The Beechcraft Model 18 is a 6 to 11 seat, twin-engined, low-wing, tail-wheel light aircraft manufactured by the Beech Aircraft Corporation of Wichita, Kansas.
Continuously produced from 1937 to November 1969 (over 32 years, a world record at the time), over 9,000 were built, making it one of the world’s most widely used light aircraft.
Sold worldwide as a civilian executive, utility, cargo aircraft, and passenger airliner on tail-wheels, nose-wheels, skis, or floats, it was also used as a military aircraft.
During and after World War II, over 4,500 Beech 18s were used in military service as light transport, light bomber (for China), aircrew trainer (for bombing, navigation, and gunnery), photo reconnaissance, and “mother ship” for target drones, including United States Army Air Forces (USAAF) C-45 Expeditor, AT-7 Navigator, and AT-11 Kansan; and United States Navy (USN) UC-45J Navigator, SNB-1 Kansan, and others.
In World War II, over 90% of USAAF bombardiers and navigators trained in these aircraft.
Production got an early boost when Nationalist China paid the company US$750,000 for six M18R light bombers, but by the time of the U.S. entry into World War II, only 39 Model 18s had been sold, of which 29 were for civilian customers.
Work began in earnest on a variant specifically for training United States Army Air Forces (USAAF) military pilots, bombardiers, and navigators.
The effort resulted in the Army AT-7.
Further development led to the AT-11 navigation trainer, C-45 military transport, and F-2 (the “F” standing for “Fotorecon”, short for “photographic reconnaissance”).
The United States Navy first adopted the Beech 18 as the JRB-1, equivalent to the F-2, followed by the JRB-2 transport; the JRB was initially named the Voyager, but this name did not enter common use, and JRBs were generally called Expeditors like their USAAF counterparts.
The first JRB-1 obtained by the Navy, bureau number (BuNo) 09771, was converted from the last civil Model 18 built before production was earmarked solely for the military for the duration of the war.
The Navy subsequently obtained more Model 18s as the JRB-3 (C-45B), JRB-4 (UC-45F), SNB-1 Kansan (AT-11), SNB-2 (AT-7), and SNB-2C (AT-7C).
Existing naval Twin Beeches were subsequently modified into the SNB-2H air ambulance, SNB-2P reconnaissance trainer, and SNB-3Q electronic countermeasures trainer.
The United States Coast Guard acquired seven JRB-4 and JRB-5 aircraft from the Navy between 1943 and 1947; they were primarily used as utility transports, with one aircraft later converted for aerial mapping, and another used for proficiency flying.
After the war, the USAAF became the United States Air Force (USAF), and the USAF Strategic Air Command had Model 18 variants (AT-11 Kansans, C-45 Expeditors, F-2 Expeditors, and UC-45 Expeditors) from 1946 until 1951.
In 1950, the Navy still had around 1,200 JRB and SNB aircraft in inventory.
From 1951 to 1955, the USAF had many of its aircraft remanufactured with new fuselages, wing center sections, and undercarriages to take advantage of the improvements to the civil models since the end of World War II.
Eventually, 900 aircraft were remanufactured to be similar to the then-current Model D18S and given new designations, constructor’s numbers, and Air Force serial numbers.
The USN had many of its surviving aircraft remanufactured as well, resulting in the JRB-6, the SNB-5, and SNB-5P.
The Coast Guard retired its JRBs in 1956 and sold most of them as surplus in 1959, but one was retained by the United States Coast Guard Reserve until at least 1972.
With the adoption of the 1962 United States Tri-Service aircraft designation system, the Navy’s SNB-5 and SNB-5P became the TC-45J and RC-45J respectively, later becoming the UC-45J as their primary mission shifted from aircrew training to utility transport work.
The C-45 flew in USAF service until 1963, the USN retired its last UC-45J in 1972, while the U.S. Army flew its C-45s until 1976.
In later years, the military called these aircraft “bug smashers” in reference to their extensive use supplying mandatory flight hours for desk-bound aviators in the Pentagon.
Beech 18s were used extensively by Air America during the Vietnam War, initially more or less standard ex-military C-45 examples were used, but then the airline had 12 aircraft modified by Conrad Conversions in 1963 and 1964 to increase performance and load-carrying capacity.
The modified aircraft were known as Conrad Ten-Twos, as the maximum take-off weight (MTOW) was increased to 10,200 lb (4,600 kg).
The increase was achieved by several airframe modifications, including increased horizontal stabilizer angle of incidence, redesigned undercarriage doors, and aerodynamically improved wingtips.
Air America then had Volpar convert 14 aircraft to turboprop power, fitted with Garrett AiResearch TPE-331 engines; modified aircraft were called Volpar Turbo Beeches, and also had a further increase in MTOW to 10,286 lb (4,666 kg).
