An interesting combat chopper profile officially cleared for publication: MH-60S Armed Helo On May 3, 2011, in the aftermath of the Osama Bin Laden raid that disclosed the existence of a stealth helicopter based on the UH-60 Black Hawk, Ive started thinking about the secret chopper used to carry the Navy SEALs to Abbottabad. Which noise reduction technologies does the chopper embed? Which upgrades render it radar-evading? The answer to these questions can be found in the digital mock up of the Stealth Black Hawk that has become so widely known in books, documentaries and videogames to be considered almost official rather than fictional. Unfortunately, even if since May Ive received hundred alternative sketches and comments about the stealth helicopter (known also as Silent Hawk or MH-X, with the latter being a fake designation) and Ive also learned of a low cost stealth retrofit for obsolete choppers, Ive never had any evidence that the shape that Ive hypothesized with Ugo Crisponi is really anywhere near the actual one. Hence, Im particularly glad to publish a rendering of an existing somehow rare weapon system based on the MH-60S helicopter, designated Armed Helo (and not Knighthawk or Seahawk as sometimes referred to), officially cleared for publication by the U.S. Navy. Therefore an exact copy of the MH-60S BuNo.167818 armed with 8 AGM-114 Hellfire missiles, 2 cal. 50 and 2 FN machine guns.

The Armed Helo Mission Kit, provides the base MH-60S with the capability to extend the HH-60H Seahawks typical Combat Search and Rescue/Personnel Recovery (CSAR/PR) role with Special Warfare Support (SOF), Maritime Interdiction Operations (MIO), Intelligence, Surveillance and Reconnaissance Operations (ISR), and Anti-Surface Warfare (ASUW) missions. The one depicted in the rendering is dubbed Dark Knight and belongs to the HSC-22 a squadron providing helicopter detachments for Littoral Combat Ships, Amphibious Ready Groups and Combat Logistic Ships, and able to perform wide variety of missions: Naval Special Warfare, Amphibious Search and Rescue, Theater Security Cooperation, Strike Coordination and Reconnaissance, Anti-Surface Warfare, Humanitarian Assistance and Disaster Relief and Utility missions in support of the Fleet and National Defense.

Updated: Mysterious Stealth Helicopter photographed in California is a retrofitted obsolete chopper turned into gunship Helikopter Hysterie blogs editor Axel M. Vollmer, who posted my Stealth Black Hawk digital mock up in May, has recently taken the following pictures of amysterious Stealth Helicopter sitting out in the open at Torrance Airport / Zamperini field, home of Robinson Helicopters, in California.

Although Alex wonders whether he has stumbled upon a next-gen US military helicopter or has just seen a new experimental chopper, he admits that the black helo parked at Torrance airport must be some kind of fake stealth used for a movie. Obviously, I dont think the above chopper has anything in common with the Stealth Black Hawk involved in the Osama Bin Laden raid either. It hasnt anything youd expect in a real stealthy chopper: rotor shape, type of blades, noise reduction covers, etc. (without considering that unrealistic AIM-9L Sidewinder carried on the right wing.). Furthermore, not even it would be sitting without armed guards in case of an emergency landing. However Id be curious to know if anybody know something more about this helicopter or is able to understand which basic model was so heavily modified and for what purpose (movie, documentary, TV drama series, ). Update: thanks to Thorsten, a visitor of this site, Ive discovered that the above aircraft is a derivative of the American Aircraft Penetrator, a proposed gunship conversion of the famous Bell UH-1 Huey, whose name is Stealth Star. According to the official website the Stealth Star is the result of a retrofit of an existing helicopter performed by AEROCRAFT Corp under AEROCRAFT Strategic Advantage Program (ASAP).

