I.Ae. 24 Calquin

I.Ae. 24 Calquin
I.Ae.24 Calquin in squadron use, c.1950
Role	Light Bomber
Manufacturer	Fabrica Militar de Aviones (FMA)
Designer	Juan San Martin
First flight	4 July 1946
Retired	1960
Primary user	Fuerza Aérea Argentina
Produced	1947-1950
Number built	101

The I.Ae.24 Calquin (a Mapudungun word which means "Royal Eagle") was a tactical bomber designed and built by the Instituto Aerotécnico (Córdoba) in Argentina in the immediate post-World War II era. Although superficially a "look-alike" for the de Havilland Mosquito, the I.Ae.24 was powered by twin Pratt & Whitney R-1830-G “Twin Wasp” radials giving it a distinct appearance. After an operational career spanning two decades, the Calquin was retired.

Design and development

Patterned after the successful de Havilland Mosquito, the Calquín had a wooden structure similar to the FMA AeMB.2, and was the first twin-engined aircraft designed and built in Argentina. The I.Ae.24 design was based on a cantilever mid-mounted wooden (indigenous woods were used throughout) wings with fabric-covered flying surfaces. The conventional main twin-oleo undercarriage retracted into the engine nacelles while the tailwheel retracted into the aft fuselage. The two-man crew were seated side-by-side under a large transparency constructed partly of acrylic glass with glass panels. The armament consisted of four 12.7 mm machine guns grouped in the nose. Some examples later had four 20 mm cannons and an internal bombload of 1,764 lb (800 kg) kg along with 12 rockets (75 mm) mounted under the wings.

Originally the I.Ae. 24 was also intended to be equipped with Rolls-Royce Merlins but an adequate supply of the powerplants was not possible, consequently Pratt & Whitney R-1830-G “Twin Wasp” radials of 1,050 hp (782.5 kW) were substituted. Performance estimates of a Merlin-powered variant would have made it comparable to the Mosquito but the R-1830-powered prototype was able to achieve only 273 mph (440 km/h), making the aircraft unstable and prone to stalling. A later prototype, the I.Ae.28 was equipped with Rolls-Royce Merlins but the project was superseded by the more capable I.Ae. 30 "Ñancú".

Operational history

Despite the lower performance obtained in testing, the I.Ae.24 Calquin was able to undertake an attack and light bombing role, replacing the Northrop A-17 in the Argentine Air Force inventory. A total of 100 aircraft were ordered, with the first production example flying on 4 July 1946. Fifty pilots and crew members were killed in accidents related to Calquín operational service and trials. Test pilots considered the aircraft unstable "on all three axes" and required careful handling. Series production was completed by 1950, with operational service continuing until 1957 although a small number of aircraft were still in squadron use until 1960.

Operators

Argentina

• Argentine Air Force

Specifications (I.Ae.24 "Calquín")

Data from Jane's Encyclopedia of Aviation

General characteristics

• Crew: two: pilot, bombardier/navigator
• Length: 39 ft 4.5 in (12 m)
• Wingspan: 53 ft 5.75 in (16.3 m)
• Height: 17 ft 5 in (5.3 m)
• Max. takeoff weight: 15,873 lb (7,200 kg)
• Powerplant: 2 × Pratt & Whitney R-1830-G "Twin Wasp" 14-cylinder air-cooled radial engine, 1,050 hp (782.5 kW) each
• Propellers: Three bladed Hamilton Standard Hydromatic 23-E-50 propellor

Performance

• Maximum speed: 440 km/h (273 mph, 237 knots)
• Range: 1,040 km (646 mi, 562 NM)
• Service ceiling: 10,000 m (32,800 ft)

Armament

• 4× 20 mm Hispano Mk II cannon
• 4× .303 in (7.7 mm) Browning machine guns
• 12 x 60 lb (27 kg) rockets (Mk VI)
• 1,764 lb (800 kg) bombs

See also

Comparable aircraft

• de Havilland Mosquito

References

Bibliography

• Baldini, Atilio and Sergio Bontti. I.Aé.- 24 Calquin (in Spanish). Buenos Aires: Jorge Nunez Padin, 2007. ISBN 978-987-20557-1-4.
• Burzaco, Ricardo. "I.Ae. 24 Calquin." Aeroespacio, Nro. 52, November–December 1997.
• Burzaco, Ricardo. Las Alas de Perón: Aeronaútica Argentina 1945/1960 (Spanish). New York: Ed. Da Vinci, 1995. ISBN 978-987-96764-4-8.
• Janes's All the World's Aircraft 1957-1958. London: Jane's All the World's Aircraft, 1958.
• Taylor, John W. R., and Jean Alexander.Combat Aircraft of the World. New York: G.P. Putnam's Sons, 1969. ISBN 0-71810-564-8.
• Taylor, Michael J.H. Janes's Encyclopedia of Aviation, Vol. 4. Danbury, Connecticut: Grolier Educational Corporation, 1980. ISBN 0-7106-0710-5.

External links

• I.Ae.24 "Calquin" (in Polish)
• I.Ae.24 "Calquin" (translated into English from Spanish)
• Aircraft history and specifications (in Spanish)
• Aircraft history, specifications and colour images (in Spanish)
• Pre-series testing by the "Grupo Experimental de Vuelo" (in Spanish)