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Technical Paper

Composite Applications at Bell Helicopter

1979-02-01
790578
Bell Helicopter Textron has used fiber reinforced plastic materials in many applications since the earliest appearance of these materials.
Technical Paper

History of Ice Protection System Design at Bell Helicopter

2003-06-16
2003-01-2093
This is quite significant, especially for low altitude rotorcrafts. Bell Helicopter manufactures and offers a wide range of helicopter models and Tiltrotors. Bell Helicopter has accumulated a large database of experience in research, design and development of ice protection systems for rotorcraft. ...Bell Helicopter has accumulated a large database of experience in research, design and development of ice protection systems for rotorcraft. All Bell Helicopter commercial models propulsion systems and most of the military models are certified/qualified for operation in icing. ...This paper summarizes the many Bell Helicopter icing projects conducted throughout the years through flight test on helicopters as well as analytical and model testing research.
Technical Paper

Assessment of the Dynamic Stability Characteristics of the Bell Model M427 Helicopter Using Parameter Estimation Technology

2002-11-05
2002-01-2916
A joint program between Bell Helicopter Textron Canada and the Flight Research Laboratory of Canada's National Research Council was initiated to address the aerodynamic modelling challenges of the Bell M427 helicopter. ...A joint program between Bell Helicopter Textron Canada and the Flight Research Laboratory of Canada's National Research Council was initiated to address the aerodynamic modelling challenges of the Bell M427 helicopter. The primary objective was to use the NRC parameter estimation technique, based on modified maximum likelihood estimation (MMLE), on a limited set of flight test data to efficiently develop an accurate forward-flight mathematical model of the Bell M427. ...The primary objective was to use the NRC parameter estimation technique, based on modified maximum likelihood estimation (MMLE), on a limited set of flight test data to efficiently develop an accurate forward-flight mathematical model of the Bell M427. The effect of main rotor design changes on the aircraft stability characteristics was also investigated, using parameter estimation.
Technical Paper

Evaluation of Composite Components on the Bell 206L and Sikorsky S-76 Helicopter

1986-10-01
861671
Progress on two programs to evaluate structural composite components in flight service on Bell 206L and Sikorsky S-76 commercial helicopters is described. Forty ship sets of composite components that include the litter door, baggage door, forward fairing, and vertical fin have been installed on Bell Model 206L helicopters that are operating in widely different climates. ...Forty ship sets of composite components that include the litter door, baggage door, forward fairing, and vertical fin have been installed on Bell Model 206L helicopters that are operating in widely different climates. Component installation started in 1981 and selected components are being removed and tested at prescribed intervals over a 10-year evaluation. ...Four horizontal stabilizers and ten tail rotor spars that are production components on the S-76 helicopter are being tested after prescribed periods of service to determine the effects of the operating environment on their performance.
Technical Paper

The Bell Model 222

1977-02-01
770951
This paper describes the design objectives, features and performance of the recently developed Bell Model 222. The Model 222 was designed to meet the needs of the worldwide commercial market. ...The latter refers to the fact that for any altitude at which the helicopter can hover OGE, it can continue to cruise if one engine fails. The first flight was in August 1976 and development is essentially complete. ...The aircraft will be delivered in early 1979 after the most comprehensive test program ever conducted on a commercial helicopter.
Technical Paper

Special Report on Bell ACAP Full-Scale Aircraft Crash Test

1987-12-01
872362
A full-scale aircraft crash test of the Bell ACAP developed under the U.S. Army's Advanced Composite Airframe Program was conducted at NASA Langley Research Center's Impact Dynamics Facility on August 27, 1987. ...The test demonstrated that the Bell ACAP was capable of meeting the U.S. Army's stringent crash survivability requirements of 50-ft/s resultant ground impact velocity (42-ft/s sink speed, 27-ft/s forward velocity, with two-thirds DGW rotor lift) at an aircraft attitude of 10° roll and 10° nose-up pitch without any apparent serious injuries to the occupants. ...The ACAP crash test represents the first time any helicopter has ever been tested to this 50-ft/s impact level with the aircraft attitudes of 10° for both roll and pitch conditions.
Technical Paper

