Beechcraft 90 King Air / U-21 / VC-6 / T-44 Pegasus
Beech had been working on the model 90 King Air since 1963 (then identified as the Beech Queen Air Model 65-80) utilising the 373kW P&W turboprop PT6 engines. This aircraft was basically a Queen Air fitted with turboprop engines and first flew in January 1964. It proved to be faster than the Twin Otter but still only provided seating for nine pas-sengers. The Model 65-80 designation was confusing as there were Model 65 and Model 80 Queen Airs in production, so the aircraft became known temporarily as the Model 65-90T (T standing for turboprop). In due course, an even better job was made of clarifying the situation by renaming the turboprop-powered Queen Airs as King Airs. In effect, therefore, the Model 65-90T was the prototype for the Beech Model 90 King Air series, but more specifically became the prototype of the unpressurised military Kings Airs.
Following the first flight of the Model 65-90T, a civil equivalent was produced in parallel with a pressurised cabin, and the first production prototype of this aircraft, designated Model 90 King Air, flew for the first time on 20 January 1964.
US Army testing of the Model 65-90T, under the military designation NU-8F, had shown the aircraft to be suitable for the military requirement, so an initial order for 48 aircraft, under the designation U-21A (TC 3A20), was placed. Beech distinguished its military King Airs from civil versions by identifying them as Model 65-A90-1, and began modification of the civil aircraft to provide a utility interior. This accommodates a crew of two and 10 troops, or six to eight command personnel, or three stretchers, and seating can be removed easily for the carriage of up to 1361kg of cargo.
Initial deliveries of production U-21As, which were given the name Ute, began on 16 May 1967, and subsequent contracts resulted in more than 160 being built. These included U-21As and RU-21A/RU-21D variants all with 410kW Pratt & Whitney PT6A-20 turboprops, and RU-21B/ RU-21C/RU-21E variants with 462kW PT6A-29s. The RU-21s were developed especially for operation in an electronic reconnaissance role in South-East Asia, sprouting a strange collection of aerials and sensors, and being equipped internally with related avionics' systems, plus nav/com systems suitable for all-weather operations. RU-21Bs and RU-21Cs had Beech designations Model 65-A90-2 and Model 65-A90-3 respectively, and the designation U-21G applied to 17 aircraft for the USAF that were similar to the U-21A. Deliveries of the civil Model 90 King Air began in late 1964, this having cabin pressurisation, and accommodating a maximum of 10 persons, including the pilot. It was superseded in early 1966 by the King Air A90, which introduced the more powerful PT6A-20 engines.
The 90, A90 (first flying in 1966) and B90 are all powered by 500 shp.
The A90 was followed by a King Air B90 with detail improvements in 1970, the B90 was fitted with a 550-shp Pratt & Whitney engines.
In September 1970 by the King Air C90 which introduced a more advanced pressurisation and heating system for the cabin, still with 550-shp Pratt & Whitney engines. The C90 was in production in 1982, with a total close to 1,000 having been delivered by the end of the year. One of these, designated VC-6B, also serves with the USAF's 1,254th SAM Squadron. The single VC-6A operated by the 89th Military Airlift Wing at Andrews AFB, Maryland, was placed in service in early 1966, and retired in 1985.
Since its introduction, the C90 has been the subject of steady improvement, the 1982 powerplant was the PT6A-21. Ten examples of the C90 serve with the Spanish air force and civil aviation school for instrument training and liaison.
The E90 became part of the lineup in 1972 and employed the 680-shp Pratt & Whitney PT6A-28 turboprop, flat-rated to 410kW. All have full-feathering, reversible propellers. Their pressurized, three-compartment interior can be maintained at sea level atniosphere pressure to flight levels as high as 10,500 feet. The E90 is virtually a more powerful version of the C90. This version remains in production in 1990.
An addition to the King Air line in June 1979 is the F90, a fuel-efficient version, thanks in part to the new Pratt & Whitney engines with improved turbine blades which extract more power from the engine, four-blade propellers and full deicing equipment. At 300 mph true air speed it burns less than 70 gallons per hour. Slower-turning props also reduce interior noise levels. This combined the pressurised fuselage of the Model 90, with the wings and tail unit of the Models 100 King Air and 200 Super King Air respectively. The dual wheel gear are fitted with brake deice systems. The pressurization differential of 5.0 pounds/sq.in. provides a sea-level cabin at 11,000 feet. The F90 was powered by 750-shaft-horsepower Pratt & Whitney PT6A-135 engines and sold for $954,500.