Military versions
USAAC/USAAF designations
C-45
Six seat staff transport based on C18S.
C-45A
Eight seat utility transport based on C18S
RC-45A
Redesignation of all surviving F-2, F-2A, and F-2B aircraft by the USAF in 1948
C-45B
Based on C18S, but with modified internal layout; redesignated UC-45B in 1943
C-45C
Two Model 18S aircraft impressed into the USAAF, redesignated UC-45C in January 1943
C-45D
Designation given to two AT-7 aircraft converted as passenger transports during manufacture, redesignated UC-45D in January 1943
C-45E
Designation given to two AT-7 and four AT-7B aircraft converted as passenger transports during manufacture, redesignated UC-45E in January 1943
C-45F
Standardized seven-seat version based on C18S, with longer nose than preceding models, redesignated UC-45F
C-45G
AT-7s and AT-11s remanufactured in the early 1950s for the USAF to similar standard as civil D18S with autopilot and R-985-AN-3 engines
TC-45G
Multiengine crew trainer variant of C-45G; AT-7s and AT-11s remanufactured in the early 1950s for the USAF to similar standard as civil D18S
C-45H
AT-7s and AT-11s remanufactured in the early 1950s for the USAF to similar standard as civil D18S, with no autopilot and R-985-AN-14B engines
TC-45H
RC-45J
In 1962, all surviving U.S. Navy SNB-5Ps were redesignated RC-45J
TC-45J
In 1962 all surviving U.S. Navy SNB-5s were redesignated TC-45J
UC-45J
Subsequent redesignation of RC-45J and TC-45
AT-7 Navigator
Navigation trainer based on C18S, with an astrodome and positions for three students, powered by 450-hp Pratt & Whitney R-985-25 engines
AT-7A
Floatplane version of AT-7
AT-7B
Winterized AT-7
AT-7C
Based on C18 with R-985-AN3 engines
AT-11 Kansan
Bombing and gunnery trainer for USAAF derived from AT-7, fuselage had small, circular cabin windows, bombardier position in nose, and bomb bay; gunnery trainers were also fitted with two or three .30-caliber machine guns, early models (the first 150 built) had a single .30-cal AN-M2 in a Beechcraft manufactured top turret, later models used a Crocker Wheeler twin .30-cal top turret, a bottom tunnel gun was used for tail gunner training, 1,582 built for USAAF orders, with 24 ordered by Netherlands repossessed by USAAF and used by the Royal Netherlands Military Flying School at Jackson, Mississippi.
AT-11A
Conversion of AT-11 as navigation trainer
CQ-3
Conversion of UC-45F, modified to act as drone control aircraft, redesignated as DC-45F in June 1948
F-2
Photo-reconnaissance version based on B18
F-2A
Improved version
F-2B
US Navy designations
JRB-1
Photographic aircraft, based on the C18S, fitted with fairing over cockpit for improved visibility, 11 obtained, at least one conversion from impressed civil B18S
JRB-2
Light transport, based on the C18S, 15 obtained, at least one conversion from JRB-1 some transferred from USAAF C-45A stocks
JRB-3
Photographic version, similar to C-45B; 23 obtained, some transferred from USAAF C-45B stocks
JRB-4
Utility transport version, equivalent to UC-45F
JRB-6
Remanufactured JRB
SNB-1
Similar to AT-11
SNB-2
Navigation trainer similar to AT-7
SNB-2C
Navigation trainer similar to AT-7C
SNB-2H
Ambulance conversion
SNB-2P
Photo-reconnaissance trainer conversion
SNB-3Q
Electronic countermeasures trainer conversion
SNB-5
Remanufactured SNB or JRB
SNB-5P
Remanufactured SNB-2P
RAF/RCAF Lend-lease designations
Expeditor I
C-45Bs supplied to the RAF under Lend-Lease
Expeditor II
C-45Fs supplied to the RAF and Royal Navy under Lend-Lease
Expeditor III
C-45Fs supplied to the RCAF under Lend-Lease
Post-war RCAF designations
C-45Ds delivered between 1951 and 1952
Expeditor 3N
Navigation trainer
Expeditor 3NM
Navigational trainer that could be converted to a transport
Expeditor 3NMT
3NM converted to a transport aircraft
Expeditor 3NMT(Special)
Navigation trainer/personnel transport
Expeditor 3TM
Transport with fittings so it could be converted to a navigation trainer
Expeditor 3TM(Special)
Modified RCAF Expeditors used overseas in conjunction with Project WPB6
Canadian Armed Forces
CT-128 Expeditor
1968 redesignation of existing RCAF aircraft upon unification of the Canadian Armed Forces
