Acrostar | |
---|---|
| |
Role | Aerobatic aircraft |
National origin | West Germany |
Manufacturer | Wolf Hirth GmbH |
Designer | Arnold Wagner |
First flight | 16 April 1970 |
Number built | 10 |
The Hirth Hi 27 Acrostar was designed by Arnold Wagner to win aerobatic competitions, in part by having handling independent of orientation, upright or inverted. A single engine, single seat low-wing monoplane, it was built in West Germany by Wolf Hirth GmbH in the early 1970s, and dominated Championships for a brief period.
The Hirth Hi 27 Acrostar is a competition aerobatic aircraft designed by the Swiss aerobatic champion, Arnold Wagner. Wagner and three others, two of them German ex-champions, sponsored the construction. The Wolf Hirth team was led by Prof. Richard Eppler of the Stuttgart Technische Hochschule, starting work in the Summer of 1969. The first flight of what was known as the Acrostar Mk II was on 16 April 1970. [1]
The Acrostar is a conventionally arranged low wing single engine aircraft. The wing is straight tapered, the leading edge slightly swept and the trailing edge unswept. The aerofoil section, designed by Eppler, is quite thick with a thickness-to-chord ratio of 20%. It is a symmetric section and mounted at zero incidence. There is also zero dihedral. Full span control surfaces are fitted, flaps inboard and proportionally moving ailerons outboard. The ailerons are balanced not by the usual horn or hinge line extensions but by small surfaces which project beyond the wingtips. Unusually, both ailerons and flaps are coupled to the elevator position; this camber changing control system, together with the highly symmetric wing, produces the same control characteristics for normal and inverted manoeuvres. The basic idea in this arrangement was to keep the centerline of the fuselage horizontal in both normal and inverted horizontal flight. The result, beside this, is good controllability in low speed ballistic flight, around zero G.
Another unusual control feature, allowing for independent trimming in pitch and yaw, are the independent trim tabs on the flaps. [1]
The plywood covered wing is built around a single glass fibre spar using foam reinforced ribs. Aft of the engine, the fuselage is a wooden semi-monocoque. The single seat cockpit is enclosed with a rearward sliding canopy. The fin and balanced rudder are straight tapered and square tipped, as is the rearward set horizontal tail. The prototype had elevator trim tabs but these were removed in favour of the flap trims noted above. Extra fin area is provided by a long strake on the lower fuselage, extending aft to the tailwheel. [1]
The Acrostar is powered by a 220 hp (165 kW) Franklin 6A-350-C1 six cylinder horizontally opposed piston engine. This is mounted in a steel frame which is integral with the fixed cantilever main undercarriage and its optionally streamlined, tapering legs and faired wheels. This arrangement places the main landing gear further forward than usual, [1] providing a drag moment to oppose that of the fin in vertical flight. [2] The tailwheel is steerable. [3]
The first prototype D-EMKB appeared in competition, three months after its first flight, at the 1970 6th World Aerobatics Competition [2] at Hullavington, England [1] where it was placed 4th on the individual men's list. [4] Nonetheless, it made a strong impression [5] and attracted orders from Germany, Switzerland and Spain [6] for participation in the 1971 European and 1972 World Championships. Acrostars gained 1st and 3rd places at the former, the Trophée Biancotto held at Carcassonne, France. [7] By January 1972 four had been built and another five were due for delivery ahead of the 7th World Championship, [1] held in Salon-de-Provence, France in July 1972. Four participated with Swiss pilots coming 4th and 8th, bringing their team in 3rd place behind the US and USSR. [8] During 1973 Acrostars won first place in the Coupe Champion Amberieu in France, the Scandinavian Cup, the Swiss International Championships, the West German Championships and the Zadar Cup in Yugoslavia. [3]
In all 9 Acrostar Mk IIs were built. [6] The sole Mk III weighs less and has performance and handling improvements. These include lightened control surfaces and refined wing root fairings. It also has engine cooling and lubrication changes to allow glider towing without overheating (Mk III remained a project). [3] The Acrostar prototype D-EMKB remained active until at least June 2009. [9] The third Acrostar, F-AZJF, previously HB-MSA was undergoing restoration in early 2010 [10] and EC-CBS has been on display in the Museo de Aeronautica Y Astronautica, Cuatro Vientos, Madrid. [11] Serial number 4009, originally D-EOIG, now HB-MSK, is since 1980 in private ownership, based at Donaueschingen, Germany.
