Beech C-45 ( Beech 18 )

Among the most notable cooling air and exhaust modifications were those engineered by Benjamin Israel while employed by Conrad Conversions.

His modifications were based largely on creating a more efficient use of cooling air to reduce drag, a major detriment to cruise performance.
Cruise performance was improved 10% or more at the same power settings as before the modifications.

These modifications were largely copied on the factory produced G and H models.

Beech 18s were used extensively by [Vous devez être inscrit et connecté pour voir ce lien] during the [Vous devez être inscrit et connecté pour voir ce lien]; 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 landing gear doors, and aerodynamically-improved wing tips.

Air America then had Volpar convert 14 aircraft to [Vous devez être inscrit et connecté pour voir ce lien] power, fitted with [Vous devez être inscrit et connecté pour voir ce lien] engines; modified aircraft were called Volpar Turbo Beeches and also had a further increase in MTOW to 10,286 lb (4,666 kg).

A factory option at one point was the addition of [Vous devez être inscrit et connecté pour voir ce lien] bottles on each engine nacelle which added the equivalent of 200 horsepower (150 kW) per engine for about 12 seconds.

The most successful powerplant upgrade was that of the [Vous devez être inscrit et connecté pour voir ce lien] turbine engine and Hartzell propeller.

This conversion was carried out by [Vous devez être inscrit et connecté pour voir ce lien] in the 1960s and 70s as the Hamilton Westwind, successfully extending the commercial life of the aging aircraft.
The Westwind II added a fuselage stretch to provide seating for 17 passengers, the Westwind III seated eight and used the remainder of the extra room for cargo, and the Westwind IV added an extra stretch and a large cargo door.

Un Beech 18 transformé par Hamilton en Westwind III

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Spar Problems


The [Vous devez être inscrit et connecté pour voir ce lien] of the Model 18 is fabricated by welding an assembly of tubular steel.

The configuration of the tubes and inadequate corrosion inhibitors, along with holes from after-market [Vous devez être inscrit et connecté pour voir ce lien]
modifications have allowed the spar to become susceptible to corrosion and cracking while in service.

This prompted the FAA to issue an [Vous devez être inscrit et connecté pour voir ce lien] in 1975, mandating the fitment of a spar strap to Model 18s.
This led in turn to the retirement of a large number of Model 18s when owners determined that the aircraft were worth less than the cost of the modifications.

Further requirements have been mandated by the FAA and other national airworthiness authorities, including regular removal of the spar strap to allow the strap to be checked for cracks and corrosion and the spar to be [Vous devez être inscrit et connecté pour voir ce lien].

In Australia the airworthiness authority has placed a life limit on the airframe, beyond which aircraft are not allowed to fly.

Variants


Manufacturer Models


Unless otherwise noted, the engines fitted are [Vous devez être inscrit et connecté pour voir ce lien] radials.


Model 18A

First production model with seating for two pilots and seven or eight passengers, fitted with [Vous devez être inscrit et connecté pour voir ce lien]E-2 engines of 350 horsepower (260 kW). MTOW: 6,700 lb (3,000 kg).

• Model S18A
  

Version of Model 18A capable of being fitted with skis or [Vous devez être inscrit et connecté pour voir ce lien] 55-7170 [Vous devez être inscrit et connecté pour voir ce lien]; MTOW: 7,200 lb (3,300 kg).


Model 18B

Improved model with increased range and useful load, fitted with 285 hp (213 kW) [Vous devez être inscrit et connecté pour voir ce lien] engines.

• Model S18B
  

Version of Model 18B capable of being fitted with skis or floats.


Model 18D

Variant with seating for two pilots and nine passengers, fitted with [Vous devez être inscrit et connecté pour voir ce lien] engines of 330 horsepower (250 kW). MTOW: 7,200 lb (3,300 kg).

• Model S18D
  

Version of Model 18D capable of being fitted with skis or Edo 55-7170 floats; MTOW: 7,170 lb (3,250 kg).


Model A18D

Variant of 18D with MTOW increased by 300 lb (140 kg) to 7,500 lb (3,400 kg), fitted with Jacobs L-6 engines.

• Model SA18D
  

Seaplane version of Model A18D but same MTOW as S18D, fitted with Edo 55-7170 floats.