AEROCRAFT mission seems to be addressed to government agencies rather than private owners: Countries must now defend themselves against the growing threats of small-scale conflicts. These elusive threats, from terrorism to border incursion, drug wars and insurgency, have forced the defense to take the high ground. And the best weapons for this new battlefield is specialized, highly advanced helicopters, designed to penetrate the new combat arena and withstand small arms fire. Many government agencies cannot compete effectively in this new combat arena because their Vietnam-vintage helicopters are too old. These helicopters share obsolescence, redundancy, and poor aerodynamics, ballistics vulnerability and often carry outmoded weaponry. Aluminum exteriors and blind spots make them vulnerable to small arms attack. The high heat signature from the helicopters turbo shaft is an easy target for heat seeking ground missiles. History has shown that 90% of helicopters were downed by small arms fire and 80% of these never saw their attacker. The cost of purchasing new, advanced helicopter systems is astronomical. And the process can take years of negotiation. AEROCRAFT can help you eliminate these obstacles. [...] Through ASAP, an existing helicopter can be reconfigured into a powerful Penetrator gunship within 18 months. This is a significantly shorter time frame than the three to fiveyear schedule required purchasing a new helicopter. And, depending on the options required, up to three Penetrator gun ships could be purchased for the cost of one new helicopter.

Dealing with the tech embedded in this alleged stealth chopper: A KEVLAR all-composite monococque exterior provides ten times the ballistic resiliency of aluminum. The high-visibility cockpit design improves peripheral sight and eliminates blind spots. A heat-suppressing device on the turbo shaft brings the heat signature below the threshold of heat-seeking missiles. The engine is isolated for increased survivability. Fifty caliber machine guns are stored inside. And, new sophisticated aerodynamics are unmatched by any other Western helicopter. So, provided that you trust AEROCRAFT Corp. and their ability to modify an helicopter without affecting its airworthiness and flight safety, maybe you can turn your chopper into a real () gunship.

Stealth Helicopters MH-X designation comes from a temporary filename on this computer Although its hard to believe, Im almost sure that the Stealth Black Hawk that crashed during the Osama Bin Laden raid has never been officially or unofficially named MH-X. Still, if you google MH-X youll find thousands articles that give it as the designation of the Stealth chopper project. Even the prestiogious has a page dedicated to the MH-X: So, hows this weird designation become so widely known? Simple: it was derived from the file name I and Ugo gave to very first version of the rendering of the Black Helicopter. We named it MH-X because we thought it was an upgraded MH-60 but since we didnt know which could be the exact designation we used the X meaning a mysterious number. So all the files with the renderings of the helicopter that Ive uploaded to this website were all named mh-x.jpg or mhx-2B.jpg or mhx-2011 (sometimes with numbers used to identify the different revision: for example mh-x3.jpg, mh-x4.jpg, mh-x4 new2, etc.). Noteworthy, even for the artwork prepared for website we used the designation MH-X even if it was clearly fictional!

By the way, the last one is named MH-X-2011_I and, unlike the F-35I, the I suffix doesnt identify any special version developed for Israel. Hence, unless some of my readers will be able to prove that the MH-X project existed before we used it (in fact, I cant completely rule out the possibility that we used the correct designation by accident) Im becoming increasingly convinced I should write it MH-X :)

In the meanwhile, since you may be interested, heres the story of the MH-X concept since the beginning.

Pakistan let China examine Stealth Black Hawk helicopter: so what? On Aug. 14, the Financial Times and the NYT, followed by other media all around the world, published the news that in the days after Operation Neptunes Spear Pakistans intelligence gave China the opportunity to examine the remains of the Stealth Black Hawk that crash landed during the raid that killed Osama bin Laden.

Is this really a front page news? In my opinion, it is not, as it was quite predictable. We have already seen videos and pictures of chunks of the top secret radar-evading helicopter, being moved from the Bin Ladens compound at Abbottabad. Not only the tail rotor section, that had remained almost intact and whose shape indicated that the one involved in the incident was not a common MH-60, but even smaller parts, like the one collected by Adam Roberts of the Economist on May 3, 2011, that had also a Part Number on it.

