The Beechcraft Model 18, a twin-engine, low-wing, tail-wheel light aircraft with 6 to 11 seats, was manufactured by the Beech Aircraft Corporation in Wichita, Kansas.
It was continuously produced from 1937 until November 1969, a span of over 32 years, setting a world record at that time. With over 9,000 units built, it became one of the most popular light aircraft globally.
The Model 18 was sold internationally for various uses, including as a civilian executive, utility, cargo aircraft, and passenger airliner, adaptable for tail-wheels, nose-wheels, skis, or floats.
It also served military purposes. During and post-World War II, more than 4,500 Beech 18s were utilised in military operations as light transport, light bombers (for China), aircrew trainers (for bombing, navigation, and gunnery), photo reconnaissance, and as “mother ships” for target drones.
This included roles such as the USAAF C-45 Expeditor, AT-7 Navigator, and AT-11 Kansan, as well as the USN UC-45J Navigator, SNB-1 Kansan, among others.
In WWII, these aircraft were instrumental in training over 90% of USAAF bombardiers and navigators.
The Model 18’s production received an early surge when Nationalist China invested US$750,000 in six M18R light bombers.
However, by the time the U.S. entered WWII, only 39 had been sold—29 to civilian customers.
The USAAF then initiated a dedicated effort to develop a variant for training military pilots, bombardiers, and navigators, leading to the creation of the Army AT-7.
This development continued, resulting in the AT-11 navigation trainer, the C-45 military transport, and the F-2, designated for photographic reconnaissance.
The US Navy first introduced the Beech 18 as the JRB-1, equivalent to the F-2, followed by the JRB-2 transport.
Initially named the Voyager, the JRB did not commonly use this name and was generally referred to as the Expeditor, akin to its USAAF counterparts.
The Navy’s first JRB-1, with the bureau number 09771, was a conversion from the final civilian Model 18 build.
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
The USAAF’s bombing and gunnery trainer, derived from the AT-7, featured small, circular cabin windows, a bombardier’s position in the nose, and a bomb bay.
Gunnery trainers were equipped with two or three .30-caliber machine guns.
The early models, the first 150 built, included a single .30-cal AN-M2 machine gun in a Beechcraft-manufactured top turret, while later models were fitted with a Crocker Wheeler twin .30-cal top turret.
Additionally, a bottom tunnel gun was utilised for tail gunner training.
In total, 1,582 units were built for USAAF orders, and 24 units initially ordered by the Netherlands were repossessed by the USAAF and employed by the Royal Netherlands Military Flying School in 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
