In December 1971 Cessna announced the introduction of the pressurised Model 340 developed from the Model 310. Powered by twin TSIO-520-NB engines each giving 213kW, the 340 incorporated the wing and tricycle landing gear developed for the Model 414, married to a new pressurised fuselage, but using the tail of the Model 310. Though aimed at the owner-pilot of light twins, the 340 has such features as center-aisle seating, an air-stair door and cruise performance of 241 mph at 20,000 feet.
The 1972 model 340, grosses at 5,975 pounds and offers a top speed at 16,000 feet of 260 mph. Pressurized to a maximum differential of 4.2 psi, the fuselage is more than five feet longer than that of the 310, and the horizontal tail surfaces have much more leverage. The result is significantly improved pitch control at landing speeds. Normal fuel is 50 gallons in each tip: optional inboard aux tanks hold 20 each and another 20 will fit in a tank at the rear of each engine nacelle, for a possible total of 184 gallons and a range of more than 1,200 miles with four aboard. Standard useful load of the 340 is 2,278 pounds. Allowable baggage includes 350 pounds in a 15.5 cubic foot nose compartment, 340 pounds in an 18.5 cubic foot rear fuselage compartment and 120 pounds in each nacelle locker for a total of 930 pounds. The 340 at sea level and gross weight will climb at a heady 1,500 fpm. At gross on one engine the airplane will climb at 250 f`pm with the gear up. But keep in mind that this airplane is turbocharged, and will hold that r/c for a long time: it can climb on one all the way to 12,100 msl and still be going up at100 fpm. When it is loaded the 340 is not a power-off airplane - not with a wing loading of 32.5 lbs/sq. ft. - nor is it a short field airplane. Takeoff over the 50 ft obstacle requires 2,430 feet at gross, whereas you can land over the same obstacle in only 1,840. Without troubling passengers or crew with oxygen masks it can go to 20,000 ft with a cabin altitude of only 8,000 feet.
This was followed in the mid-1970s by the Model 340A equipped with 231kW engines and later by the similarly powered Model 340A II fitted with comprehensive factory-installed avionics allowing IFR operation. In 1978 Cessna introduced the Model 340A III equipped with an improved avionics package including colour weather radar and this version remained available until 1985 when the type was taken out of production, by which time 1,287 had been delivered.
A lightweight unpressurised version of the Model 340 was offered to the market in 1979 as the Model 335, later available as the improved Model 335 II version, but production ended in 1980 after only 45 had been built.
Riley Super 340
Engines: Continental TSIO-520-NB, 310 hp to 20,000 ft
TBO: 1400 hrs.
Oil capacity (qts.): 12
Props: McCauley CS 3-blade, 76.5-in.
Landing Gear type: Tri./Retr.
Wingspan: 38 ft. 1 in.
Overall length: 34 ft. 4 in.
Height: 12 ft. 7 in.
Wing area: 184 sq.ft.
Wing aspect ratio: 7.2.
Maximum ramp weight: 6025 lbs.
Maximum takeoff weight: 5990 lbs.
Max landing weight (lbs.): 5990
Standard empty weight: 3948 lbs.
Maximum useful load: 2077 lbs.
Zero-fuel weight: 5630 lbs.
Fuel capacity: (total): standard: 102 USgal.
Fuel capacity with auxiliary tanks (40 gal. usable): 143 gal.
Fuel capacity with auxiliary tanks (63 gal. usable): 166 gal.
Fuel capacity with auxiliary tanks (63 gal.) and wing locker tanks, 207 gal.
Maximum landing weight: 5,990 lbs.
Wing loading: 32.5 lbs/sq.ft.
Power loading: 9.7 lbs/hp.
Best rate of climb: 1,650 fpm @ 108 kts.
Climb gradient: 930 ft/nm.
Rate of climb @ 8,000 ft: 1500 fpm.
Service ceiling (ft.): 29,800
Certificated ceiling: 30,000 ft.
8000ft cabin alt @: 20,000 ft.
Maximum single-engine rate of climb: 315 fpm @ 100 kts.
Single-engine climb gradient: 189 ft/nm.
Single-engine service ceiling: 15800 ft.
Maximum speed: 244 kts.
Cruise @ 65% pwr @ 8,000ft: 182 kts.
Cruise @ 65% power @ 18,000ft: 196 kts.
