A rotorcraft that resembles a catamaran has taken the top prize in a NASA aeronautics competition for college students to develop a multi-purpose aircraft.
The entry by ten students at Virginia Tech in Blacksburg, Va., met the competition's challenge to design a civilian aircraft that could rescue up to 50 survivors in the event of a natural disaster, hover to help rescue missions, land on ground or water, travel 920 miles and cruise at speeds up to 345 miles an hour. The amphibious tilt-rotor vehicle also had to be able to fight fires by siphoning water into an internal tank, then dumping it after airborne.
NASA's Aeronautics Mission Directorate in Washington sponsored the competition through the Subsonic Rotary Wing Project in its Fundamental Aeronautics Program. The below are the three winning designs from first to third.
V.T. R.A.F.T. Design
The design of the proposed amphibious tiltrotor aircraft was conducted by a team of 10 undergraduate students as a capstone design project. The aircraft was designed to meet requirements specified by the NASA Amphibious Tiltrotor Competition. The aircraft is required to take off and land vertically on both water and land, as well as having an 800 nm range and a cruise speed of 300 kts. The payload is up to 50 passengers or water for firefighting operations. Specifics such as the operational sea state, maximum altitude, and total water capacity were later defined by the study based on currently existing aircraft and technical analysis.
A dual fuselage concept, named the Vertical Transport Rescue Amphibious Firefighting Tiltrotor (V.T. R.A.F.T.) was proposed as the design best suited to fulfill the mission. The aircraft can perform vertical flight operations with a maximum takeoff gross weight (TOGW) of 62,460 lb. The aircraft can accommodate 50 passengers or 12,000 lb of water, in addition to 10,175 lb of fuel. Two 6150 shp turboshaft engines power the aircraft. Each engine is located at the wingtip inside the nacelles, which are capable of rotating at a rate of 3.0°/sec. This allows the aircraft to change from helicopter mode to airplane mode in 30 sec. The main cabin is not pressurized; however, for high altitude operations without passengers oxygen is supplied to the flight crew.
Water stability in a sea state of up to four was a major concern and was instrumental in the choice of a dual fuselage concept. This configuration eliminates the need for pontoons, which reduces drag and aircraft complexity. Additionally, the dual fuselage design reduced aerodynamic loading on the main spar and enhanced aerial rescue capabilities by providing a rescue area shielded from the rotor downwash.
Although not mandated by the competition, the aircraft is designed to be able to receive aerial refueling and perform aero-medical operations. In addition to vertical takeoff and landing the aircraft is designed to perform a short takeoff from land based facilities, increasing the TOGW to 70,000 lb. Future study and analysis should be conducted to determine the engines capacity to avoid the ingestion of water mist while hovering over water as well as further investigation of wing flutter phenomenon for this design.
Page
CAESAR Design
As the tiltrotor concept continues to be operationally validated and commercially certified, the stage is set to produce a viable and reliable vehicle to bridge the gap between existing rotary-wing and fixed-wing capabilities regarding speed, payload, and range to inaccessible areas, particularly for rescue operations. Current helicopter technology, with its efficient vertical flight and hover capability, provides unsurpassed effectiveness in short to medium range rescue operations into inaccessible or remote areas, saving lives which would otherwise be lost. Similarly, fixed-wing aircraft are highly efficient at rapidly moving critical payloads over long distances, although prepared landing surfaces are typically required.
Without attempting to replace either of these proven platforms, an amphibious tiltrotor promises a blend of the range and speed of a standard fixed wing aircraft with the vertical capabilities of a helicopter, adding flexibility to disaster relief and rescue operations. To be effective, this vehicle must be an adaptable workhorse to fill a large variety of needs throughout a lengthy service life, and be robust and reliable enough to ensure that it can perform as needed, when needed. It should act as an enabler to Incident Commanders, as an economical resource with minimal restrictions on its employment or service environment.
In answer to this call, the Georgia Institute of Technology presents the Civilian Aid, Emergency Search and Rescue (CAESAR) aircraft, an amphibious Quad-Tiltrotor (QTR) capable of worldwide self-deployment and operations in Sea-State 3. With the ability to carry up to 50+ personnel or 10,000+ lbs of payload in excess of 800 nm at speeds of 300 knots, this aircraft is specifically designed as a rescue aircraft that can respond more quickly and rescue more people per mission than anything else available.
Being intended for certification and low rate initial production within 10 years and designed for reliability and maintainability as key design factors, complex, unreliable, overly-optimistic, impractical, and cost-prohibitive design options were ruled out. Conservative estimates were applied throughout the conceptual design process to ensure the validity of the concept as it progresses to detailed design. Preliminary design of some systems was achieved, confirming conceptual estimates. Innovative technologies were inserted where needed primarily due to lack of current data or inadequate performance. The basic intent of this design was to merge current or near-term state of the art technologies into a practical solution to today‟s disaster relief requirements.
Primary design trade-offs involved performance versus cost and reliability, disk-loading versus vehicle size, amphibious stability versus aerodynamic performance, and corrosion resistance versus cost. A major focus of this study was to validate the handling qualities of the medium-lift QTR configuration for a search and rescue, disaster relief platform. This was accomplished through FLIGHTLAB analysis with real-time flight simulation conducted by Liverpool University
AVATAR Design
The field of search and rescue has long been dominated by the helicopter. Vertical takeoff and landing (VTOL) aircraft are the next step in search and rescue technology. They can hover and maneuver at low airspeeds, but can cruise at much faster speeds and lift larger loads than traditional helicopters. The Advanced Virginia Amphibious Tilt Rotor (AVATR) Soterion is a versatile, innovative rotorcraft designed to push the boundaries of rotorcraft cruise speed, range, and passenger capacity.
Innovative design features allow the Soterion to meet key performance metrics such as an 863 nm range at a 300 knot cruise speed, mounted engines are shafted to wing-tip nacelles housing variable diameter rotors (VDRs) that decrease in diameter during hover-to-cruise transition. The strategic engine location minimizes salt water ingestion during water landings and keeps engine exhaust directed away from water and passengers. In this configuration, unlike the V-22, the engines are fixed and only the rotor nacelles rotate. State-of-the-art VDRs combined with continuously variable transmissions provide a solution for the conflicting requirements of vertical and forward flight.
The multifunctional nature of the Soterion will greatly enhance disaster relief response. Earthquakes, hurricanes, and other catastrophes often destroy ground and air transportation infrastructure, making VTOL aircraft an essential part of emergency relief. The Soterion can take off vertically in short spaces, giving it the ability to pick up people from rooftops and uneven terrain for which a conventional landing is impossible.
Its large passenger capacity makes it a valuable tool for sea rescues and disaster zones because it has enough cargo space to include medical and transport equipment. Its increased range (863 nm) and high cruise speed (300 kts) make it ideal for long range rescues. The Soterion also features a cargo area designed to rapidly adapt to multi-mission specifications ranging from large rescue operations to firefighting. In addition to the modular water tanks that can be inserted for firefighting missions, the Soterion houses a scooping mechanism for the intake, mixing, and dispersal of fire retardant.
The conceptual design presented in this report meets and exceeds the requirements for a versatile amphibious tiltrotor capable of responding to natural and man-made disasters. The AVATR Soterion is a pioneering solution to civilian search-and-rescue demands
The conceptual design presented in this report meets and exceeds the requirements for a versatile amphibious tiltrotor capable of responding to natural and man-made disasters. The AVATR Soterion is a pioneering solution to civilian search-and-rescue demands
No comments:
Post a Comment