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Murrayair MA-1

murrayma-1


The Murrayair MA-1, a conversion of the Stearman Kaydet, was designed by the technical services section of Air New Zealand at Mangere during 1968 and 1969. The conversion of the Stearman involved the fitting of a 600 hp P & W R-l340 Wasp engine from a Harvard to double the aircraft’s payload to 30 cwt, and the redesigning of the entire centre fuselage using a New Zealand-made integral fibreglass hopper. With a capacity of 62 cu ft it is the largest in the ag aviation industry. Fuselage panels are also of moulded fibreglass and are quickly removable for maintenance. An enclosed cockpit was also fitted. The rear fuselage, tail unit and strengthened undercarriage were from the Stearman. The wooden and fabric wings were increased in area by 35 per cent, and the entire strut system was redesigned to eliminate the flying and landing wires, using steel lift struts to accom-modate the increased gross weight (3,495 lbs to 6,250 lbs).

Work on the conversion of the Stearman began towards the end of 1968, and the first aircraft, N101MA, first flew from Mangere on July 27, 1969. The job was carried out for the Honolulu-based aviation service firm, Murrayair Ltd, which operated a fleet of modified Stearmans for spraying pineapple and sugar plantations in the Hawaiian Islands. By mid-1972 N101MA had flown 1,100 hours and production of five more pre-production aircraft, the MA-1, was begun. In 1974 the MA-1 was being produced at Harlingen in Texas by a subsidiary of Murrayair, Emair Ltd, at the rate of one aircraft per month, with completion of 2-3 aircraft per month planned by the middle of that year.

The Emair MA-1, was offered with a 1,200 hp Wright R-1820 engine derated to 900 hp. The MA-1B, which began its flight tests from Harlingen, Texas, in August, also has a new slower turning propellor with larger diameter and broader blades.

MA-1
Engine: P&W R-1340, 600 hp
Seats: 1-2
Wing loading: 15.7 lb/sq.ft
Pwr loading: 11.7 lb/hp
Max TO wt: 7000 lb
Empty wt: 3550 lb
Equipped useful load: 3398 lb
Payload max fuel: 2750 lb
Hopper cap: 450 USG / 30 cwt / 62 cu.ft
75% cruise: 95 kt
Working speed: 90 kt
Working endurance: 2.9 hr
Stall: 56 kt
Fuel cap: 648 lb

MA-1B
Engine: Wright  R-1820, 900 hp
Seats: 1-2
Wing loading: 15.7 lb/sq.ft
Pwr loading: 8.9 lb/hp
Max TO wt: 8000 lb
Empty wt: 4300 lb
Equipped useful load: 3648 lb
Payload max fuel: 3000 lb
Hopper cap: 450 USG
75% cruise: 115 kt
Working speed: 105 kt
Working endurance: 2.3 hr
Stall: 63 kt
ROC: 1750 fpm
Min field length: 1600 ft
Fuel cap: 648 lb

 

 


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