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Flight Investigation Of The Effect Of Tail Boom Strakes On Helicopter Directional Control
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Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722240004 Total Pages :44 pages Book Rating :4.2/5 (4 download)
Book Synopsis Flight Investigation of the Effect of Tail Boom Strakes on Helicopter Directional Control by : National Aeronautics and Space Administration (NASA)
Download or read book Flight Investigation of the Effect of Tail Boom Strakes on Helicopter Directional Control written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-03 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: A joint U.S. Army/NASA flight investigation was conducted utilizing a single-rotor helicopter to determine the effectiveness of horizontally mounted tail boom strakes on directional controllability and tail rotor power during low-speed, crosswind operating conditions. Three configurations were investigated: (1) baseline (strakes off), (2) single strake (strake at upper shoulder on port side of boom), and (3) double strake (upper strake plus a lower strake on same side of boom). The strakes were employed as a means to separate airflow over the tail boom and change fuselage yawing moments in a direction to improve the yaw control margin and reduce tail rotor power. Crosswind data were obtained in 5-knot increments of airspeed from 0 to 35 knots and in 30 deg increments of wind azimuth from 0 deg to 330 deg. At the most critical wind azimuth and airspeed in terms of tail rotor power, the strakes improved the pedal margin by 6 percent of total travel and reduced tail rotor power required by 17 percent. The increase in yaw control and reduction in tail rotor power offered by the strakes can expand the helicopter operating envelope in terms of gross weight and altitude capability. The strakes did not affect the flying qualities of the vehicle at airspeeds between 35 and 100 knots. Kelly, Henry L. and Crowell, Cynthia A. and Yenni, Kenneth R. and Lance, Michael B. Langley Research Center DA PROJ. 1L1-62211-A-47-A; RTOP 505-59-36-01...
Book Synopsis Flight Investigation of the Effect of Tail Boom Strakes on Helicopter Directional Control by : Henry L. Kelley
Download or read book Flight Investigation of the Effect of Tail Boom Strakes on Helicopter Directional Control written by Henry L. Kelley and published by . This book was released on 1993 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Adm Nasa Publisher :Independently Published ISBN 13 :9781792670152 Total Pages :38 pages Book Rating :4.6/5 (71 download)
Book Synopsis Development in Helicopter Tail Boom Strake Applications in the Us by : National Aeronautics and Space Adm Nasa
Download or read book Development in Helicopter Tail Boom Strake Applications in the Us written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-12-31 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of a strake or spoiler on a helicopter tail boom to beneficially change helicopter tail boom air loads was suggested in the United States in 1975. The anticipated benefits were a change of tail boom loads to reduce required tail rotor thrust and power and improve directional control. High tail boom air loads experienced by the YAH-64 and described in 1978 led to a wind tunnel investigation of the usefullness of strakes in altering such loads on the AH-64, UH-60, and UH-1 helicopters. The wind tunnel tests of 2-D cross sections of the tail boom of each demonstrated that a strake or strakes would be effective. Several limited test programs with the U.S. Army's OH-58A, AH-64, and UH-60A were conducted which showed the effects of strakes were modest for those helicopters. The most recent flight test program, with a Bell 204B, disclosed that for the 204B the tail boom strake or strakes would provide more than a modest improvement in directional control and reduction in tail rotor power. Wilson, John C. and Kelley, Henry L. and Donahue, Cynthia C. and Yenni, Kenneth R. Langley Research Center NASA-TM-101496, NAS 1.15:101496, AVSCOM-TM-88-B-014 RTOP 505-61-51-10...