In 1976 the Naval Air Systems Command selected Beech win-ner of an industry, competition for a three-year pur-chase of new multi-engine training aircraft for Naval aviators. The Navy selected an aircraft that combined features of the C90 and E90, designated T-44A. The aircraft is powered by two 550 shp PT6A-34B turbo-prop engines. A total of 15 aircraft purchased by the Navy are to replace piston-engine-powered TS-2A and TS-2B trainers.
Students selecting the Specialized Undergraduate Pilot Training [SUPT] turboprop track attend T-44 training conducted by the U.S. Navy at Corpus Christi, Texas, and then go on to flying duties in turboprop aircraft. Training includes the Navy common maritime turboprop course followed by an Air Force top-off course. The top-off course consists of single aircraft and formation tactical low level airdrop procedures. Training takes approximately 26 weeks and includes 152 hours ground training, 30 hours in the flight simulator and 111 flying hours in the T-44. The T-44 is equipped with deicing and anti-icing systems augmented by instrumentation and navigation equipment which allows flight under instrument and icing conditions. The interior includes a seating arrangement for an instructor pilot (right seat), a student pilot (left seat), and a second student. Two additional passenger seats are included. A distinguishing feature of the aircraft is the avionics fault insertion capabilities afforded the instructor pilot from the right-seat armrest and the second student/observer audio control panel that allows the second student to monitor all radio communications.
The T-44A aircraft was procured as a commercial-derivative aircraft certified under an FAA Type Certificate. Throughout its life, the aircraft has been operated and commercially supported by the Navy using FAA processes, procedures and certifications. It continues to be maintained commercially at all levels of maintenance, and relies on COTS/NDI components and equipment to support airworthiness. Aircraft modification efforts are "turnkey" projects (procurement and installation) implemented as part of competitively awarded maintenance contracts. Where extensive integration efforts are required, the non-recurring engineering phase, including test and certification, is typically performed by Raytheon Aircraft Company under a sole-source engineering contract with the Navy.
The 3,000th example of the King Air family was delivered to a customer on 17 April 1981.
While production of the F90 ended at 231 aircraft, the C90 continued in production, 1,415 of the low-tailplane variants having been delivered by early 1989.
Engines two 500-shp Pratt & Whitney turboprops.
Gross Wt. 9650 lbs.
Empty Wt. 5685 lbs.
Fuel capacity 384 USG.
Cruise 260 mph.
Stall 87 mph.
Initial climb rate 1900 fpm.
Ceiling 27,000 ft.
Range 1480 sm.
Takeoff distance (50’) 1420 ft.
Landing distance (50’) 2300 ft.
C90 King Air
First built: 1964.
Engines: 2 x P&W PT6A-21, 550 shp.
Props: Hartzell 3-blade, 93.4-in.
Length: 35.5 ft.
Height: 14.3 ft.
Wingspan: 50.3 ft.
Wing area: 294 sq.ft.
Wing aspect ratio: 8.6.
Maximum ramp weight: 9705 lbs.
Maximum takeoff weight: 9650 lbs.
Standard empty weight: 5765 lbs.
Maximum useful load: 3940 lbs.
Maximum landing weight: 9168 lbs.
Wing loading: 32.8 lbs/sq.ft.
Power loading: 8.8 lbs/hp.
Maximum usable fuel: 2573 lbs.
Best rate of climb: 1955 fpm.
Service ceiling: 28100 ft.
Max pressurisation differential: 4.6 psi.
8000 ft cabin alt @: 21200 ft.
Maximum single-engine rate of climb: 539 fpm @ 108 kts.
Single-engine climb gradient: 299 ft/nm.
Single-engine ceiling: 15050 ft.
Maximum speed: 224 kts.
Normal cruise @ 18,000ft: 218 kts.
Max range cruise: 197 kt.
Fuel flow @ normal cruise: 432 pph.