Model A18A

Version fitted with Wright R-760 engines of 350 horsepower (260 kW). MTOW: 7,500 lb (3,400 kg).

• Model SA18A
  

Seaplane version of Model A18A, fitted with Edo 55-7170 floats; MTOW: 7,170 lb (3,250 kg).^{[Vous devez être inscrit et connecté pour voir ce lien]}


Model 18R

Model with [Vous devez être inscrit et connecté pour voir ce lien] engines of 420 horsepower (310 kW); seven built, one to Sweden as an [Vous devez être inscrit et connecté pour voir ce lien], six to Nationalist China as M18R light bombers.


Model 18S

Nine-passenger pre-World War II civil variant, served as basis for USAAF C-45C.


Model B18S

Nine-passenger pre-World War II civil variant, served as basis for USAAF F-2.


Model C18S

Variant of B18S with seating for eight passengers, and equipment and minor structural changes.


Model D18S

First post-World War II variant introduced in 1945 with seating for eight passengers and MTOW of 8,750 lb (3,970 kg). 1,035 built (c/nos. A-1 to A-1035).

• 3N: Version of D18S delivered to the [Vous devez être inscrit et connecté pour voir ce lien] (RCAF); 100 built (c/nos. A-601
  to A-700, re-serialled as CA-1 to CA-100).^{[Vous devez être inscrit et connecté pour voir ce lien]}
  
• 3NM: Version of D18S delivered to the RCAF;
  133 built (c/nos. A-702 to A-715, A-736 to A-755, A-767 to A-769, A-780,
  A-782, A-784, A-786, A-788, A-790 to A-800, A-851 to A-930; re-serialled
  as CA-102 to CA-115, CA-136 to CA-155, CA-176 to CA-194, CA-201 to CA-280).
  
• 3TM: Version of D18S delivered to the RCAF;
  48 built (c/nos. A-701, A-716 to A-735, A-756 to A-766, A-770 to A-779, A-781, A-783, A-785, A-787, A-789 and A-931; re-serialled as CA-101, CA-116 to CA-135, CA-156 to CA-175, CA-195 to CA-200 and CA-281).
  

Model D18C

Variant with [Vous devez être inscrit et connecté pour voir ce lien] engines of 525 horsepower (391 kW) and MTOW of 9,000 lb (4,100 kg), introduced in 1947. 31 built (c/nos. AA-1 to AA-31).


Model E18S

Variant with redesigned wing and MTOW of 9,300 lb (4,200 kg); 403 built (c/nos. BA-1 to BA-402 and BA-497).


Model E18S-9700

Variant of E18S with MTOW of 9,700 lb (4,400 kg); 57 built (c/nos. BA-403 to BA-433, BA-435 to BA-460).


Model G18S

Superseded E18S, MTOW of 9,700 lb (4,400 kg); 155 built (c/nos. BA-434, BA-461 to BA-496, BA-498 to BA-562,
BA-564 to BA-579, BA-581 to BA-617).

Model G18S-9150

Lightweight version of G18, MTOW of 9,150 lb (4,150 kg); 1 built (c/no. BA-563).

Model H18

Last production version, fitted with optional tricycle undercarriage developed by Volpar and MTOW of 9,900 lb
(4,500 kg); 149 built (c/nos. BA-580, BA-618 to BA-765), of which 109 were manufactured with tricycle undercarriage.^{[Vous devez être inscrit et connecté pour voir ce lien]}

Military versions



C-45

Six seat staff transport based on C18S. 11 built.


C-45A

Eight seat utility transport based on C18S. 20 built.


RC-45A

Redesignation of all surviving F-2, F-2A and F-2B aircraft by the [Vous devez être inscrit et connecté pour voir ce lien] in 1948.


C-45B

Based on C18S but with modified internal layout, 223 ordered. Re-designated UC-45B in 1943.

• Expeditor I: Some C-45Bs were supplied to the [Vous devez être inscrit et connecté pour voir ce lien] under [Vous devez être inscrit et connecté pour voir ce lien].
  

C-45C

Two Model 18S aircraft impressed into the USAAF. Re-designated UC-45C in January 1943.

