Download or read book Structural Design Analysis of the Tail Landing Gear Bay and the Vertical Horizontal Stabilizers of the RAH 66 Comanche Helicopter written by Brian Shoop and published by . This book was released on 1997-09-01 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: The RAH-66 Comanche's stealth design requires the use of radar- absorbing material (RAM) on the outer skin of the aircraft. The reduced stiffness properties of RAM produce insufficient tail torsional stiffness, necessitating the use of non-radar-absorbing graphite on the outer skin of the tail section. This thesis investigates structural design modifications to increase the tail section's stiffness to allow the use of RAM on the outer skin and still meet all structural requirements. An original model represents the prototype aircraft at first flight. The goal is to create a model using RAM on the outer skin that watches the structural stiffness of the original model. This thesis builds on earlier work conducted at the Naval Postgraduate School (NPS). Two new design modifications to the tailbone are developed. The best modification increases the torsional stiffness of a baseline model by six percent. Integrating earlier NPS modifications increases torsional stiffness by 12 percent. When RAM is applied to the outer skin of the modified model, torsional stiffness is reduced by only six percent from the baseline as compared to a 24 percent reduction with no modifications. Additional modifications to the vertical and horizontal stabilizers further increase structural stiffness and reduce weight.
Download or read book Structural Design Analysis of the Tail Landing Gear Bay and the Vertical written by Brian P. Shoop and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The RAH-66 Comanche's stealth design requires the use of radar- absorbing material (RAM) on the outer skin of the aircraft. The reduced stiffness properties of RAM produce insufficient tail torsional stiffness, necessitating the use of non-radar-absorbing graphite on the outer skin of the tail section. This thesis investigates structural design modifications to increase the tail section's stiffness to allow the use of RAM on the outer skin and still meet all structural requirements. An original model represents the prototype aircraft at first flight. The goal is to create a model using RAM on the outer skin that watches the structural stiffness of the original model. This thesis builds on earlier work conducted at the Naval Postgraduate School (NPS). Two new design modifications to the tailbone are developed. The best modification increases the torsional stiffness of a baseline model by six percent. Integrating earlier NPS modifications increases torsional stiffness by 12 percent. When RAM is applied to the outer skin of the modified model, torsional stiffness is reduced by only six percent from the baseline as compared to a 24 percent reduction with no modifications. Additional modifications to the vertical and horizontal stabilizers further increase structural stiffness and reduce weight.
Download or read book Analysis of Potential Structural Design Modifications for the Tail Section of the RAH 66 Comanche Helicopter written by Vincent M. Tobin and published by . This book was released on 1997-06-01 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Army RAH-66 Comanche Helicopter made its first flight in January of 1996. Its current structural configuration, however does not meet the Army's requirements for radar signature. Structural configurations of the tailcone that meet radar cross-section requirements tend to lack sufficient structural stiffness due to the presence of Kevlar in place of graphite on the outer mold line. This thesis investigates potential structural design modifications to the Comanche tailcone that would move the design closer to meeting both its structural and radar signature requirements. Geometry modifications with baseline (current configuration) materials increased torsional stiffness by nine percent. Structural geometry modifications using radar signature compliant materials reduced torsional stiffness by 10 percent. The geometry changes analyzed produce structural performance improvements insufficient to allow the use of radar-compliant materials without further geometry changes.
Download or read book Analysis of Potential Structural Design Modifications for the Tail Section of the RAH 66 Comanche Helicopter written by Vincent M. Tobin and published by . This book was released on 1997-06-01 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Army RAH-66 Camanche Helicopter made its first flight in January of 1996. Its current structural configuration, however, does not meet the Army's requirements for radar signature. Structural configurations of the tailcone that meet radar cross-section requirements tend to lack sufficient structural stiffness due to the presence of Kevlar in place of graphite on the outer mold line. This thesis investigates potential structural design modifications to the Comanche tailcone that would move the design closer to meeting both its structural and radar signature requirements. Structural geometry modifications with baseline (current configuration) materials increased torsional stiffness by nine percent. Geometry modifications using radar signature-compliant materials reduced torsional stiffness by 10 percent. The geometry changes analyzed produce structural performance improvements insufficient to allow the use of radar- compliant materials without further geometry changes.