Book Synopsis Development in Helicopter Tail Boom Strake Applications in the US by : John C. Wilson
Download or read book Development in Helicopter Tail Boom Strake Applications in the US written by John C. Wilson and published by . This book was released on 1988 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Effect of Tailboom Strakes and Vertical Fin Modifications on the Performance and Handling Qualities of OH-58 Helicopters by :
Download or read book The Effect of Tailboom Strakes and Vertical Fin Modifications on the Performance and Handling Qualities of OH-58 Helicopters written by and published by . This book was released on 2008 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Bell OH-58D helicopter is used in the armed reconnaissance role by the U.S. Army worldwide. Operations in support of this mission require the aircraft to be operated at a hover for extended periods of time at high altitude and in hot conditions. This places large demands on a power limited aircraft and increases pilot workload, especially in the pointing task so important to weapons delivery. The addition of aerodynamic modifications provides an inexpensive and effective method of reducing power required and pilot workload. An investigation was conducted to determine the effects of adding tailboom strakes and a vertical fin modification (FastFin®) to a Bell OH-58D. The effect of the combined devices on helicopter performance, vibration and handling qualities was evaluated to determine any decrease in power vs. power available (increased power margin). The strakes and modified fin were attached to the tailboom in such a manner as to alter the flow pattern of air passing over the tailboom. This change in flow pattern reduced the anti-torque requirements of the tail rotor. This in turn reduced the overall power requirement. The modified fin and strake combination reduced the vortices and turbulence at the tailboom and resulted in lower pilot workload and vibration in an out-of-ground-effect hover. This study also evaluated the effects on performance and handling characteristics of the helicopter. Testing included hover, low airspeed forward, rearward, sideward flight and level forward flight power measurements and handling qualities using modified Cooper-Harper and Vibration Assessment Rating (VAR) scales. Results showed an overall improvement in handling qualities and vibration levels at critical wind azimuth angles in low airspeed flight. For out-of-ground-effect (OGE) hover, there was also a 2-3% reduction in power required due to the improved aerodynamic efficiency of the modified fin and strake combination.
Book Synopsis A Wind-tunnel Investigation of Helicopter Directional Control in Rearward Flight in Ground Effect by : Robert J. Huston
Download or read book A Wind-tunnel Investigation of Helicopter Directional Control in Rearward Flight in Ground Effect written by Robert J. Huston and published by . This book was released on 1971 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was conducted in the Langley full-scale tunnel to study the aerodynamics that produce directional-control problems for a helicopter with a tail rotor in low-speed rearward flight in ground effect. A helicopter model mounted close to the tunnel floor was tested in tail winds from 0 to 25 knots.
Book Synopsis Aerodynamic Effect of Strakes on Two-Dimensional Tail Boom Models of the Oh-58a and the Oh-58d Helicopters by : National Aeronautics and Space Adm Nasa
Download or read book Aerodynamic Effect of Strakes on Two-Dimensional Tail Boom Models of the Oh-58a and the Oh-58d Helicopters written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-22 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: During hover and low speed flight, helicopters experience significant aerodynamic forces on the tail boom caused by the wake from the main and tail rotors and by crosswinds. These effects were simulated during a study conducted in the Langley 14 by 22 Foot Subsonic Tunnel on a 136 percent scaled 2-D tail boom model with cross sections representative of those on the U.S. Army OH-58A and the OH-58D helicopters. The effects of longitudinal strakes attached to the cross sections were studied. To obtain the aerodynamic forces acting on the cross sections, the flow incidence range on the scaled models was varied from -45 to 90 degrees and the models were tested through a dynamic pressure range of 5 to 15 psf. The results of the OH-58A and the OH-58D configurations show a significant improvement at conditions which represent right sideward flight by reducing the adverse aerodynamic side force when the strakes are installed. These data were used to calculate a change in tail rotor power for the full scale flight vehicle and indicated approx. a 5 to 6 percent average savings in right sideward flight for the critical velocity range of 0 to 30 knots. Increases in the tail boom normal force were noted due to the strakes. The results indicate a potential for reducing the directional control and tail rotor thrust required in the critical hover and right sideward flight speed range with a calculated minimum increase to main rotor power required and an overall net improvement in power of 0.5 percent for both the OH-58A and OH-58D. Crowell, Cynthia A. and Kelley, Henry L. Langley Research Center DA PROJ. 1L1-62211-A-47-A; RTOP 505-61-51-10...
