Ryan XV-5
| Ryan XV-5 | |
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| Type: | Experimental V / STOL aircraft |
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2 |
The Ryan XV-5 is a jet-powered V / STOL aircraft made by the US manufacturer Ryan in the 1960s. Until 1962 , the US Army referred to the design as VZ-11 .
history
Development of the lift fan concept
General Electric (GE) and Ryan, along with other manufacturers, began studies on gas-powered fan-in-wing systems in the mid-1950s. The USAF also carried out corresponding studies in 1956, but it was not until 1957 that a practical implementation could be tackled for the first time with funds from the US Army Transportation Research Command (TRECOM). At that time, GE had begun testing scaled-down model systems at its main facility in Evendale, near Cincinnati , to find the best shape for the fan inlet spiral to deliver the gas to the blade tips. As a result of the trials, GE eventually selected a fan 5 feet in diameter and connected it to a J85 engine. Later a small bow fan followed and then a second fan with a powerplant. Each engine could flow to each fan via corresponding jet distributors, so that in the event of failure of one engine, the remaining one could still drive all three fans and generate around 60% of the maximum lift force. However, the power of one engine would not have been sufficient to prevent a hard landing. The tests ran for 340 operating hours.
In 1957, Ryan also received an order from the USAF to create an "engineering study" on the possibilities of using the lift fan drive system in different aircraft designs. In addition to a supersonic fighter, transport aircraft with an all-up weight between 15,000 and 55,000 kg were also examined. However, once the study was complete, the USAF put it on file and turned to the TFX program instead.
GE discussed the application of its fan system, known as the X353, with a number of aircraft manufacturers. Most used a 5 ft. Diameter (X353-5) wing fan for their proposals. One of the concepts presented was the Republic AP-100 with a design like the later F-15. The tactical fighter was to use a total of six J85 engines and three X353-5 fans. A maximum speed of Mach 2 was planned in level flight. However, with the technological possibilities of the time, this goal could not be achieved directly. Therefore, a simple test aircraft should first be built to test the system.
Construction of the XV-5A
General Electric and Ryan participated in the US Army tender for a VTOL surveillance aircraft and competed against the Lockheed XV-4 (Lockheed Model 330) and Hawker Kestrel (XV-6A). In November 1961, General Electric won the competition to design, build, and test the US Army lift fan test aircraft XV-5A. Ryan was designated as a subcontractor for this order from TRECOM. Republic Aviation was to be involved in the flight test, NASA provided its wind tunnel and the USAF the J85 engines and diverter valves .
On November 15, 1961, GE signed a contract with the US Army to supply two VZ-11 V / STOL test aircraft. Since GE did not manufacture aircraft, Ryan was hired to do this, with Republic assisting with flight testing. NASA was scheduled for wind tunnel studies at the Langley Research Center in Virginia and the Ames Research Center in California.
The first XV-5A (1962 was a general renaming of the aircraft of the US armed forces in a uniform system) had its rollout on February 26, 1964. The machine carried the USAF serial number 62-4505. Lou Everett made the first conventional flight on May 26, 1964 at Edwards AFB, followed by the first hover on July 16, 1964 and the first transition from horizontal to hover on November 6 of the same year. In January 1965, the US Army Aviation Materiel Laboratories at Fort Eustis accepted the two machines.
testing
At the end of test phase I, speeds of up to 525 mph at 8000 ft. And in fan-assisted mode up to 103 mph began. In February 1965, test phase II began, with one on April 27, 1965 during the first public demonstration of the XV-5 inadvertent shutdown of the fans at low altitude at low speed by the pilot. The pilot Everett was still able to use the ejection seat, but did not survive the crash. The plane was completely destroyed.
After that, simulations of military missions were flown for the first time with the remaining machine. After a subsequent four-month conversion phase, it was possible for the first time to drive the fan with a jet engine and to use the other engine only with horizontal thrust at the same time. In October 1966, the first attempts to use the XV-5 in the SER (Strike Escort Rescue) area, today mostly referred to as Combat Search and Rescue , began. During one exercise, the lifeline got caught in a fan that was slowed down hard, after which the machine hit the ground hard. The probably inadvertently triggered rejection of the ejection seat, which was not equipped with zero-zero capabilities , led to the death of the pilot.
However, the aircraft was able to be repaired and was handed over to NASA in March 1967 as the XV-5B. A complete renovation followed in May, with a new wing with a modified profile, larger area and lower resistance, as well as a more efficient fan installation being installed. In addition, the retractable landing gear used until then was replaced by a fixed version with a much wider track width, and the previous color scheme in army olive green gave way to the white NASA standard paint. NASA carried out the first levitation tests in August 1968 at the Ames Research Center . Flight tests were carried out until 1974.
In summary, the transition from hovering to flying was difficult and sudden. The lift system was too heavy and took up too much internal volume, so this concept was not pursued any further. The XV-5 was one of the last aircraft to be developed by Ryan.
construction
Technical and physical background
The use of jet engines as lift engines is greatly restricted by high kerosene consumption and great noise development. GE planned a system that, instead of the fast, hot exhaust jet of a jet engine, would generate a much larger but slower and cold mass flow for vertical take-off and landing. This would significantly reduce both noise and fuel consumption. With a given lift force, it would be possible to install a smaller engine compared to a jet drive.