Download or read book Identification of Random Loads Impinging on the RAH 66 Comanche Helicopter Empennage Using Spectral Analysis written by Patrick H. Mason and published by . This book was released on 1998-06-01 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Army RAH-66 Comanche Helicopter is currently undergoing developmental flight testing. The empennage of the aircraft is experiencing buffeting where the horizontal and vertical tail vibrate at resonant frequencies. These high buffet loads are manifested in higher than anticipated fitting loads, particularly on the tail, and vibrations in the crew stations and at the nose cone where the targeting sensors are located. Significant effort has been devoted to identifying the sources of excitation and the nature of the structural response. This thesis determines the location and magnitude of empennage vibratory airloads. Because the nature of the excitation is a random function, spectral analysis is used. To obtain the loads, a three step process was utilized. First, from aircraft differential pressure transducers and accelerometers, the spectral content of the response and excitation was determined. Then, using a NASTRAN model modified to replicate the flight test aircraft, frequency response functions were determined between selected points on the aircraft's tail and the accelerometers. Finally, using this information, a solution was obtained for the vibratory airloads. Having provided information on the nature of the driving forces, structural modifications can be made that move the natural frequencies away from the frequencies of the applied airloads.
Download or read book Success Stories written by and published by . This book was released on 2001 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Finite Element Modeling of the RAH 66 Comanche Helicopter Tailcone Section Using Patran and Dytran written by Mark S. Gorak and published by . This book was released on 2001-06 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The United States Army contracted Boeing-Sikorsky to develop the RAH- 66 Comanche, a new, armed reconnaissance helicopter that features stealth technology designed to improve survivability when operating in hostile environments. Ballistic testing is required on any new technology, to include the Comanche, prior to fielding. Computer based simulations are being employed to reduce the requirements for expensive live fire testing. This thesis uses computer programs called PATRAN and DYTRAN from MSC Software Corporation to build the model and simulate the effects of an explosive round detonating in the Comanche tailcone section. This thesis describes in great detail the process of creating and modifying the model in PATRAN to most accurately depict the Comanche tailcone section and creating the input decks for DYTRAN to run the analysis. A test case involving an explosion with a high amount of explosive energy, or specific internal energy (SIE) was simulated. From this test, several results are shown to display the capabilities of DYTRAN. These results, when compared with live fire data, can be used to validate the computer-based simulation in order to reduce the requirements of expensive live fire testing.
Download or read book The RAH 66 Comanche Helicopter written by Arthur W. Linden and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "On December 5, 2003, Lt. Gen Richard A. Cody, Army Deputy Chief of Staff and an experienced aviator, flew the Comanche. According to the January 2004 issue of National Defense he "...gave the aircraft a stellar review. ...Cody said that the Comanche had 'exceeded his expectations' and was particularly impressed by the rotor system, engine response and control. Cody also reportedly said the aircraft was 'easy to fly' and should be put into the hands of soldiers as soon as possible." Twelve weeks later the program was cancelled. So, what happened? How did Comanche become expendable? How did a program that was originally scheduled to enter Low Rate Initial Production in 1996 get delayed to 2011? How did an aircraft originally designed to replace the Army's light scout/attack fleet grow to become a virtual replacement for the much larger, heavier AH-64 Apache? This is a story of great accomplishment and much frustration. This is the Comanche history, as told by the some of the key members of the Comanche development team"--
Download or read book A Case History of the United States Army RAH 66 Comanche Helicopter written by Jason L. Galindo and published by . This book was released on 2000-03-01 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: The RAH-66 Comanche Helicopter was initiated as the Light Helicopter Family (LHX) in 1982 when an Army Aviation Mission Area Analysis (AAMAA) identified the need for an armed reconnaissance aircraft. Eighteen years later, the program has yet to reach a Defense Acquisition Board Milestone II review. This thesis described the history of the RAH-66 Comanche Helicopter acquisition program during these ears. The research focused on the question of what significant events and issues have occurred over the course of the Comanche's development that have allowed it to remain a viable program. The research draws several conclusions from the analysis of the Comanche's history. Mainly, despite the significant duration of the program, a valid need for an armed reconnaissance platform still exists. Secondly, the innovative program management of Comanche has maintained a positive reputation for the program. Finally, the loss of Comanche at this point in time would severely impact the defense helicopter industrial base.
