Browse Topic: Helicopters
A tested method of data presentation and use is described herein. The method shown is a useful guide, to be used with care and to be improved with use.
Airbus Marignane, France laurence.petiard@airbus.com
This SAE Aerospace Information Report (AIR) defines the helicopter bleed air requirements which may be obtained through compressor extraction and is intended as a guide to engine designers.
This document describes a method to calculate noise level adjustments at locations behind an airplane (described by an angular offset or directivity) at the start of takeoff roll (SOTR). This method is derived from empirical data from jet aircraft (circa 2004), most of which are configured with wing-mounted engines with high by-pass ratios (Lau, et al., 2012). Methods are also described which apply to modern turboprop aricraft. Calculations of other propagation-related adjustments required for aircraft noise prediction models are described in AIR1845A, ARP5534, ARP866A, and AIR5662.
Slowed rotors – traditionally associated with autogyros and gyroplanes – have long been recognized as one potential solution for high-speed helicopters (200-300 knots). During the 1950s–70s, there were several significant programs that led to the development of high-speed helicopters with thrust and lift compounding. The key technology barriers common to all were extremely high fuel consumption due to high advancing side drag and large reverse flow, complexities associated with RPM reduction, large blade motions during RPM reduction, and unexplained but catastrophic aeroelastic instabilities of rigid rotors (Cheyenne). None of these helicopters entered regular production.
In August 2011, a US CH-47 Chinook helicopter began its descent in a remote corner of Afghanistan to insert elite Special Forces soldiers at an important objective. Unseen by the aircrew or US reconnaissance drones, a Taliban operative fired a Rocket Propelled Grenade (RPG) at the landing Chinook aircraft, causing it to lose control and crash, killing all 38 service members on board.
This SAE Aerospace Recommended Practice (ARP) recommends a methodology to be used for the design, analysis and test evaluation of modern helicopter gas turbine propulsion system stability and transient response characteristics. This methodology utilizes the computational power of modern digital computers to more thoroughly analyze, simulate and bench-test the helicopter engine/rotor system speed control loop over the flight envelope. This up-front work results in significantly less effort expended during flight test and delivers a more effective system into service. The methodology presented herein is recommended for modern digital electronic propulsion control systems and also for traditional analog and hydromechanical systems.
The Mars Perseverance rover incorporates new design advances since Curiosity landed on the Red Planet, including a Mars Helicopter. Tech Briefs spoke with NASA’s Keith Comeaux, Deputy Project Chief Engineer, to learn more about these new technologies.
Since, ice accretion can significantly degrade the performance and the stability of an airborne vehicle, it is imperative to be able to model it accurately. While ice accretion studies have been performed on airplane wings and helicopter blades in abundance, there are few that attempt to model the process on more complex geometries such as fuselages. This paper proposes a methodology that extends an existing in-house Extended Messinger solver to complex geometries by introducing the capability to work with unstructured grids and carry out spatial surface streamwise marching. For the work presented here commercial solvers such as STAR-CCM+ and ANSYS Fluent are used for the flow field and droplet dispersed phase computations. The ice accretion is carried out using an in-house icing solver called GT-ICE. The predictions by GT-ICE are compared to available experimental data, or to predictions by other solvers such as LEWICE and STAR-CCM+. Three different cases with varying levels of
Jasmin Moghbeli’s astronaut class graduated in January 2020 — the first class to graduate since the agency announced the Artemis program. She holds a BS degree in aerospace engineering with information technology from the Massachusetts Institute of Technology and a MS in engineering science in aerospace engineering from the Naval Postgraduate School. Moghbeli was commissioned as a Second Lieutenant in the United States Marine Corps in 2005 upon completion of her undergraduate degree. An AH-1W Super Cobra helicopter pilot and Marine Corps test pilot, Moghbeli served in Operation Enduring Freedom in Afghanistan from 2009 to 2010. At the time of her selection as an astronaut candidate, Moghbeli was testing H-1 helicopters. She has accumulated more than 150 combat missions and 2,000 hours of flight time in more than 25 different aircraft. She is eligible for assignment to missions destined for the International Space Station, the Moon, and ultimately, Mars.
It is recommended that all helicopter engine development programs include an evaluation of engine starting requirements. The evaluation should include starting requirement effects on helicopter weight, cost, and mission effectiveness. The evaluation should be appropriate to the engine stage of development.
Composite materials are desirable for aeronautical and aerospace applications for many reasons including their high strength-to-weight ratios, fatigue and corrosion resistance, design adaptability, and performance capabilities in harsh environments. Because of these qualities, composites are useful in many applications such as in armor, helmets, and helicopters, and as structural components.
By mimicking the outer coating of pearls (nacre or mother of pearl), researchers created a lightweight plastic that is 14 times stronger and eight times lighter (less dense) than steel. It could be applicable to vests, helmets, and other types of body armor as well as protective armor for ships, helicopters, and other vehicles.
Reconfigurable tooling frames consisting of steel box sections and bolted friction clamps offer an opportunity to replace traditional expensive welded steel tooling. This well publicized reconfigurable reusable jig tooling has been investigated for use in the assembly of a prototype compound helicopter wing. Due to the aircraft configuration, the wing design is pinned at both ends and therefore requires a higher degree of end to end accuracy, over the 4m length, than conventional wings. During the investigation some fundamental issues are approached, including: Potential cost savings and variables which effect the business case. Achievable Jig accuracy. Potential sources of instability that may affect accuracy over time. Repeatability of measurements with various features and methods. Typical jig stability over 24hrs including effects of small temperature fluctuations. Deflections that occur due to loading. The cost benefit of reusable tooling in a low volume prototype scenario is
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