Isolation of Rotor Induced Vibration with the Bell Focal Pylon-Nodal Beam System

1976-02-01
760892
Presently this system is used on two production helicopters, the Bell Models 214 and 206L, on the Model 222 8-place commercial helicopter now in development testing, and on the U. ...The stringent vibration requirements of the military and the desire of the civil customer for a smooth ride has led Bell to develop the NODAMATIC isolation system. The NODAMATIC system consists of a focal pylon to isolate inplane hub shears and hub moments and a nodal beam to isolate vertical hub shears. ...Army YAH-63 Advanced Attack Helicopter. Flight tests have demonstrated that crew station and cabin vibration levels of less than .05g at blade passage frequency can be attained with the NODAMATIC system.
Technical Paper

Producibility of Helicopter Power Transmission Systems

1968-02-01
680675
This paper summarizes the production history of Bell Helicopter Co.’s Model UH-1 (Huey) helicopter transmission, compares the producibility of the Huey transmission system with the estimated producibility of new conventional and unconventional systems, and outlines the responsibilities of the transmission designer in adding producibility to his usual design considerations of weight, efficiency, reliability, and cost.
Technical Paper

Noise Reduction Possibilities for a Light Helicopter

1969-10-06
690683
Results of a preliminary design study to establish the degree of quieting possible in a light helicopter are discussed. The study consists of analytical investigations of noise-reduction measures and of the penalties in performance and mission capabilities. ...Design data are presented for modified and redesigned versions of the OH-58A Light Observation Helicopter (LOH). The modified version is a test bed for verifying the predicted noise reductions, while the redesignec version shows the extent of changes and increase in weight that are necessary to give an operational LOH the performance and payload of the OH-58A.
Technical Paper

High Speed Machining of Helicopter Gearcases

2004-09-21
2004-01-2826
High speed machining of aluminum and magnesium helicopter gearcases was experimentally demonstrated to be five times more productive than contemporary conventional commercial practice for suitable operations.
Standard

Helicopter Mission Definition

1997-12-01
CURRENT
ARP1352
The purpose of this recommended practice is to establish a standard format for the presentation of helicopter mission data, which will provide data required to establish airframe and/or engine component life.
Technical Paper

Crash Impact Characteristics of Helicopter Composite Structures

1983-02-01
830749
This paper describes the results of a research program to investigate the crash impact behavior of helicopter composite structures designed to meet the U.S. Army’s crashworthiness requirements specified in MIL-STD-1290. ...The program included design, fabrication, and crash testing of two full-scale composite helicopter cabin sections. The drop test conditions for the two cabin sections were representative of the 42 ft/s vertical crash impact velocity requirement specified in MIL-STD-1290 assuming the landing gear had slowed the aircraft from 42 ft/s to 30 ft/s prior to fuselage contact. ...Based on the good crash impact performance of the composite cabins and the comparison of analytical and test results, KRASH proved to be a useful and reasonably accurate analysis tool for the design of helicopter composite structures to meet the Army’s crash-worthiness requirements.
Standard

Helicopter Power Assurance

2023-01-20
CURRENT
AIR4083A
This SAE Aerospace Information Report (AIR) defines helicopter turboshaft engine power assurance theory and methods. Several inflight power assurance example procedures are presented. ...These procedures vary from a very simple method used on some normal category civil helicopters, to the more complex methods involving trend monitoring and rolling average techniques.
Standard

HELICOPTER ENGINE MOUNTING

2020-01-31
CURRENT
AIR4172
This Aerospace Information Report (AIR) reviews the requirements to be satisfied by the engine mount systems and provides an outline of some suitable methods. Factors such as drive shaft alignment, engine expansion, mount crashworthiness, vibration isolation, and other effects on the installation are discussed.
Standard

Helicopter FUEL Economy Evaluation

1998-02-01
CURRENT
AS1516
The purpose of this standard is to provide a method of evaluating helicopter fuel economy which accounts for the significant technical variables in helicopter and powerplant design.
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