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Piper PA-25 Pawnee

piper-pa25-235
PA25-235


The rapid expansion of Piper's operations in the 1950s meant that new facilities were soon required, and in 1957 the company opened a new aircraft development centre at Vero Beach, Florida, to be responsible for design, development and testing of new projects. The Vero Beach facility began its operations on a new specialised agricultural aircraft, designated Piper PA-25 Pawnee, for experience with the PA-18A configured for agricultural use had shown the active market for this category of aeroplane. Designed by Fred Weick and a development of a specialised ag-aeroplane called the AG-1, the Pawnee entered produc-tion in 1959 powered by the same 150 hp engine as in the Super Cub, Tri-Pacer and Apache.

A braced low-wing monoplane with fixed tailwheel landing gear, the PA-25 was powered initially by a 112kW Avco Lycoming O-320 flat-four engine, and this version was later redesignated PA-25-150 Pawnee. It had a glass-fibre chemical hopper installed forward of the cockpit, this having a volume of 0.57 cu.m, and the dust/spray distribution system was the same as that which had been proven on the PA-18A. Advanced design features were intended to reduce the likelihood of an accident and to give the pilot a far better chance of survival in a crash; thus he was given a high sitting position to ensure an excellent all-round view, above average strength seat restraints, and a specially designed structure that was installed to leave the cockpit substantially undamaged in the usual type of low-speed crash associated with agricultural dusting/spraying oprations.

 

PA25-160
PA25-160

 

In all, seven hundred and thirty-one Pawnee 150s, plus two prototypes, were built between 1957 and 1963. To improve the 150-hp Pawnee’s performance Airwork installed the larger Lycoming 0-360-A2A engine of 180 horsepower. On the advice of Civil Aviation of New Zealand, the Pawnee fuel system was rede-signed by Airwork and the fuel tanks situated far out in the wings. This mod proved to be excellent and no further troubles were encountered.

The 235 hp / 175kW Avco Lycoming O-540-B2B5 Pawnee with structural strengthening came on the market in 1962, including some with the more powerful 260 hp / 194kW O-540-E engine. Its hopper/ lank can carry 150 US gallons (568 litres) of liquid or 1,200 lb (544 kg) of dry chemi-cal, and it can be changed over from dus-ter to sprayer (or vice versa) in less than five minutes.

Some 235 hp models were converted by Airwork to have a 250 hp engine.

In 1965, Hazair at Orange modified a Pawnee 235 to incorporate side-by-side seating within he existing cockpit by widening the fuselage it several stations. A number of Pawnee 235s were converted in a similar fashion and other operators made comparable conversions.

The PA-25--235A/1 series was modified by widening the fuselage at the rear of the cockpit. Added to the top of the rear fuselage was the shaped turtledeck. The cockpit was fitted with dual controls and new side doors were "bulged" to provide more shoulder room. The hopper was removed and glider towing attachments and a release mecha-nism were fitted. Air Express was responsible for the conversion and the company had the aircraft certified in 5 June 1970. VH-KLA was then listed as a Piper PA-25-180A/1 and was re-registered to the Gliding Club of Victoria and Benella, Australia.

 

Piper-PA25-tow

 

A total of 5167 Pawnees of all types were built from 1959 to early 1982. Certification for the PA-25, 25-3 to 25-731, and all PA-25-235 was under FAA 2A10.

Derivatives:
Gippsland Aeronautics GA-200 Fatman

Specifications:

PA25-150
Engine: Ly-coming O-320

PA25-235
Engine: Ly-coming O-540-B2B5, 235 hp / 175kW
Prop: 7 ft 0 in (2.13 m) dia 2-blade
Wing span: 36 ft 2 in (11.02 m)
Length: 24 ft 8.5in (7.53 m)
Height: 2.21 m / 7 ft 3 in
Wing area: 183 sq ft (17.0 sq.m)
Gross weight: 2,900 lb (1,315 kg)
Empty weight: 725 kg / 1598 lb
Max cruising speed (duster/sprayer): 100/105 mph (161/169 kph)
Max range (duster/sprayer): 255/270 miles (410/434 km)
Accommodation: Crew 1

PA25-235D
Engines: Lycoming O-540-B2C5, 235 hp
Wing loading: 15.8 lb/sq.ft
Pwr loading: 12.3 lb/hp
Max TO wt: 2900 lb
Empty wt: 1420 lb
Equipped useful load: 1433 lb
Payload max fuel: 1202 lb
Range max fuel/ 75% pwr: 203 nm/ 2.1 hr
Service ceiling: 13,000 ft
Hopper cap: 150 USG
75% cruise: 99 kt
Working speed: 75 kt
Working endurance: 2.8 hr
Stall: 53 kt
ROC: 700 fpm
Min field length: 1350 ft
Fuel cap: 231 lb
Seats: 1

PA25-260 Pawnee C
Engine: 260 hp
Prop: CSU
Hopper cap: 145 USG

PA25-260D

Engines: Lycoming O-540-G1A, 260 hp
Seats: 1
Wing loading: 15.8 lb/sq.ft
Pwr loading: 11.2 lb/hp
Max TO wt: 2900 lb
Empty wt: 1472 lb
Equipped useful load: 1381 lb
Payload max fuel: 1150 lb
Range max fuel/ 75% pwr: 195 nm/ 2.0 hr
Service ceiling: 14,000 ft
Hopper cap: 150 USG
75% cruise: 100 kt
Working speed: 75 kt
Working endurance: 2.7 hr
Stall: 53 kt
ROC: 755 fpm
Min field length: 1250 ft
Fuel cap: 231 lb

piper-pa25-ld

Piper PA-25 Pawnee

 

 


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