Neutral Point and Stability. [4] The altitude reached was more than 11,000 feet (3,400 m) — or more than 2 miles (3.2 km) — above the previous altitude record for sustained flight by a winged aircraft. Three Pathfinder Plus flights were conducted at the PMRF. The crash of the Helios aircraft was attributed to many factors including complex aero-propulsive-elastic interactions with rigid-body flight dynamics [24]. The NASA Centurion was the third aircraft developed as part of an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. The Helios Prototype flying wing is shown over the Pacific Ocean during its first test flight on solar power from the U.S. Navy's Pacific Missile Range Facility in Hawaii. In contrast to Helios 1, Helios 2, flew about 1.9 million miles (3 million kilometers) closer to the Sun, achieving perihelion April 17, 1976, at a distance of 0.29 AU (about 27 million miles or 43.432 million kilometers), a distance that made Helios 2 the record holder at that time for the closest flyby of the Sun. [1], The Helios Prototype shared the same 8-foot (2.4 m) wing chord (distance from leading to trailing edge) as its Pathfinder and Centurion predecessors. Alternate Names. [1], The all-wing aircraft was assembled in six sections, each about 41 feet (12 m) long. The airfoil upper and lower surfaces meet at the leading and trailing edges. FUN3D is a NASA developed unstructured flow solver that has been around and in use for more than two decades. Helios updates are available at /centers/dfrc/Newsroom/ResearchUpdate/Helios/index.html, Last Modified: September 1, 2004 Speeding up the outer-panel motors caused the aircraft to pitch down and begin a descent. To meet the unique needs of solar energy airplane, carbon fiber was usually used to manufacture the fuselage. ED01 0230-3 NASA Photo by Carla Thomas The Helios Prototype Aircraft begins a northerly climb over Ni’ihau Island, Hawaii. To this end, the Helios Prototype could be configured in two different ways. FUN3D Manual :: Chapter 1: Overview and Getting Started - NASA [3] These cells featured a rear-contact cell design that placed wires on the underside of the cells, so as not to obstruct the cells' exposure to solar radiation. Most of the vehicle structure was recovered except the hydrogen–air fuel cell pod and two of the ten motors, which sank into the ocean."[3]. In addition, the aircraft spent more than 40 minutes above 96,000 feet (29,000 m). The aircraft is the culmination of a progressive development of several designs intended to explore utilization of high-endurance, high-altitude aircraft for communications relay purposes. I guess at some point there is not enough air to get lifted. #! AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. must be located in front of the c/4 point, which is also called neutral point (n.p. The Helios Prototype flying wing is shown moments after takeoff, beginning its first test flight on solar power from the U.S. Navy's Pacific Missile Range Facility in Hawaii. Helios Prototype crew chief Marshall MacCready of AeroVironment, Inc., carefully monitors motor runs during ground checkout of the solar-powered flying wing prior to its first flight in Hawaii. Helios Prototype: On August 13, 2001 the Helios prototype set a world-record by achieving sustained flight at more then 96,000 feet. [1], The Helios Prototype is an ultra-lightweight flying wing aircraft with a wingspan of 247 feet (75 m), longer than the wingspans of the U.S. Air Force C-5 military transport (222 feet (68 m) or the Boeing 747 (195 or 224 feet (59 or 68 m), depending on the model), the two largest operational aircraft built in the United States. The larger wing on the Helios Prototype accommodated more solar arrays to provide adequate power for the sun-powered development flights that followed. The aircraft’s design airspeed was subsequently exceeded and the resulting high dynamic pressures caused the wing leading edge secondary structure on the outer wing panels to fail and the solar cells and skin on the upper surface of the wing to rip off. ).The distance between the neutral point (quarter chord point for an unswept wing) and the center of gravity is defining the amount of stability - if the c.g. Two wheels on each pod made up the fixed landing gear—rugged mountain bike wheels on the rear and smaller scooter wheels on the front. The investigation report identified a two-part root cause of the accident: This article contains material that originally came from the web article "Unmanned Aerial Vehicles" by Greg Goebel, which exists in the Public Domain. After a delayed take off, due to the failure of the winds to shift as predicted, Helios spent more time than expected flying through a zone of low-level turbulence on the lee side of Kauai, because it was climbing more slowly than normal, since it had to contend with cloud shadows and the resultant reduction in solar power. AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. NASA Langley Research Center Hampton, VA 23681 USA ... Helios Prototype (HP01), High-Altitude Configuration (1998-2002) ... the airfoil shape, and SunPower solar array. Transonic flow past Onera M6 wing (standalone and Helios) 3. Launch Date: 1974-12-10 Launch Vehicle: Titan IIIE-Centaur Launch Site: Cape Canaveral, United States Mass: 371.2 kg Funding Agencies. The Helios Prototype was the fourth and final aircraft developed as part of an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. The Pathfinder set a new altitude record for solar aviation in 1995, reaching over 50,000 feet. As a result of the persistent high dihedral, the aircraft became unstable in a very divergent pitch mode in which the airspeed excursions from the nominal flight speed about doubled every cycle of the oscillation. Helio-A; PL-741A; Helios 1; 07567; Facts in Brief. The aircraft impacted the ocean within the confines of the Pacific Missile Range Facility test range and was destroyed. Conversely, applying additional power to the motors in the center panels caused Helios to pitch up and begin climbing.[1]. ft. when flying at a gross weight of 1,600 lb. The electrically powered Helios was constructed mostly of composite materials such as carbon fiber, graphite epoxy, Kevlar, Styrofoam, and a thin, transparent plastic skin. "Helios Prototype Solar Aircraft Lost In Flight Mishap", NASA Pathfinder fact sheet, archived at archive.org, NASA Centurion Fact Sheet archived at archive.org, NASA's Helios Prototype Solar-Powered Aircraft, "3G Tested at 65,000 feet (20,000 m) in the stratosphere" 3G news release July 23, 2002, NASA-AeroVironment contract for followon projects, Commercial Orbital Transportation Services, https://en.wikipedia.org/w/index.php?title=AeroVironment_Helios_Prototype&oldid=1021522413, Unmanned aerial vehicles of the United States, 1990s United States experimental aircraft, Wikipedia articles incorporating text from NASA, Creative Commons Attribution-ShareAlike License, "Lack of adequate analysis methods led to an inaccurate risk assessment of the effects of configuration changes leading to an inappropriate decision to fly an aircraft configuration highly sensitive to disturbances. Frequently, the question arises as to what airfoil or airfoils were used in the wing design of a particular aircraft. There is extensive interest in High Altitude Long Endurance (HALE) unmanned air vehicles (UAV), used for atmospheric research, as pseudo-satellite systems, and for military C3I. From 2000 to 2001, the HP01 received a number of upgrades, including new avionics, high-altitude environmental control systems and SunPower solar array composed of more than 62,000 solar cells installed on the upper wing surface. It wa… The spar, which was thicker on the top and bottom to absorb the constant bending motions that occur during flight, was also wrapped with Nomex and Kevlar for additional strength. One of the primary concerns was a pair of wind shear zones off the island's coast. To turn the aircraft in flight, yaw control was applied using differential power on the motors — speeding up the motors on one outer wing panel while slowing down motors on the other outer panel. The Helios Prototype flying wing is shown near the Hawaiian islands of Niihau and Lehua during its first test flight on solar power from the U.S. Navy's Pacific Missile Range Facility.