Army Preliminary Evaluation III and IV YCH-47C Medium Transport Helicopter
Army Preliminary Evaluation III and IV YCH-47C Medium Transport Helicopter

Author: Jerry L. Jester

Publisher:

Published: 1970

Total Pages: 148

ISBN-13:

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Army Preliminary Evaluation (APE) consisted of vibration noise level tests and a re-evaluation of the stability and control characteristics modified by the incorporation of engineering changes to correct the handling qualities deficiencies found during APE II. APE IV was a re-evaluation of the vibration characteristics which was required because of structural modifications incorporated in the aircraft following APE III. The helicopter showed significant improvements in trimmability, static and dynamic longitudinal stability and lateral-directional stability as compared to aircraft flown during APE I and II. The longitudinal stability improvements permitted sustained hands off flight. The vibration levels experienced during APE IV were improved over APE III. The aircraft met all requirements except two of the detail specification and two of the military specification.

Engineering Flight Test of the YCH-47C Medium Transport Helicopter. Army Preliminary Evaluation I.
Engineering Flight Test of the YCH-47C Medium Transport Helicopter. Army Preliminary Evaluation I.

Author: Jerry L. Jester

Publisher:

Published: 1968

Total Pages: 90

ISBN-13:

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Army Preliminary Evaluation I was conducted to verify the performance guarantees, obtain limited handbook data and evaluate the mission effectiveness of the YCH-47C helicopter. The maximum cruise speed capability was 155 KTAS and limited by heavy cockpit vibration. The outstanding 95 degree Fahrenheit day in ground effect and out of ground effect hover capability enhances the mission effectiveness of the aircraft. The flight envelope release V(NE) for all gross weights tested at 245 rpm rotor speed and low and high altitudes was not attained. The airspeed was limited by as much as 15 KTAS due to heavy cockpit vibration, but not to the extent that the mission effectiveness of the helicopter would be seriously degraded. The V(NE) was easily exceeded for all gross weights tested at 235 rpm rotor speed-high altitudes with no vibration limitations encountered.

Engineering Flight Test of the YCH-47C Medium Transport Helicopter. Army Preliminary Evaluation II.
Engineering Flight Test of the YCH-47C Medium Transport Helicopter. Army Preliminary Evaluation II.

Author: Jerry L. Jester

Publisher:

Published: 1969

Total Pages: 204

ISBN-13:

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The evaluation consisted of limited level flight performance tests and stability and control tests. Within the scope of tests all but six stability and control requirements of the detail and military specifications were met. Correction of two deficiencies is mandatory for acceptable mission capabilities. These deficiencies are the static and dynamic longitudinal stability improved helicopter capabilities. Safety of flight was affected by aft rotor blade stall characteristics in maneuvering flight and bank angles above 30 degrees and requires a reduction in maximum bank angles permitted. High aft rotor flight control component stress levels associated with maneuvering flight and operation at limit airspeeds requires that a visual flight loads display be incorporated in the cockpit.

Engineering Flight Test of the YCH-47B Helicopter Army Preliminary Evaluation I, II and III.
Engineering Flight Test of the YCH-47B Helicopter Army Preliminary Evaluation I, II and III.

Author: Norman A. Mattmuller

Publisher:

Published: 1969

Total Pages: 166

ISBN-13:

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The Army Preliminary Evaluation of the YCH-47B helicopter was conducted by the US Army Aviation Systems Test Activity at Philadelphia, Pennsylvania in three phases during the period 1 March 1967 to 31 August 1967. The improvements in hover and level flight performance were defined and the change in flying qualities from those of the CH-47A helicopter were evaluated. An objectionable level of noise and vibration was encountered during testing; however, a significant reduction in vibration was achieved by the reduction of recommended rotor rpm from 230 to 225. An expansion of the 16,000 pound external load flight envelope to that of the helicopter with internal loads was substantiated with the exception of bank angle limitations. As a result of stress checks performed in turn maneuvers, the bank angle envelope was reduced to avoid excessive fatigue damage on aft rotor head control components. (Author).

Army Preliminary Evaluation YAH-IQ Helicopter with a Flat-Plate Canopy
Army Preliminary Evaluation YAH-IQ Helicopter with a Flat-Plate Canopy

Author: James R. Arnold

Publisher:

Published: 1975

Total Pages: 40

ISBN-13:

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The United States Army Aviation Engineering Flight Activity conducted a limited evaluation of the level flight performance and handling qualities of a YAH-1Q helicopter with a flat-plate canopy from 17 through 19 June 1975 at the Bell Helicopter Company flight test facility at Arlington, Texas. During the test program, eleven flights for a total of 4.4 productive hours were flown. A loss in maximum airspeed for level flight was determined when compared to the AH-1G (Bell Helicopter Company data indicate 5 to 7 knots). The primary effect of the flat-plate canopy on handling qualities was a noticeable decrease in directional stability. The one deficiency determined during the evaluation was the internal reflection from external light sources on the flat-plate canopy during night flight. Five shortcomings were noted during the evaluation. Further testing should be conducted to determine the effect of the decreased directional stability on the accuracy of rocket fire.

Army Preliminary Evaluation, Prototype OH-58A Helicopter with XM27E1 Weapon Subsystem
Army Preliminary Evaluation, Prototype OH-58A Helicopter with XM27E1 Weapon Subsystem

Author: John Nagata

Publisher:

Published: 1970

Total Pages: 59

ISBN-13:

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The Army Preliminary Evaluation of the OH-58A prototype helicopter was conducted in the vicinity of Arlington, Texas, during the period 26 June to 9 July 1969. Thirteen test flights were conducted for a total of 14.5 hours of which 9.1 hours were productive. The evaluation consisted of limited quantitative and qualitative stability and control tests in the armed scout configuration only. The handling qualities of the OH-58A are satisfactory for the accomplishment of the armed scout mission. (Author).