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1990 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Aerodynamic Characteristics of Several Current Helicopter Tail Boom Cross Sections Including the Effect of Spoilers by : John C. Wilson
Download or read book Aerodynamic Characteristics of Several Current Helicopter Tail Boom Cross Sections Including the Effect of Spoilers written by John C. Wilson and published by . This book was released on 1986 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamic characteristics were determined of three cylindrical shapes representative of tail boom cross sections of the AH-64, UH-60, and UH-1H helicopters. Forces and pressures were measured in a wind-tunnel investigation. Data was obtained for a flow incidence range from -45 to 90 deg and a dynamic pressure range from 1.5 to 50 psf. These ranges provided data representative of full-scale Reynolds numbers and the full range of flow incidence to which these helicopter tail boom shapes would be subjected at low flight speeds. The effects of protuberances such as tail rotor drive-shaft covers and spoilers were evaluated. The data indicate that significant side loads on tail booms of helicopters can be generated and that the addition of spoilers can beneficially alter the side loads. Although an increase in vertical drag occurs, the net effect through reduction of tail rotor thrust required can be an improvement in helicopter performance. Keywords: Rotorcraft; Aerodynamics; Stability and control; Helicopters; Tail booms.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Exploratory Investigation of Aerodynamic Characteristics of Helicopter Tail Boom Cross-Section Models with Passive Venting by : Daniel W. Banks
Download or read book Exploratory Investigation of Aerodynamic Characteristics of Helicopter Tail Boom Cross-Section Models with Passive Venting written by Daniel W. Banks and published by . This book was released on 2000 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two large-scale, two-dimensional helicopter tail boom models were used to determine the effects of passive venting on boom down loads and side forces in hovering crosswind conditions. The models were oval shaped and trapeziodal shaped. Completely porous and solid configurations, partial venting in various symmetric and asymmetric configurations, and strakes were tested. Calculations were made to evaluate the trends of venting and strakes on power required when applied to a UH-60 class helicopter. Compared with the UH-60 baseline, passive venting reduced side force but increased down load at flow conditions representing right sideward flight. Selective asymmetric venting resulted in side force benefits close to the fully porous case. Calculated trends on the effects of venting on power required indicated that the high asymmetric oval configuration was the most effective venting configuration for side force retention, and the high asymmetric with a single strake was the most effective for overall power reduction. Also, curves of side force versus flow angle were noticeably smoother for the vented configurations compared with the solid baseline configuration; this indicated a potential for smoother flight in low-speed crosswind conditions.
Book Synopsis Aerodynamic Effect of Strakes on Two-dimensional Tail Boom Models of the OH-58A and the OH-58D Helicopters by : Cynthia A. Crowell
Download or read book Aerodynamic Effect of Strakes on Two-dimensional Tail Boom Models of the OH-58A and the OH-58D Helicopters written by Cynthia A. Crowell and published by . This book was released on 1990 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781720520146 Total Pages :52 pages Book Rating :4.5/5 (21 download)
Book Synopsis Exploratory Investigation of Aerodynamic Characteristics of Helicopter Tail Boom Cross-Section Models with Passive Venting by : National Aeronautics and Space Administration (NASA)
Download or read book Exploratory Investigation of Aerodynamic Characteristics of Helicopter Tail Boom Cross-Section Models with Passive Venting written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-31 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two large-scale, two-dimensional helicopter tail boom models were used to determine the effects of passive venting on boom down loads and side forces in hovering crosswind conditions. The models were oval shaped and trapezoidal shaped. Completely porous and solid configurations, partial venting in various symmetric and asymmetric configurations, and strakes were tested. Calculations were made to evaluate the trends of venting and strakes on power required when applied to a UH-60 class helicopter. Compared with the UH-60 baseline, passive venting reduced side force but increased down load at flow conditions representing right sideward flight. Selective asymmetric venting resulted in side force benefits close to the fully porous case. Calculated trends on the effects of venting on power required indicated that the high asymmetric oval configuration was the most effective venting configuration for side force reduction, and the high asymmetric with a single strake was the most effective for overall power reduction. Also, curves of side force versus flow angle were noticeable smoother for the vented configurations compared with the solid baseline configuration; this indicated a potential for smoother flight in low-speed crosswind conditions.Banks, Daniel W. and Kelley, Henry L.Armstrong Flight Research Center; Langley Research CenterAERODYNAMIC CHARACTERISTICS; HELICOPTERS; STRAKES; AERODYNAMIC CONFIGURATIONS; TWO DIMENSIONAL MODELS; TAIL ASSEMBLIES; CROSS FLOW; FLIGHT CONDITIONS; WIND DIRECTION; VENTING; ASYMMETRY
Book Synopsis Aerodynamic Effect of Strakes on Two-dimensional Tail Boom Models of OH-58A and OH-58D Helicopters by : Cynthia A. Crowell
Download or read book Aerodynamic Effect of Strakes on Two-dimensional Tail Boom Models of OH-58A and OH-58D Helicopters written by Cynthia A. Crowell and published by . This book was released on 1990 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Journal of the American Helicopter Society by : American Helicopter Society
Download or read book Journal of the American Helicopter Society written by American Helicopter Society and published by . This book was released on 1992 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Tech Briefs written by and published by . This book was released on 1986 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Two-dimensional Aerodynamic Characteristics of Several Polygon-shaped Cross-sectional Models Applicable to Helicopter Fuselages by : Henry L. Kelley
Download or read book Two-dimensional Aerodynamic Characteristics of Several Polygon-shaped Cross-sectional Models Applicable to Helicopter Fuselages written by Henry L. Kelley and published by . This book was released on 1992 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
