The CT-4 Airtrainer was born out of two situations that occurred in the early 1970’s. Firstly the failure of the T6/24 Airtourer to meet the Royal Australian Air Force (RAAF) requirement for a basic trainer. Secondly the foresight of the AESL management of the time to exercise an already held option on the production rights to the Victa Aircruiser and adapt it into what we know as the CT-4 Airtrainer.

Development included a jettisonable clamshell canopy, revised seating and interior with side-by-side and optional third seat in the rear, and structural strengthening for aerobatic work. The wings are constructed separately, and during their installation to the fuselage are joined by splicing the two protruding main spars at 6 deg 4 min of dihedral on the top of the spar and 3 deg incidence at the root. Conventional control surfaces are utilised, with electrical spring bias trimming devices provided for the rudder and elevator and fixed tabs for the ailerons. Flaps are electrically operated and can be set at any position, while the fixed under¬carriage has a steerable nosewheel and the wheel brakes are toe operated.

Powered by a 210 hp Continental IO-360-H and the CT-4 was designed for aerobatics of +6 to -3g.

The first CT/4 Airtrainer s/n 001 first flew on 23 February 1972 (ZK-DGY).

The second prototype was built to refine the design. The second, c/n 002, was the only single-control model ever made. The two prototypes were the only Airtrainers made under the AESL banner.

AESL secured a RAAF contract to supply 37 aircraft. This order was followed by another from the Royal Thai Air Force for 24 aircraft.

These orders prompted the merger of AESL with Air Parts (NZ) Ltd and with the involvement of the New Zealand Government, New Zealand Aerospace Industries was formed.

The RAAF order followed the RTAF order down the production line also as CT-4As the first in December 1974 and continuing throughout 1975, ending with s/n 063.

A further order from a Swiss company named Breco had been secured for 14 aircraft (c/n 064 to c/n 077) and these immediately followed the last RAAF Aircraft down the line. These aircraft were designated CT-4B but were not the same as the civil CT-4Bs that were produced at a later date. They were in fact destined for Rhodesia (Zimbabwe) which was UN sanctioned at the time and the NZ Government prevented their export and consequently they were never delivered (although paid for).

The Royal New Zealand Air Force was next to sign up for CT-4s with an order for 13 aircraft. These were produced in 1976 ending with s/n 090. Although initially they were to be CT-4D models the aircraft were data plated as CT-4B, however technically they were neither as they were not built to the Type Certificate but to a RNZAF specification. The CT/4B designation described a higher all up weight requirement by the RNZAF to accommodate additional avionics.

Then the orders had run out and continuous production ceased at s/n 090.

When NZASIL announced the termination of CT-4 production the RNZAF in 1978 ordered a further 6 aircraft as attrition airframes.

In 1981 the RAAF, looking to expand their fleet of CT-4A Airtrainers, opted to purchase the Breco CT-4B aircraft that had been in storage since manufacture. These aircraft went down the production line once again retaining their original serial numbers to be converted from the Breco CT-4B specification into the RAAF CT-4A specification. The last aircraft was completed in May 1982 and that seemed to be it for CT-4 production.

With the purchase of NZAI by the Pacific Aerospace Corporation in 1982, the turbine project was taken out of the filing cabinet and re examined. Initially mooted was the CT4/CR featuring the Allison 250 B17 turboprop engine and a redesigned wing to accommodate a retractable undercarriage. Subsequently it was decided to build an intermediate stage, the fixed gear CT/4C.

With no airframes on hand to modify for the project, PAC approached the RNZAF and NZ1940 c/n 066, written off and reduced to spares was obtained. A 250 hp Allison turboprop, fitted with a PAC designed and built oil and fuel system to enable up to 30 seconds of inverted flight, was installed on 21 December 1990. Up front was a three bladed variable pitch Hartzell propeller.

