced its efficiency and need for more power. It may not have been helped by pilot’s under pressure,
coming in low and fast, possibly with obscured vision behind the first aircraft throwing up dust/sand.
This is how the Stealth Black Hawk (dubbed also “Silent Hawk”) could look like based on the analysis of all the information available to date. It is sensibly different from the previous sketch; if you read below you’ll understand why.
After publishing the various famous sketches of the possible shape of the modified Black Hawk (dubbed “Stealth Black Hawk” or “Silent Hawk”), together with Ugo Crisponi I’ve continued studying pictures, suggestions, comments and all the information available about the mysterious helicopter that performed a crash landing during the Osama Bin Laden raid. While some hundred thousands readers all around the world, along with major media worlwide, much appreciated our work, others argued that we were giving bad guys some valuable information about a “black project”. Actually, the sketches were based on my initial analysis of the publicly available pictures, that Ugo was able, through a series of attempts, to “translate” into a realistic shape. So, what we did could be done by anybody willing to spend some time studying images and thinking to all the possible modification that could make a Black Hawk, if not stealth, more silent.
Furthermore, a far more in-depth study that could be used to project a Low Observability UH-60 is already in the Public Domain and freely available on an official US military website. It was issued in 1978 by Sikorsky Aircraft Division for the US Army Research and Technology Laboratories and it is titled: “STRUCTURAL CONCEPTS AND AERODYNAMIC ANALYSIS FOR LOW RADAR CROSS SECTION (LRCS) FUSELAGE CONFIGURATIONS”. It shows that first attempts to give the UH-60 some stealth capabilities dates back to 33 years ago. Although I can’t expect the fuselage concepts for low radar cross section aircraft configurations designed at the end of the ’70s still apply today, the basic concept around them could be still useful to imagine a few modifications to the Stealth Black Hawk profile as I initially thought it.
Noteworthy, the shape suggested in 1978 document reminds that of an F-117 rather than that of a more modern stealth, like an F-22. This is consistent with the article published on Army Times titled “Mission helo was secret stealth Black Hawk” according to which the helo has “hard edges, sort of like an … F-117, you know how they have those distinctive edges and angles — that’s what they had on this one”.
Here below, you can read some excerpts of the above mentioned public document that I used with Ugo Crisponi of Aviation Graphic to review the sketch.
Three fuselage configurations for low radar cross sections were developed by the Applied Technology Laboratory. [...] The main rotor pylon fairings and tail surfaces aft of a tail fold hinge for each configuration were the same as those for the baseline UH60A. In the initial portion of this study, the weight and costs (percent of total) were developed for sections of the baseline UH60A fuselage. [...] Structural concepts were developed which could be applied to each configuration using conventional materials. An assessment of safety, fail-safety, and maintainability for each configuration was performed. The change in structural weight and the percentage change in cost for each configuration using the concepts developed were compared to those of the baseline. One concept was selected and applied to the three configurations.
Having selected the structural concept with the lowest weight change and percentage cost change for the three fuselage configurations, the effect on weight and costs using advanced materials was developed and applied to the three configurations. To evaluate the impact of the results of the fuselage study, design attributes of six helicopters were developed using a Helicopter Design Model (HDM) computer program.
Three low radar cross section fuselage configurations for this study were developed by the Applied Technology Laboratory. The first configuration slightly modified the nose section from the baseline configuration; the second configuration changed the fuselage shape along the lines of a truncated triangular prism; the third extended canted flat side shaping throughout the fuselage. The tail surfaces and main rotor pylon fairing were the same as those of the baseline UH60A.
This configuration alters the baseline fuselage forward of the mid-cabin section (the cockpit). Although this configuration is different from the baseline, the internal structure must be compatible with the forward cabin to avoid a heavy joining structure. The overall length is slightly increased due to this configuration.