Data from Jane's All the World's Aircraft 1975-6 [12]
General characteristics
Performance
The Schempp-Hirth Discus is a Standard Class glider designed by Schempp-Hirth. It was produced in Germany between 1984 and 1995 but has continued in production in the Czech Republic. It replaced the Standard Cirrus. It was designed by Klaus Holighaus.
The VEF I-12 was a tandem, two seats Latvian trainer aircraft designed by Kārlis Irbītis and produced by VEF in Riga.
The Civil Aviation Department Revathi was a light utility aircraft designed in India principally for use by that country's flying clubs.
The Lemberger LD20b was a single-engine cantilever biplane designed to be easily towable behind a car. Built in Germany in 1971, it made several flights but did not enter production.
The Dyn'Aéro CR.100 is a French kit built single engine, two-seat monoplane, developed in the 1990s and intended as both an aerobatic trainer and a tourer, primarily for aero club use.
The Aeronix Airelle is a tandem wing ultralight with twin engines in push-pull configuration, that was designed and built in France at the start of the millennium. It was intended to be homebuilt from kits, and a few prototypes were constructed, but development ended when the company went into receivership in 2006.
The Stolp-Adams SA-100 Starduster is an American single-seat sport biplane designed to be built from plans supplied by Aircraft Spruce & Specialty Co. Though the first flight was in 1957, Stardusters continue to be built and flown.
The Howland H-2 Honey Bee is an American homebuilt aircraft that was designed by Bert Howland and made available by Howland Aero Design in the form of plans for amateur construction, with kits provided by Aircraft Spruce & Specialty Co. The H-2 first flew in 1986.
The Timm T-840 was a twin engine, high wing passenger aircraft designed and flown in the United States in 1938. Equipped with a tricycle undercarriage and low speed aerodynamic devices, it could be configured to carry between six and ten passengers. Only one was built.
The Cijan-Obad Orao is a competition single seat sailplane designed in Yugoslavia just after World War II, one of the most advanced of its type at the time. It flew in three World Gliding Championships, having greatest success at its first in 1950 when it reached third place.
The Pasotti F.9 Sparviero was a four-seat, low-wing touring aircraft, built in Italy in the 1950s. Designed by Stelio Frati, it was a single-engine version of his earlier twin-engined Airone. Only one was built.
The Starck AS-57 is a single engine low wing monoplane seating two in side-by-side configuration. It was designed and built in France just after World War II; only ten were produced, one of which was still active in 2012.
The SZD-42 Jantar 2 is a single seat Open Class competition glider, designed and produced in Poland in the 1970s. It features a span of over 20 m (66 ft) and elastic, camber changing flaps. It was placed second, third and seventh at the 1976 World Gliding Championships. Over one hundred were built and more than ninety remain registered.
The Stephens Akro is a single engine monoplane designed in the United States for aerobatic competitions. It first flew in 1967 and proved very successful, leading to several developments of which one won seven US Championships and one World Championship between 1975 and 1982. The Extra EA-230 and Extra EA-300 were also Akro developments with over two hundred built.
The Speedtwin E2E Comet 1, originally named the Phillips ST1 Speedtwin, is a two-seat, twin engined aircraft designed in the UK to be capable of aerobatics and the only civil twin certified for intentional spinning. After a long development time, just two have been built.
The Caudron C.580 was a French advanced trainer aircraft intended to prepare pilots for the new low wing monoplane fighters of the mid-1930s. It did not go into production and only two were built.
The Lambert Twin Monocoach was a light, twin-engined U.S. aircraft, designed to carry three or four passengers. Initially it was fitted with economical, low-powered engines but even given a large increase of power it failed to attract customers.
The Möller Stomo 3 was a small, low-powered but very aerodynamically-clean light aircraft, first flown in Germany in 1939. It set two speed over distance records for aircraft with engines of less than 2 l (120 cu in) capacity soon after its first flight.
The MIP Smyk, MIP from the initials of its Polish designers with Smyk meaning Brat or Kid, was an aerodynamically refined motor glider designed and built at Warsaw Technical University from 1935.
The Alcor Junior was a small, six passenger, twin-engined airliner built in the U.S. and flown in 1938. As on Alcor's earlier Duo-4 and Duo-6, its inline engines were mounted horizontally to minimize their separation and drag. Only one was built; it was lost in a crash less than four months after its first flight.