The “Twin Beech” is one of the most versatile and successful aeroplanes ever designed, spawning more than 200 Supplemental Type Certificates from the Federal Aviation Administration alone. It was designed from the outset for both civilian and military markets. Sales were initially slow, customers preferring the slightly larger Electra, and just 39 Beech 18s had been delivered by the time the United States entered World War II. With Lockheed concentrating its war effort elsewhere, Beech was able to find a niche for its Model 18 and large numbers were produced as communications and crew training aircraft for the United States Army Air Corps and Navy. Post-war, the Twin Beech was reinvented for the civilian market, while large numbers of surplus military aircraft were remanufactured and modernized for continued service. Large numbers survive, with many still active commercially in the Canada, the United States and the Philippines. The Beech 18 is also well represented in museums across the globe.
First flight: 15 Jan 37 (c/n 62, X15810)
Production: 9,248, comprising 7,330 new-build at Wichita, KS, and 1,918 re-manufactured aircraft.
First delivery: 1 Nov 37 (c/n 171, NC18567)
Last delivery: Jan 68 (c/n BA-765, JA5174)
Principal variants:
Civil versions: 18A - prototype and initial production civil version powered by 2 Wright R-760-E2 radials, featuring taildragger-type landing gear and circular, twin fins (3 built);
A18A - 18A optimised for cold weather operation (3 built);
18B - 18A powered by 2 Jacobs L-5s (4 built);
18D - 18B powered by 2 Jacobs L-6s (7 built);
18S/B18S - definitive early civil configuration featuring Pratt & Whitney R-985 Wasp Juniors (used on all subsequent Beech 18s, except the D18C/C-T), oval tail fins and other detail improvements over the 18D (6 18S and 5 B18S built);
A18D - 18S with revised tail surfaces to improve single-engine performance (3 built);
C18S - designation applied to aircraft diverted to civil use from C-45B, C-45F, AT-7C and AT-11 production and also to post-war civilianisations (47 built, including 3 built up by Southwestern Aero Exchange from parts acquired from Beech);
D18S - post-war commercial version based on C-45F/JRB-4 (1,003 built, including 280 for Royal Canadian Air Force as Expeditor 3, comprising 99 3N navigation trainers, 135 3NM navigation trainers capable of operating as transport aircraft, and 36 3TM five-seat transport aircraft capable of use for navigation training. The total of 1,003 also includes 20 bomber training aircraft designated D18S for supply to Nationalist China);
D18C/C-T - D18S powered by Continental R-9As (16 built of each, the C for corporate use and the C-T as a feederliner);
Super E18S - D18S with increased weight and payload, uprated engines and improvements to the passenger cabin, including heightened fuselage, increased window area and integral air-stair (460 built);
Super G18S - E18S with improved cockpit comfort (156 built);
Super H18 - G18S with detail improvements (149 built, 109 of which were fitted with Volpar tri-gear kits at the factory).
Military versions: 18R - 18S with Wright R975-E3 Whirlwinds and optimised for operation in northern Sweden (1 built);
M18R - bomber crew training version of 18R with clear nose and gun turret for Nationalist China (6 built);
AT-7 Navigator, AT-7A, AT-7B and AT-7C Navigator - navigator training version powered by Pratt & Whitney R-985-25 Wasp radials for the US Army Air Corps (1,147 built, comprising 583 AT-7, 7 AT-7A, 9 AT-7B and 549 AT-7C);
AT-11 Kansan - bomber training version for the US Army Air Corps, based on M18R but powered by R-985-AN-1s (1,583 built)
C-45 - 6-seat staff transport version of the B18S for the US Army Air Corps (11 built);
C-45A Voyager - 8-seat staff transport with aerial photography capability for US Army Air Corps (20 built);
UC-45B Expeditor - 5-seat staff transport with navigator training and aerial photography capability for US Army Air Corps (203 built, of which 58 were delivered to the RAF and RN as Expediter I and 63 to the Royal Canadian Air Force as Expediter I);
UC-45D Expeditor - UC-45B with detail modifications to landing gear systems (3 built);
UC-45F Expeditor - 7-seat version of UC-45B, with navigator training and aerial photography capability deleted (1,116 built, including 278 for the RAF and Fleet Air Arm as Expediter II and 45 for the Royal Canadian Air Force as Expediter II);