C-45D

Designation given to two AT-7 aircraft converted as passenger transports during manufacture (USAAF s/nos. 42-56785 and 43-33281). Re-designated UC-45D in January 1943.

C-45E

Designation given to two AT-7 and four AT-7B aircraft converted as passenger transports during manufacture (USAAF s/nos. 42-43484, 42-43486, 43-33282 to 43-33285). Re-designated UC-45E in January 1943.

C-45F

Standardised seven-seat version based on C18S, with longer nose than preceding models; 1,137 ordered. Redesignated UC-45F.

• Expeditor II: C-45Fs supplied to the RAF and [Vous devez être inscrit et connecté pour voir ce lien] under Lend-Lease.
  
• Expeditor III: C-45Fs supplied to the [Vous devez être inscrit et connecté pour voir ce lien] under Lend-Lease.
  

C-45G

AT-7s and AT-11s remanufactured in early 1950s for the [Vous devez être inscrit et connecté pour voir ce lien] (USAF) to similar standard as civil D18S with [Vous devez être inscrit et connecté pour voir ce lien] and R-985-AN-3 engines. 372 aircraft rebuilt (c/nos. AF-61 to AF-60, AF-157 to AF-468; USAF s/nos. 51-11444 to 51-11503, 51-11600 to 51-11911).

TC-45G

Multi-engine crew trainer variant of C-45G; AT-7s and AT-11s remanufactured in early 1950s for the USAF to similar
standard as civil D18S. 96 aircraft rebuilt (c/nos. AF-61 to AF-156, USAF s/nos. 51-11504 to 51-11599).


C-45H

AT-7s and AT-11s remanufactured in early 1950s for the USAF to similar standard as civil D18S, with no autopilot
and R-985-AN-14B engines. 432 aircraft rebuilt (c/nos. AF-469 to AF-900; USAF s/nos. 52-10539 to 52-10970).


TC-45H


RC-45J

In 1962 all surviving US Navy SNB-5Ps were redesignated RC-45J.

TC-45J

In 1962 all surviving US Navy SNB-5s were redesignated TC-45J.

UC-45J

AT-7 Navigator

Navigation trainer based on C18S, with an [Vous devez être inscrit et connecté pour voir ce lien] and positions for three students.
Powered by 450 hp (336 kW) R-985-25 engines. 577 built.

AT-7A

Floatplane version of AT-7. Six built.

AT-7B

Winterised AT-7. Nine built.

AT-7C

Based on C18S with R-985-AN3 engines. 549 built.


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; fitted with two machine guns, one in nose and one in a dorsal gun turret. 1,582 built for USAAF orders, with 24 ordered by Netherlands repossessed by USAAF and used by the Royal Netherlands Military Flying School at [Vous devez être inscrit et connecté pour voir ce lien].

AT-11A

Conversion of AT-11 as navigation trainer. 36 converted.

CQ-3

Conversion of UC-45F, modified to act as [Vous devez être inscrit et connecté pour voir ce lien] control aircraft. Re-designated as DC-45F in June 1948.

F-2

Photo-reconnaissance version based on B18.

F-2A

Improved version.

F-2B

JRB-1

Photographic aircraft for the US Navy, based on the C18S, fitted with fairing over cockpit for improved visibility. 11 built.

JRB-2

Light transport for the US Navy, based on the C18S. 15 built.

JRB-3

Photographic version, similar to C-45B, 23 built.

JRB-4

Utility transport version, equivalent to UC-45F, 328 built.

JRB-6

SNB-1

Variant for the US Navy, similar to AT-11. 110 built.

SNB-2

Navigation trainer for the US Navy. Similar to AT-7. 299 built.

SNB-2C

Variant for the US Navy, similar to AT-7C.


SNB-2H

Ambulance conversion for the US Navy.

SNB-2P

Photo reconnaissance trainer for the US Navy.

SNB-3

Variant for the US Navy, similar to AT-7C.

SNB-3Q

Electronic counter-measures trainer for the US Navy.

SNB-5

SNB-2s and SNB-2Cs were remanufactured, and designated SNB-5 by the US Navy.

SNB-5P

Photographic-reconnaissance trainer for the US Navy.

Un AT-11 ( Beech 18 )

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