Furthermore, China is Pakistans main military equipment supplier and ties among both nations are extremely tough and, to let things even simpler, Islamabad has never accepted that the US carried out the raid without Pakistans prior approval. Thats why, ironically, on May 31 I wrote a blog post titled China has already reverseengineered the Stealth Black Hawk. Hence, it was quite obvious that Chinese would soon be able to have parts of the Stealth technology used to make a Silent Black Hawk. How long does it take for China to have its chopper capable to elude radar? Not so much. Most probably, one or two years, considering the number of Stealth fighters being developed by Beijing and the ability of Chinese engineers to copy classified Western technologies. However, a big help could come also from the US. An interesting freely available document, issued in 1978 by Sikorsky Aircraft Division for the US Army Research and Technology Laboratories and titled STRUCTURAL CONCEPTS AND AERODYNAMIC ANALYSIS

FOR LOW RADAR CROSS SECTION (LRCS) FUSELAGE CONFIGURATIONS shows the first attempts to give the UH-60 some stealth capabilities. Stealth Black Hawk crash landing in Abbottabad could be (alarmingly) similar to a tail strike episode occurred to 160th SOAR in Iraq Take a look at the following screenshots taken from a Youtube video taken with a helmetmounted camera by US Special Forces (Delta Forces 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 comp0unds wall with its tail rotor beam/stabilizer. Fortunately, unlike what happened in Afghanistan during Operation Neptunes 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 doesnt show this phase so we cant be completely sure it didnt suffer some structural damage). Anyway, what happened during the 2004 rescue in daylight conditions, seems like a confirmation to what Ive 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 compounds 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?

Although they cant be considered as a handbook for Stealth choppers, the fuselage concepts for low radar cross section aircraft configurations designed at the end of the 70s still apply today and the concepts behind them could be still useful to imagine the real shape of the Stealth Black Hawk. Thats why Ive used them to create the famous Stealth Black Hawk concept that will appears in todays newspapers until the real modified Silent Hawk will be disclosed or until China will announce its first Stealth chopper.

Introducing the Stealth Little Bird (based on a true story about the silent black OH-6 used during the Vietnam War) Ive 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 Neptunes Spear. However I hadnt 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 MH6s 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 theres 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, Ive asked Ugo Crisponi to help me with a rendering of a fictional Black MH-6 (6-bladed main rotor and 4bladed tail rotor) that could be obtained with some modification of the original Little Bird:

Ive 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 Ones 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 engines 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. Its related to the human ability to discriminate different sounds. You dont 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 Ones 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 Armys Night Vision & Electronic Sensors Directorate in Fort Belvoir, Virginia. But according to the participants, no more were built. Its 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 Ones 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 worlds quietest helicopter. The Stealth Chinook involved in the Osama Bin Laden raid and why the Stealth Black Hawk crashed in Abbottabad 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 cant help but notice that my possible explaination ofOperation Neptunes Spear (OBL raids 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 Ladens 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. Lets 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 dont believe that normal MH-47s were involved as some media speculated (for the above mentioned considerations on the stealthiness of the formation) so, Im almost sure only new Black Hawks were used. However, since we now know that a Black Helicopter exists, I cant completely rule out the possibility that, along with a Stealth Black Hawk, somewhere theres 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 cant 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 UH60 helicopter. Ive 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 Stealths 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 compounds 12-foot walls. On this topic I had a chat with a friend of mine, whos a former helicopter combat pilot with some Tour of Duty in Afghanistan. Hes 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 compounds 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 choppers rotor. Its 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 pilots under pressure, coming in low and fast, possibly with obscured vision behind the first aircraft throwing up dust/sand. Stealth Black Hawk updated rendering: 1978 document suggests a different shape for the modified UH-60 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 youll 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 Ive 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 cant 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 thats 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, failsafety, 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. CONFIGURATION 1 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.

CONFIGURATION 2 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-toground 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.

CONFIGURATION 3 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. [...] CONCLUSIONS 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 respectively. Total aircraft performance capability was degraded primarily by drag effects. The aerodynamic analysis indicated that Configuration 2 would have a vertical 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 ( 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 doesnt entirely stand out as odd, it is interesting to note that normally these flights are related to testing aircraft, as well as consistent 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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