Mississippi State University XV-11
| Mississippi State University XV-11A Marvel | |
|---|---|
 Marvel ii |
|
| Type: | Experimental airplane |
| Design country: | |
| Manufacturer: | |
| First flight: |
December 1, 1965 |
| Number of pieces: |
1 |
The Mississippi State University XV-11A Marvel (internal university description MA-17) was an American STOL - experimental aircraft from the 1960s.
history
background
The origins of the development of the Marvel go back to 1950 when the Office of Naval Research awarded a research contract to the Aerophysics Department of Mississippi State University (MSU) to investigate the field of boundary layer effects on wings . The investigations lasted until 1962, after which the US Army Transportation Research Command took over and continued them. The subject of the project was investigations with a boundary layer suction through thousands of small holes distributed over the wing, in addition, the combined effect of changes in the profile curvature and the use of a ducted propeller played an important role. Initially, the university used a number of different aircraft for the research program, such as a Swiss TG-3A glider (approval N64907), a Piper YL-21 (USAF serial number 51-6496) and a Cessna L-19 A (51-11972).
It turned out, however, that the aircraft used should ideally have a pusher propeller that does not generate a slip stream that interacts with the flow over the wing . The Anderson Greenwood AG-14 , a single-engine machine with double tail booms and a pusher propeller, was regarded as the only aircraft suitable for this purpose . On June 27, 1955, the MSU therefore procured the fourth of a total of six AG-14 (N3903K) produced, which then received a casing for the pusher propeller. In this configuration, 20 flight hours were completed, but then sold again because no certificate of airworthiness ( airworthiness certificate could be obtained).
Marvel
In the meantime, a completely new wing construction was seen as necessary in order to achieve a complete influence on the boundary layer and the profile curvature. In addition, the use of GRP for the wing was considered to be mandatory in order to keep the surface unevenness as small as possible. With these specifications, the Mississippi Aerophysics Research Vehicle Extended Latitude, briefly designated with the acronym MARVEL, was created and the Mississippi Aerophysics Study No. MA-17 wore.
It quickly became clear, however, that the suitability of the planned machine for the intended investigations had to be proven in advance using a smaller and weaker test machine. For this purpose, the Marvelette (diminutive of Marvel) was built on the basis of the fourth AG-14 (N3901K) produced and flown for the first time on November 16, 1962. The test flights were continued until March 1964, with landing speeds of 56 km / h and a top speed of 200 km / h.
The Marvel's maiden flight took place on December 1, 1965. The machine was given the USAF / Army serial number 65-13070. The flight test program initially comprised 49 flights with a duration of 35 hours, which were completed by April 1967. These flights showed a disappointing effect of the boundary layer influencing, since the suction speeds through the wing were not high enough to prevent a flow separation, especially with arches over 10 degrees. The increase in lift was very small. Up to the expiry of the formal US Army contract, 100 flight hours had been completed, with maximum speeds of 330 km / h and minimum take-off distances of 38 m.
Marvel ii
The aircraft was then decommissioned until 1981 when the company Biroc Ltd. from Arlington, Virginia placed an order with MSU for a concept study for a multipurpose desert aircraft. The desired results were the applicability on soft sand slopes , a low infrared signature and low radar reflection .
The necessary modifications to the Marvel mainly concerned the wings, which were newly made with a Kevlar skin . The engine was also exchanged for an improved T63 version, which now delivered 420 hp. The propeller was now also made of Kevlar. The aircraft was re-registered as the N2768Q on June 11, 1982 and is now referred to as the Marvel II. After 21 flights in the USA, the ship was shipped to Saudi Arabia , where the first flight took place on November 15, 1982 in Taif . After only two flights, the Marvel II was transported back to the USA, as it turned out that the set research goals could not be achieved. Between 1987 and 1989, flights were still occasionally carried out, including at air shows.
construction
The Marvel was built almost entirely from fiberglass materials, only for reinforcement individual components were made of steel, especially in the area of the Allison T63 turboprop engine . For gluing the GRP parts were epoxy resins and as a filler polyurethane used foam. The GRP spar had individual layers of steel for stiffening, otherwise the wings were made entirely of GRP. The curvature could be changed by up to 30 degrees with a special electrically driven wing warping mechanism, which extended over half the span.
To generate the negative pressure for influencing the boundary layer, the installation of an auxiliary unit Solar T62 was originally planned, but in the practical implementation the compressor was driven by the main engine. Elevator and rudder were also integrated into the casing of the propeller, with the elevator sticking out over the edge of the casing. The Allison T63 turbine was installed in a steel box, which also provided the necessary fire barrier. The power was transmitted to a reduction gear and a constant-speed propeller via a 2.10 m long long-distance shaft .
The air for the engine was fed in through the air sucked in from the boundary layer control and through small inlets on the leading edge of the wing. The chassis had an unusual design with four wheels, each of which was arranged in tandem in a kind of runner. The front wheel was always controllable. This arrangement, called pantabase , should ensure good take-off and landing properties on soft ground. The look was reminiscent of the construction Vincent Burnelli chose for his Uppercu-Burnelli GX-3 in the late 1920s.
Technical specifications
| Parameter | Marvel | Marvel ii |
|---|---|---|
| crew | Max. 2 | |
| Passengers | Max. 2 | |
| length | 7.08 m | |
| span | 7.99 m | 11.24 m |
| height | 2.59 m | |
| Wing area | 9.84 m² | 14.69 m² |
| Wing extension | 6.48 | |
| profile | NACA 63615 (modified) | |
| Empty mass | 888 kg | |
| Max. Takeoff mass | 1188 kg | |
| Top speed | 330 km / h | |
| Engines | an Allison T63 -A-5 turboprop engine with 250 WPS (187 kW) | an Allison T63 with 420 WPS (313 kW) |
See also
literature
- Jos. Heyman: The Mississippi Marvel. in Air Enthusiast, Forty-one, 1990. Bromley, UK: Tri-Service Press. ISSN 0143-5450 .
- Wolfgang Luber: XV-11A Marvel - Interesting STOL test aircraft from the USA. in Flug, Revue September 1968, p. 26 ff.
Web links
Individual evidence
- ↑ TECHNICAL REPORT 67-21, p. 26.
- ↑ Landing gear of the GX-3 (1929)