The lift fan concept is comparable with the turbofan engines developed since the 1970s, which also divert part of their power in order to generate a large mass flow via an upstream fan and thus greatly increase the effective thrust of the engine. Instead, GE used the exhaust gas jet to drive the fan and guided it over the fan blade tips and set it in rotation at a maximum speed of 2649 min −1 .
A military VTOL aircraft equipped with this system should therefore be able to function as a rescue aircraft for crashed crews without endangering the people to be captured by a hot exhaust jet and then leaving the enemy area at high speed. The concept also appeared to be very suitable for other military applications, such as close air support and reconnaissance up to Mach 2 speed range.
Technology of the lift fan concept
The buoyancy system consists of the individual components turbojet, jet deflector, nozzle outlet, inlet spiral for the fan ( scroll ), movable fan inlet flaps and adjustable outlet baffles, similar to a blind. The actual fan has 36 long blades, which are connected to one another at the edge with a ring. This ring finally carries the actual 324 turbine blades on the outer edge. The fan blades had a diameter of 1.93 m and were responsible for the main lift (air throughput of 242 kg / s) as well as for the roll and yaw control, which was realized by movable outlet flaps on the underside. The third (front) lifting fan (0.9 m) was located in front of the cockpit and was mainly responsible for pitch control.
When hovering, the jet deflector directs the exhaust gas jet over the turbine blades. The inlet flaps of the blower are open and the outlet baffles are vertical. During the transition process, the outlet plates direct the blower jet backwards, generating both vertical lift and horizontal propulsion. As soon as the stall speed is exceeded, the jet deflector is closed and the exhaust jet from the turbojet engine leaves the aircraft via the nozzle outlet. The inlet flaps of the blower are then closed and the aircraft flies like a conventional jet aircraft until it lands, after which the entire sequence is reversed. The system itself was controlled with a conventional control with sticks and pedals and an additional lift control lever similar to that of a helicopter.
Each fan generated about three times the thrust of the gas generator as a buoyancy force. The two J85s together delivered 5316 lbf of thrust through the gas generators, while the two lift fans in the wings generated 14,500 lbf of lift and the fan in the nose fuselage generated 2500 lbf, making for an aircraft with a target total weight of 9200 lbf safe hovering should be possible. The lifting fans in each wing, which can be closed by two flaps, were designated as X353-A and the lifting fan in the aircraft nose was designated as X376.
Airframe
The XV-5 had a two-man cockpit with ejection seats arranged side by side and was designed as a middle-decker with a T-tail unit . The fuselage, on the back of which was the air intake, consisted of a simple structure with ribs and tubular trusses. The required performance data were similar to those of the Douglas A-4 Skyhawk.
Technical specifications
| Parameter | Data |
|---|---|
| crew | 2 |
| length | 13.56 m |
| span | 9.09 m |
| Diameter front fan | 0.9 m |
| Diameter wing fan | 1.93 m |
| height | 4.50 m |
| Empty mass | 3175 kg |
| Max. Takeoff mass | 5663 kg |
| Top speed | 845 km / h |
| Engines | 2 × J85-GE-5 turbo jets each with 11.47 kN thrust in flight and 33.02 kN each in hover (designation of the fan system for vertical flight: X535-5) |
Whereabouts
The Ryan XV-5B is owned by the United States Army Aviation Museum at Fort Rucker, Ozark ( Alabama ).
See also
literature
- Daniel J. March: VTOL flat-risers - Lockheed XV-4 and Ryan / GE XV-5 (Pioneers & Prototypes) . In: International Air Power Review. Volume 16, 2005, pp. 118-127.
- Bill Gunston: Ryan XV-5 Vertifan . In: Airplane Monthly. June 1977, pp. 290-296.
- John WR Taylor (Ed.): Jane's All The World's Aircraft - 1965-66 , Sampson Low, Marston & Company Ltd., London, 1965, pp. 297 f.
- William T. Immenschuh: V / STOL by Vertifan . In: Flight. October 1, 1964, pp. 595-598, online (accessed August 14, 2014).
- Robert H. Goldsmith, David H. Hickey: Characteristics of Aircraft with Lifting Fan Systems for V / STOL, Part 1 (Aerospace Technology) . In: Flight Revue. October 1963, pp. 23-28.
- Robert H. Goldsmith, David H. Hickey: Characteristics of Aircraft with Lifting Fan System for V / STOL, Part 2 (Aerospace Technology) . In: Flight Revue. November 1963, pp. 23-28
- Ryan VZ-11 - whiz kid for the US Army . In: Flug-Revue. November 1962, p. 56
Web links
- FLIGHT article, September 27, 1962 (accessed August 13, 2014)
- GlobalSecurity.org
- Ryan Aeronautical Corporation commercial
- Editing of recordings of various tests with the prototypes: Part 1 , Part 2
Individual evidence
- ↑ FlugRevue December 2008, pp. 100-103, Schwebewunder - Ryan XV-5 Vertifan