Download or read book An Analysis of the Impact of Reliability and Maintainability on the Operating and Support O S Costs and Operational Availability AO of the RAH 66 Comanche Helicopter written by Gregg M. Dellert and published by . This book was released on 2001-12-01 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The RAH-66 Comanche helicopter program was initiated in 1983 to develop a reliable and maintainable attack/reconnaissance aircraft to replace the aging feet of AH-1 Cobra and OH-58 A/C helicopters. After several funding reductions and restructurings, the program entered the Engineering and Manufacturing Development (EMD) stage of the acquisition process in 2000. With only four years remaining until initial fielding, the program office is still attempting to reach the ambitious reliability and maintainability goals needed to experience reduced operating and support (O&S) costs and high operational availability (Ao). This thesis analyzes the impact of reliability and maintainability on the O&S costs and Ao of the Comanche helicopter. The research focused on the question of where the Comanche program office should allocate resources to minimize O&S costs and maximize Ao. The research indicated that the best allocation of resources is to the improvement of system reliability. The negative impact to both O&S costs and Ao is significant if the predicted reliability goals are not met.
Download or read book Computerized Ballistic Modeling of the Comanche Tailfan Shroud written by Allen H. Stephan and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The U.S. Army has contracted Boeing-Sikorsky to develop the RAH-66 Comanche, a new, armed reconnaissance helicopter that features stealth technology designed to improve survivability when operating in hostile environments. Ballistic testing is required on the Comanche prior to fielding. Computer based simulations are being employed in order to reduce requirements for expensive live-fire testing. This thesis uses a computer program called Dytran from MacNeal-Schwendler to simulate the effects of an explosive round detonating in the Comanche tailfan shroud. Six test cases involving explosions with varying amounts of explosive energy, or specific internal energy, are evaluated. From these tests, a curve showing the percentage of structural failure versus the specific internal energy is plotted. Assuming that 20% structural failure of the model equates to a catastrophic failure, this analysis shows that the analyzed section of the Comanche tailfan shroud can withstand an explosion with a specific 10 2 2 internal energy of 2.58 ̂ 10 in Isec . Any potential threat rounds with specific internal energies greater than 2.58 ̂ 1010 in2/sec2 will ose serious threats to the Comanche.
Download or read book Flight Service Evaluation of Composite Helicopter Components written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: An assessment is presented of ten composite tail rotor spars and four horizontal stabilizers exposed to the effects of in-flight commercial service for up to nine years to establish realistic environmental factors for use in future designs. This evaluation is supported by test results of helicopter components and panels which have been exposed to outdoor environmental effects since 1979. Full scale static and fatigue tests were conducted on graphite/epoxy and Kevlar/epoxy composite components removed from Sikorsky Model S-76 helicopters in commercial operations off the Gulf Coast of Louisiana. Small scale static and fatigue tests were conducted on coupons obtained from panels exposed to outdoor conditions in Stratford, CT and West Palm Beach, Florida. The panel materials and ply configurations were representative of the S-76 components. The results are discussed of moisture analyses and strength tests on both the S-76 components and composite panels after up to nine years of outdoor exposure. Full scale tests performed on the helicopter components did not disclose any significant reductions from the baseline strengths. The results increased confidence in the long term durability of advanced composite materials in helicopter structural applications. Mardoian, George H. and Ezzo, Maureen B. Unspecified Center AIRCRAFT PARTS; ATMOSPHERIC EFFECTS; COMPOSITE STRUCTURES; FATIGUE LIFE; GRAPHITE-EPOXY COMPOSITES; HELICOPTER TAIL ROTORS; THERMOSETTING RESINS; FATIGUE TESTS; FULL SCALE TESTS; HELICOPTER DESIGN; MOISTURE; SERVICE LIFE; STABILIZERS (FLUID DYNAMICS); STATIC TESTS...