Fuel flow @ 65% pwr @ 18,000 ft: 180 pph.
Endurance at 65 % pwr @ 18,000 ft: 6.5 hrs.
Cruise speed (kts.) 75% power @ 25,000 ft.: 229
Cruise speed (kts.) 65% power @ 25,000 ft.: 219
Cruise speed (kts.) 55% power @ 25,000 ft.: 202
Max range (w/ reserve) (nm) 75% power @ 25,000 ft.: 1106
Max range (w/ reserve) (nm) 65% power @ 25,000 ft.:1248
Max range (w/ reserve) (nm) 55% power @ 25,000 ft.:1377
Stalling speed clean: 79 kts.
Stalling speed gear/flaps down: 71 kts.
Turbulent-air penetration speed: 155 kts.
SL cabin at: 9,000 ft
8000-foot cabin at 20,000 feet.
Takeoff ground roll (ft.): 1615
Takeoff over 50-ft. obstacle (ft.): 2175
Landing ground roll (ft.): 770
Landing over 50-ft. obstacle (ft.): 1850
Baggage allowable: 930 lbs.
Cabin doors: 1
Cabin width (in.): 46.5
Cabin height (in.): 49
Wheel track: 12 ft. 11 in.
Wheel base: 10 ft. 3 in.
1977 Price: $290,000
Engines Continental TSIO-520-M, 310 hp to 20,000 feet.
TBO 1,400 hrs.
Propellers constant-speed, full -feathering, three-blade, 76.5-in, diameter.
Length 34 ft. 4 in.
Height 12 ft. 7 in.
Wingspan 38 ft. 1 in.
Wing area 184 sq. ft.
Wing loading 32.5 lbs/sq.ft.
Empty weight 4,527 lbs.
Useful load 1,463 lbs.
Gross weight 5,990 lbs.
Payload with full fuel 365 lbs.
Power loading 10.48 lbs./hp.
Usable fuel 183 USG./1,098 lbs.
Minimum runway requirement 2,175 ft.
Rate of climb 1,650 fpm.
Single-engine rate of climb 315 fpm.
Service ceiling 29,800 ft.
Single-engine service ceiling 15,800 ft.
Maximum speed 242 knots.
Maximum cruise (77.5% power @ 24,500 ft) 228 knots.
Economy cruise (56.1 % power @ 25,000 feet) 190 knots.
Range at maximum cruise (45-min res, 1,098 lbs. fuel) 996 nm.
Range at economy cruise (45-min res, 1,098 lbs. fuel) 1,133 nm.
Duration at maximum cruise, no res 5.23 hrs.
Stall speed (clean) 83 knots.
Stall speed (gear, flaps down) 71 knots.
Engines: 2 x Continental TSIO-520-N, 310 hp.
Props: constant speed, full-feathering, 3 blades, 76.5 inch dia.
Wing span: 38 ft. 1 in.
Wing area: 184 sq.ft.
Length: 34 ft. 4 in.
Height: 12 ft, 7 in.
MTOW: 5990 lbs.
Std empty wt: 4096 lbs.
Max altitude: 20,000 ft.
Max speed: 241 kt.
Max recommended cruise: 77.5% power: altitude: 10,000 ft. speed: 198 knots
Max recommended cruise: 77.5% power: altitude: 24,500 ft. speed: 220 knots.
Range max cruise 77.5% power: altitude: 10,000 ft, endurance: 2.18 hrs. range: 425 nm
Range max cruise 77.5% power: altitude: 24,500 ft. endurance: 3.99 hrs. range: 861 nm.
ROC sea level: twin-engine: 1650 fpm
ROC single-engine: 315 fpm.
Service ceiling: twin-engined: 29,800 ft.
Ceiling single-engine: 15,800 ft.
Ground run: 1615 ft. / 50 ft. obstacle: 2230 ft.
Ground roll: 760 ft. / 50 ft. obstacle: 1850 ft.
Baggage allowable: 930 lbs.
Wing loading: 32.55 lb/sq.ft.
Power loading: 9,66 lb/hp.
Fuel capacity: (total): standard: 102 gal. with auxiliary tanks (40 gal. usable): 143 gal.
Fuel capacity: with auxiliary tanks (63 gal. usable): 166 gal.
Fuel capacity: with auxiliary tanks (63 gal.) and wing locker tanks, 207 gal.
Price 1977: US$210,450