On 21 January 1991 the CT/4C was test flown for the first time, by chief test pilot John Muir accompanied by Murray McGregor. Downrated to match the 210 hp of the CT/4B, the Allison was able to maintain its horse power through to 5000 feet. The CT/4C rotated at 60 knots and climbed away at 90 kts. The engine horsepower was increased to 300. At 300 hp John Muir described the aircraft as very quiet with more noise coming from the slipstream than the engine. Cruise on 300hp proves out at 165 knots (25 knots above the CT/4B on 75 percent power) and has a 2000 foot per minute climb rate at 105 knots. The stall is clean 58 knots, full flaps 48 knots. The engine uses about 80 litres/hour.

Production resurfaced under the PAC banner in 1990 when the RAAF decided to civilianise it’s basic training and sell off the majority of CT-4A Airtrainers.

In 1990, PAC proposed one major change to the new batch of Airtrainers; introducing an inverted oil system to permit extended inverted flight, a modification developed from the Christen system implemented by the RNZAF. The change is to be incorporated by Teledyne Continental at the factory level as the IO 360-HB9.

The contract to provide this training was awarded to BAe/Ansett in NSW (later BAe Systems Australia) who in 1990 ordered 12 CT-4 Airtrainers to undertake the task. These were produced from ex-RNZAF aircraft as civil CT-4B models during 1991 and 1992. The RTAF, aware that the CT-4 was back in production, placed an order for 6 CT-4B models and these were produced after the BAe/Ansett airframes taking total production to-date to 114.

During this same period the development of the CT-4E was undertaken in the hope of securing an USAF contract. Using ex Breco and ex RAAF airframe s/n 065 the development was successful, but the contract hopes not.

The CT/4E incorporates a larger engine and three-blade Hartzell prop. To compensate for the heavier 300 hp Textron Lycoming AEIO-540-L1B5 engine and Hartzell 3-blade variable pitch prop, the wings were located further forward. The first CT/4E flew on 16 November 1991 and entered production in 1998.

Pacific Aerospace CT-4E Air Test

In May 1992 production once again stopped.

Nothing further happened until 1996 when under the new Aeromotive ownership of PAC the Aeromotive Group was successful in securing a contract to lease of 13 CT-4E Airtrainers to the RNZAF as NZ1985 to NZ1997.

Production recommenced with a new serial number sequence for the CT-4E starting at s/n 200. The first CT/4E delivery to the RNZAF on 28 August 1998 and the last delivered in June 1999.

The RTAF placed an order for 12 CT-4E aircraft and these were produced during 1999 and 2000. In the middle of the RTAF order s/n 216 was reconfigured from RTAF specifications and is operated by Aerotec Flight Training in Queensland, Australia.

The RTAF ordered a further 4 CT-4Es and these were produced in 2001 followed in 2002 by 2 Aircraft for DSTA in Singapore.

All models were certified under NZ CTA A-10.

As of 2004 total production of the CT-4E had reached 32 (c/n 200 to c/n 231). In addition to 13 RNZAF and 16 Thai examples, one went to a private buyer in Israel and two to the Defence Science and Technology Agency Singapore.

Gallery

Production Data
CT-4 qty 2 s/n 001 – 002
S/n 001 was retained as a demonstrator and then eventually sold to a NZ syndicate.
S/n 002 was the only single control CT-4 ever built. It was gifted to the King of Siam (Thailand).
CT-4A qty 61 s/n 003 – 063
S/n 003 – 026 sold to RTAF
S/n 027 – 063 sold to RAAF (most on Australian civil register today. 3 in USA)
CT-4B qty 14 s/n 064 – 077
Not the same as a civil CT-4B model.
S/n 064 – 077 sold to Breco and never delivered. Converted to CT-4A model and sold to RAAF. S/n 065 owned by PAC as ZK-PAC (prototype CT-4E).
CT-4B qty 19 s/n 078 – 096
Not technically CT-4B although data plated as such.
S/n 078 -096 sold to RNZAF. Traded in on CT-4E models in mid 1990s. Converted by Aeromotive to civil CT-4B and most operated by BAe Systems Australia.
CT-4B qty 18 s/n 097 – 114
The only civil CT-4Bs ever produced.
S/n 097 – 108 sold to BAe/Ansett.
S/n 109- 114 sold to RTAF.
CT-4E qty 40 s/n 200 – 240
S/n 200 – 212 sold to Aeromotive (leased to RNZAF)
S/n 213 – not produced.
S/n 214 -215 sold to RTAF.
S/n 216 – sold privately in Israel.
S/n 217 – 230 sold to RTAF.
S/n 231 – 232 sold to DSTA Singapore.
S/n 233 – 240 sold to RTAF
S/n 241 – Company Demonstrator