This configuration is basically a trapezoidal cross section airframe having sides canted inward 30° and made up of flat exterior structural panels. This configuration is wider at the bottom of the fuselage and narrower at the top of the fuselage than the baseline. This configuration is slightly longer than the baseline UH60A, and its overall height is slightly larger than the baseline. The increased length, width, and height of Configuration 2 does not allow an aircraft of this size to meet the air transportability requirements of the baseline. The narrow upper fuselage causes the pilot and copilot seats to be spaced closer to each other, and shoulder room in the main cabin is decreased. The main cabin floor is approximately 6 inches higher than the baseline from the ground. The increased floor-to-ground height causes difficulties for combat troops to enter or leave the aircraft quickly. Minor modifications of the mold lines for the transition and tail-cone sections were made to properly house the tail rotor shaft of the baseline UH60A.
This configuration is basically a flat side cross section airframe having sides canted inward 50 and is tapered in width from a narrow cockpit section to a transition section as wide as the baseline UH60A. The tail-cone is a rectangular section which is narrower than the baseline. The narrow cockpit causes the pilot and copilot seats to be spaced closer to each other; space for four-across seating in the main cabin is decreased. The cockpit and main cabin floors are at the same height from the ground as the baseline. The slope of the windshields may cause problems of visibility for the flight crew. Minor modifications of the mold lines for the transition and tail-cone sections were made to properly house the tail rotor shaft of the baseline UH60A.
ADVANCED MATERIAL APPLICATION
Advanced composite materials can be used in the construction of the three fuselage shapes considered in this study. Studies, have shown that the use of composite materials can reduce both fuselage weight and cost. The fuselages of this study are relatively lightly loaded compared to fixed-wing aircraft. To efficiently use advanced materials in the fuselages, very light composite skins are used in the post-buckled stress state. [...]
Structural concepts developed for the three LECS configurations showed that extensive reshaping, as exemplified by Configuration 2, would increase fuselage weight from that of the baseline UH-60A fuselage by 223 pounds and cost by 3.65 percent. When advanced materials were used Configuration 2 decreased
from the baseline fuselage weight and cost by 116 pounds and 3.98 percent respectivdly. Total aircraft performance capability was degraded primarily by drag effects. The aerodynamic analysis indicated that Configuration 2 would have a vertic climb rate at 15 percent of the baseline. Weight, cost, and performance penalties were less in Configurations 3 and 1 respectively.
Based on the results of this study, the following conclusions are made:
1. The use of advanced materials can result in both weight and cost savings over the baseline fuselage, even with the most severe change in LRCS configurations presented.
2. Without the use of advanced materials, the LRCS Configurations 2 and 3 significantly increase both weight and cost of the total aircraft compared to the baseline UH60A.
3. Minor changes to the nose section of Configuration 1 result in negligible fuselage difference to the weight and cost of the fuselage.
4. Consideration of the total aircraft attributes show that vertical drag penalties appear to be of greater magnitude than the structural weight changes involved with the fuselages of Configurations 2 and 3.
Even with the use of advanced materials, the vertical drag penalty exceeds any weight savings.
The sketch was revised to take the document into consideration (without forgetting it was issued at the end of the ’70s). Even the main rotor was redesigned to make its head slightly larger (with a noise reduction cover sheltering the motion-control technology used to input low-frequency variations of rotor blade pitch-angle, as tested by NASA) .
One last thing worth a mention.
In the aftermath of the crash landing, on May 5, Jon Nowinski, an investigative reporter and founder of the Smoking Gun Research Agency (www.sgra.org) sent me an email to let me know that:
[... ] over the last few days there has been an increased number of late-night helicopter flights to the Sikorsky plant. While that doesn’t entirely stand out as odd, it is interesting to note that normally these flights are related to testing aircraft, as well as consistant with what happens when a Sikorsky helo goes down in military action. After an accident like that, military investigators and officials frequently come out to the Sikorsky plan for a debriefing during which they review the operation
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