Download or read book Evaluation of an Army Aviator s Ability to Conduct Ingress and Egress of the RAH 66 Comanche Crew Station While Wearing the Air Warrior Ensemble written by Joshua S. Kennedy and published by . This book was released on 2004-12-01 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The RAH-66 Comanche represented the U.S. Army's next generation state-of-the-art armed reconnaissance helicopter. Likewise, the Air Warrior aviation life support ensemble worn by Army aviators represents a significant improvement in personal clothing and equipment. However, at the intersection of the Comanche's crew stations and the bulkiness of the Air Warrior ensemble lies a potential problem: pilots have difficulty entering and leaving the crew station, especially in an emergency. This study evaluated an Army aviator's ability to conduct ingress and egress of the Comanche while wearing the Air Warrior ensemble. Several operationally relevant combinations of aircrew anthropometry, Air Warrior ensembles, and ingress-egress routes were evaluated for the front and rear crew stations. Jack human-figure modeling and motion capture technology were also used in the evaluation. Mean emergency egress times were found to be well within published military specifications. However, results show that larger males will likely have a significantly more difficult time leaving the aircraft than smaller persons, especially when clothed in the bulkiest Air Warrior configuration. Several operational and design recommendations are made. In February 2004, the Department of the Army cancelled the RAH-66 Comanche program. However, the information contained in this report can be used for ingress and egress testing of new or modified aviation systems.
Download or read book Army Aviation written by Christopher C. Bolkcom and published by . This book was released on 2002 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Helicopter Vertical Stabilizer Design Considerations written by James E. Young and published by . This book was released on 1983 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Helicopter vertical stabilizer design considerations are receiving increasing emphasis from the helicopter community. Recent development programs experienced problems with respect to the empennage. Naval Postgraduate School Helicopter Design Course sophistication demands inclusion of vertical stabilizer parameters. The parameters are addressed in terms of conventional airfoil design considerations such as airfoils section, planform area, aspect ratio, camber, and sweep back angle. Specific to helicopters is the relationship to the tail rotor. The fundamental design tradeoff is maximum vertical stabilizer size to optimize directional stability and flight with zero tail rotor thrust contrasted to minimum size to optimize tail rotor blockage effects. A conceptual design procedure is developed herein. (Author).
Download or read book Structural Analysis of Helicopter Flight and Hangar Decks written by and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication clarifies and modernizes the text in the current Design Data Sheet, DDS 130-2, used to analyze the structural strength of US Navy ship helicopter flight and hangar decks. This document explains the DDS 130-2 procedure to provide a better understanding of the methodology. The DDS 130-2 and this document provide a uniform standard and simplified method for the strength analysis of the helicopter flight and hangar deck structure on US Navy Ships. The analysis method is specifically for helicopter operations. Any other loading conditions or aircraft operations in the handling areas should be considered separately. The DDS 130-2 includes helicopter with both wheeled and skid type landing gear, this paper focuses on helicopters with wheeled gears only.
Download or read book Army Aviation written by Christopher Bolkcom and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Although it has been a high priority Army program, a number of factors have complicated the RAH-66 Comanche program. Since its inception, the program has been restructured several times–postponing the initial operational capability (IOC) and increasing overall program costs. Presently, there is debate within the Army regarding whether the program should be reduced significantly to make funds available to pursue other modernization priorities.