CT-4 Model Development
CT-4C – Allison 250 powered Turbine variant developed but not certified on loan RNZAF s/n 088, returned to RNZAF as CT-4B.
CT-4CR – Allison 250 powered turbine variant with retractable undercarriage.
CT-4D – Original RNZAF model designation. Later revived as a Textron Lycoming TIO-360 powered variant.

Specifications:
CT-4

CT-4A
Engine: Teledyne Continental IO 360 H, 210 hp / 156.6 kW
Wingspan: 26 ft / 7.92 m
Length: 23 ft 2 in / 7.05 m
Height: 8 ft 5 in / 2.59 m
Empty weight: 1520 lb / 690 kg
Loaded weight: 2350 lb / 1070 kg
Max speed: 180 mph / 290 kph
Max range: 808 mi / 1300 km
Service ceiling: 17,900 ft / 5456 m

CT-4B
Engine: Teledyne Continental IO-360-H, 210 hp
Wing span: 26 ft (7.92m)
Length: 23.16 ft (2.59m)
Wing area: 129 sq.ft
Fuel cap: 320 lbs useable
Empty wt: 1699 lbs
MTOW: 2650 lbs
Max aerobatic wt: 2500 lbs
Vne: 207 kts
Maximum speed: 180 mph (290 kph)
VA: 141.5 kts
Stall: 58 kts
Cruise 65%: 150 mph
Endurance 65%: 4.86 hr
Maximum range: 808 miles (1300 km)
Useful load: 742 lb (337 kg)
ROC: 1350 fpm
Service Ceiling: 17,900 ft (5456 m)

CT-4C
Engine: Allison 250B17D turboprop

CT-4E
Engine: Lycoming AEIO-540L1-B5, 300 hp
Wing Span: 26.0 ft / 7.92 m
Area – Wing Gross: 129.0 sq.ft / 39.32 sq.m
Length Overall 23.48 ft / 7.16 m
Height (ground to top of fin): 8.50 ft / 2.59 m
Basic Empty Weight: 1780 lb / 807 kg
Max. Landing Weight: 2600 lb / 1180 kg
Stowage Capacity (Utility Category): 160 lb / 73 kg
Stowage Capacity (Aerobatic): 100 lb / 45 kg
Maximum Fuel: 322 lb / 150 kg
Fuel Capacity: 44 Imp Gal / 199 lt
Useable fuel: 198 lt
Fuel Consumption: 14 Imp Gal/hr / 65 lt/hr
Va Manoeuvring Speed: 144 kt
Vc Design Cruising Speed: 150 kt
Vd Design Diving Speed: 209 kt
Vs Stalling Speed – No Flap: 60 kt
Vsf Stalling Speed – With Full Flap: 45 kt
ROC 100 kt: 1500 fpm
Range: 520 nm / 836 km
Take off Ground Roll: 600 ft / 183 m
Landing Run: 553 ft / 168 m
Rate of Climb: 1830 fpm
Aerobatic Flight (Flaps Up): +6.0g / -3.0g
Wing Loading: 20.2 lb/sq.ft
Power Loading (at MAUW): 8.7 lb/hp
Area – Flap: 22.60 sq.ft / 6.89 sq.m
Area – Aileron: 11.56 sq.ft / 3.52 sq.m
Area – Elevator: 16.7 sq.ft / 5.09 sq.m
Area – Fin & Rudder: 12.69 sq.ft / 3.87 sq.m
Cabin, Inside Width: 3.64 ft / 1.10 m
Cabin, Inside Length: 8.93 ft / 2.72 m
Cabin, Inside Height: 3.83 ft / 1.17 m
Wheel Base: 5.45 ft / 1.66 m
Wheel Track: 9.75 ft / 2.97 m