C-45G/H Expeditor - post-war remanufactured versions using wings, tail and engines from surplus T-7/T-7Cs, AT-11s, UC-45B/Fs considered to be new build by both Beech and the US Air Force; featuring numerous improvements and accommodation for 4 passengers, with the only difference between ‘G and ‘H models being the choice of propeller (372 C-45G and 432 C-45H built; 17 C-45Gs were converted to RC-45G for aerial photography);
TC-45G Expeditor - C-45G optimised for navigator training (96 built);
F-2 - B18S optimised for high-altitude aerial photography, for US Army Air Corps (14 built);
F-2B - C-45F diverted on the line and equipped for high-altitude aerial photography (42 built, plus 17 converted);
JRB-1 - US Navy version of C-45, with minor changes (11 built);
JRB-2 Expeditor - US Navy version of C-45A (15 built);
JRB-3 Expeditor - US Navy version of UC-45B (20 built);
JRB-4 Expeditor - US Navy version of UC-45F (324 built);
JRB-5 Expeditor - 7-seat transport version for the US Navy (42 converted from SNB-2s);
JRB-6 Expeditor - post-war 5-seat passenger transport for the US Navy remanufactured from SNB-1s and equivalent to C-45G; also considered to be new builds (85 built);
SNB-1 Kansan - gunnery and bomber crew training version for US Navy (320 built, plus 141 converted from surplus USAAF AT-11s);
SNB-2 Navigator - US Navy version of AT-7 (240 built, plus 117 converted from surplus USAAF AT-7s);
SNB-2C Navigator - US Navy version of AT-7C (375 built);
SNB-3 - 5-seat utility version of the SNB-2/SNB-2C with navigation training equipment deleted (372 converted, including 103 as specialist versions for training radar operators and for aerial photography);
SNB-4 - 4- or 5-seat utility version, with provision for navigation training (65 built as re-manufactured USAAF AT-11s);
SNB-5 - post-war utility version (26 built new for export to France and Netherlands and 799 remanufactured from earlier JRB/SNB models to standardise the US Navy inventory, including 1 as SNB-5N. Surviving aircraft were re-designated UC-45J in 1962);
SNB-5P - post-war aerial photography version of SNB-5, remanufactured from earlier JRB/SNB models (43 built; became RC-45J in 1962).
Other conversions have included at least 323 aircraft modified with Volpar tri-gear kits (in addition to the 109 H18s referred to above), of which approximately 40 have also had Hamilton Aviation extended nose kits fitted (including the Westwind IIIs; the non-Westwind conversions are indicated on the list of Survivors by the suffix HEN);
Infinite I - Dumod Corporation modification, featuring Volpar tri-gear, wrap-around windshield, picture windows and other cabin comfort improvements (10 converted at Opa-locka - Executive, FL; subsequently re-named Dumod I);
Infinite II - stretched fuselage version of Infinite I (3 converted at Opa-locka - Executive, FL; subsequently Dumod Liner);
Turbo 18 - Volpar modification, featuring its tri-gear kit and Garrett TPE-331 turboprops (20 converted, including 15 at Tainan, Taiwan, by Air Asia for Air America; first flight Dec 64);
Turboliner - stretched version of Turbo 18, with accommodation for 15 passengers (19 converted by Volpar; first flight 12 Apr 67);
Turboliner II - futher modification of Turboliner for cold weather operations (11 converted by Volpar);
Tradewind - Pacific Aerospace conversion featuring single tail-fin and Volpar tri-gear kit; STC currently owned by Vancouver Island Air which completed the latest conversion as a Seawind floatplane (22 converted; first flight 13 Jul 62);
Turbo Tradewind - Tradewind powered by Pratt & Whitney PT6A-6 turboprops (4 converted, including 3 by American Turbine Engine Co (ATE) as Westwind IV; first flight 3 Nov 64);
Westwind I: ATE conversion, featuring Volpar tri-gear and PT6A-20 turboprops (14 converted);
Westwind II: stretched fuselage version of Westwind II (1 converted by ATE);
Westwind III: ATE conversion, retaining tail-wheel undercarriage and featuring PTA6A-20 turboprops; STC acquired in Mar 71 by Hamilton Aviation, Tucson, AZ, and further modified with Hamilton’s extended nose to improve centre of gravity (1 converted by ATE and 22 by Hamilton, including 12 converted from Westwind I).
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