Endurance at normal cruise: 5.4 hr
Range max fuel/cruise: 881nm/4.0hr.
Range max fuel /range: 1251nm/6.4hr.
Stalling speed clean: 89 kts.
Stalling speed gear/flaps down: 76 kts.
1.3 Vso: 99 kt.
Turbulent-air penetration speed: 169 kts.
Cruise: 247 kt.
Range 7 POB & res: 1100 nm
Engine: 2 x P&WAC PT6A-28, 550 hp.
Wing loading: 34.4 lb/sq.ft.
Pwr loading: 9.2 lb/hp.
Gross wt: 10,160 lb.
Empty wt: 5961 lb.
Equipped useful load: 3949 lb.
Payload max fuel: 773 lb.
Range max fuel/cruise: 1004nm/4hr.
Range max fuel /range: 1609nm/7.5hr.
Ceiling: 27,620 ft.
Max cruise: 248 kt.
Max range cruise: 216 kt.
Vmc: 86 kt.
Stall: 77-86 kt.
1.3 Vso: 100 kt.
ROC: 1870 fpm.
SE ROC: 470 fpm @ 111 kt.
SE ceiling: 14,390 ft.
Min field length: 2110 ft.
Takeoff distance (50’) 2024 ft.
Landing distance (50’) 2110 ft.
Fuel cap: 3176 lb / 474 USG.
Cabin pressure: 4.6 psi.
F90 King Air
First built: 1979.
Engines: 2 x P&W PT6A-135, 750 shp / 559kW.
Props: Hartzell 4-blade, 92-in.
Wingspan: 13.99 m / 45 ft 11 in
Length: 12.13 m / 39 ft 10 in
Height: 4.8 m / 15 ft 9 in
Wing area: 25.98 sq.m / 279.65 sq ft
Wing aspect ratio: 7.5.
Maximum ramp weight: 11,030 lbs.
Maximum takeoff weight: 10,950 lbs.
Standard empty weight: 6549 lbs.
Maximum useful load: 4481 lbs.
Zero fuel wt: 9,600 lbs.
Maximum landing weight: 10,950 lbs.
Wing loading: 39.1 lbs/sq.ft.
Power loading: 7.3 lbs/hp.
Maximum usable fuel: 3149 lbs.
Best rate of climb: 2380 fpm.
Service ceiling: 29,802 ft.
Max pressurisation differential: 5 psi.
8000 ft cabin alt @: 23,120 ft.
Maximum single-engine rate of climb: 600 fpm @ 117 kts.
Single-engine climb gradient: 309 ft/nm.
Single-engine ceiling: 14,419 ft.
Maximum speed: 267 kts.
Normal cruise @ 22,000ft: 257 kts.
Fuel flow @ normal cruise: 538 pph.
Endurance at normal cruise: 5.3 hrs:
Stalling speed clean: 94 kts.
Stalling speed gear/flaps down: 77 kts.
Turbulent-air penetration speed: 169 kts.
1967 Staff transport
Engines: two 550hp P&W PT6A-20
Wingspan: 45' 11 in
Useful load: 4220 lb
Max speed: 265 mph
Range: 1675 mi
No built: 140, 66-18000/18047, 67-18048/18076, -18078/18084, -18086, -18088, -18090/18092, -18094/18103, -18116/18118
4 for electronic warfare as RU-21A, 67-18112/18115
4 modified for electronic reconnaissance as EU-21A, 66-18000, -10803, -18007, 67-18058
2 for ground instruction as GU-21A, 66-18006, -18012
4 for special development tasks as JU-21A, 66-18008, 67-18063, -18065, -18069
1967 Special military applications
No built: 3 67-18077, -18087, -18093
1967 Staff transport
No built: 2 67-18085, -18089
1967 Modified cockpit
No built: 18 67-18104/18111, -18119/18128, plus 18 U-21A conversions
No built: 1 unknown modification 67-18125
1971 Staff transport.
No built: 15 70-15875/15890; with 3 modified RU-21D
1971 Electronic countermeasures
No built: 17 70-15891/15907
1971 Staff transport
No built: 32
1972 Battlefield surveillance
No built: 20 71-21058/21060
3 modified for a short time from C-12L, then reverted